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Structural and Biochemical Studies Enlighten the Unspecific Peroxygenase from Hypoxylon sp. EC38 as an Efficient Oxidative Biocatalyst
Unspecific peroxygenases (UPOs) are glycosylated fungal enzymes that can selectively oxidize C-H bonds. UPOs employ hydrogen peroxide as the oxygen donor and reductant. With such an easy-to-handle cosubstrate and without the need for a reducing agent, UPOs are emerging as convenient oxidative biocatalysts. Here, an unspecific peroxygenase from Hypoxylon sp. EC38 (HspUPO) was identified in an activity-based screen of six putative peroxygenase enzymes that were heterologously expressed in Pichia pastoris. The enzyme was found to tolerate selected organic solvents such as acetonitrile and acetone. HspUPO is a versatile catalyst performing various reactions, such as the oxidation of prim- and sec-alcohols, epoxidations, and hydroxylations. Semipreparative biotransformations were demonstrated for the nonenantioselective oxidation of racemic 1-phenylethanol rac-1b (TON = 13 000), giving the product with 88% isolated yield, and the oxidation of indole 6a to give indigo 6b (TON = 2800) with 98% isolated yield. HspUPO features a compact and rigid three-dimensional conformation that wraps around the heme and defines a funnel-shaped tunnel that leads to the heme iron from the protein surface. The tunnel extends along a distance of about 12 ? with a fairly constant diameter in its innermost segment. Its surface comprises both hydrophobic and hydrophilic groups for dealing with substrates of variable polarities. The structural investigation of several protein-ligand complexes revealed that the active site of HspUPO is accessible to molecules of varying bulkiness with minimal or no conformational changes, explaining the relatively broad substrate scope of the enzyme. With its convenient expression system, robust operational properties, relatively small size, well-defined structural features, and diverse reaction scope, HspUPO is an exploitable candidate for peroxygenase-based biocatalysis.
Ebner, Katharina,Glieder, Anton,Kroutil, Wolfgang,Mattevi, Andrea,Rinnofner, Claudia,Rotilio, Laura,Swoboda, Alexander
p. 11511 - 11525
(2021/09/22)

CROSS-LINKING COMPOUNDS AND METHODS OF USE THEREOF
Compounds comprising a cross-linking moiety and a protecting group are described herein along with their methods of use. The cross-linking moiety may comprise an indoxyl and the protecting group may comprise a sugar (e.g., a glucuronide or glucoside), phosphoester, or sulfoester group. The cross-linking moiety and protecting group may be attached to each other via an oxygen atom, sulfur atom, or linker. In some embodiments, the linker attaching the cross-linking moiety and protecting group is a self-immolative linker. A compound of the present invention may cross-link under physiological conditions and/or in vivo.
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(2021/01/29)

CROSS-LINKING COMPOUNDS AND METHODS OF USE THEREOF
Compounds of Formula IA, IB, II, III, IV, and/or V are described herein along with their methods of use. A compound of the present invention may cross-link under physiological conditions and/or in vivo.
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(2021/05/15)

Indigo Formation and Rapid NADPH Consumption Provide Robust Prediction of Raspberry Ketone Synthesis by Engineered Cytochrome P450 BM3
Natural raspberry ketone has a high value in the flavor, fragrance and pharmaceutical industries. Its extraction is costly, justifying the search for biosynthetic routes. We hypothesized that cytochrome P450 BM3 (P450 BM3) could be engineered to catalyze the hydroxylation of 4-phenyl-2-butanone, a naturally sourceable precursor, to raspberry ketone. The synthesis of indigo by variants of P450 BM3 has previously served as a predictor of promiscuous oxidation reactions. To this end, we screened 53 active-site variants of P450 BM3 using orthogonal high-throughput workflows to identify the most streamlined route to all indigo-forming variants. Among the three known and 13 new indigo-forming variants, eight hydroxylated 4-phenyl-2-butanone to raspberry ketone. Previously unreported variant A82Q displayed the highest initial rates and coupling efficiencies in synthesis of indigo and of raspberry ketone. It produced the highest total concentration of raspberry ketone despite producing less total indigo than previously reported variants. Its productivity, although modest, clearly demonstrates the potential for development of a biocatalytic route to raspberry ketone. In addition to validating indigo as a robust predictor of this promiscuous activity, we demonstrate that monitoring rapid NADPH consumption serves as an alternative predictor of a promiscuous reactivity in P450 BM3.
Rousseau, Olivier,Ebert, Maximilian C. C. J. C.,Quaglia, Daniela,Fendri, Ali,Parisien, Adem H.,Besna, Jonathan N.,Iyathurai, Saathanan,Pelletier, Joelle N.
p. 837 - 845
(2019/12/15)

Enzymatic synthesis of indigo-derivative industrial dyes
Synthetic indigo is among the most important industrial dyes. Unfortunately, synthetic indigo has raised environmental concern due to the use of pollutant and hazardous chemicals. In response, green chemistry aims to find new environmentally friendly and economically attractive synthesis methods. Accordingly, this work describes the enzymatic synthesis of indigo and its derivatives starting from indole. A variant of the heme domain of cytochrome P450 from Bacillus megaterium, CYPBM3F87A, was used to catalyze the synthesis of indigo and three di-substituted derivatives. Substrates transformed by a peroxygenase reaction were indole, 4-bromoindole, 5-methoxyindole and 7-methoxyindole. The kinetic data fitted to Hill's mathematical model with kcat values of 3.51, 0.94, 4.72, and 4.28 min?1 for each substrate, respectively. In all cases, colored products were obtained that were characterized by spectrometric techniques. Furthermore, the CYPBM3F87A enzyme was immobilized on magnetic nanoparticles that exhibited catalytic rate in the synthesis of indigo from indole (kcat 0.72 min?1). Our results show that enzymatic synthesis of industrial dyes without the use of expensive cofactors offers an attractive and plausible alternative to conventional chemical synthesis with a lower environment impact.
Chauhan, Kanchan,Mendoza-Avila, Josemarco,Vazquez-Duhalt, Rafael
(2020/03/31)

Exploring an anomaly: The synthesis of 7,7′-diazaindirubin through a 7-azaindoxyl intermediate
Two independent methods generating 7-azaindoxyl as an intermediate verify that 7,7′-diazaindirubin is formed exclusively over 7,7′-diazaindigo. This contrasts with long-standing knowledge related to the reactivity of indoxyl, which proceeds via a radical-initiated homodimerization process, leading to indigo. A series of experiments confirms 7-azaindoxyl as an intermediate with results suggesting a condensation pathway followed by oxidation.
DeYoung, James R.,Lipsius, Richard J.,Patterson, Andrew C.,Shriver, James A.,Wang, Katelyn R.
p. 36849 - 36852
(2020/10/26)

AMMONIA DETECTION MATERIAL AND DETECTOR
An ammonia detection material and a detector including the ammonia detection material are provided. The ammonia detection material is capable of detecting ammonia easily, sensitively, continuously and selectively. The ammonia detection material of the present invention is represented by general formula (1): M1xFey(Pyrazine)s[Ni1-tM2t(CN)4]. zH2O, wherein M1=Co, Cu; 0.6≤x≤1.05; 0≤y≤0.4; 0≤s≤1; M2=Pd, Pt; 0≤t0.15; 0≤z≤6.
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(2020/11/24)

Enzymatically triggered chromogenic cross-linking agents under physiological conditions
The ability to cross-link molecules upon enzymatic action under physiological conditions holds considerable promise for use in diverse life sciences applications. Here, an enzymatically triggered "click reaction" has been developed by exploiting the longstanding indigo-forming reaction from indoxyl β-glucoside. The covalent cross-linking proceeds in aqueous solution, requires the presence only of an oxidant (e.g., O2), and is readily detectable owing to the blue color of the resulting indigoid dye. To achieve facile indigoid formation in the presence of a bioconjugatable tether, diverse indoxyl β-glucosides were synthesized and studied in enzyme assays with four glucosidases including from tritosomes (derived from hepatic lysosomes) and rat liver homogenates. Altogether 36 new compounds (including 15 target indoxyl-glucosides for enzymatic studies) were prepared and fully characterized in pursuit of four essential requirements: enzyme triggering, facile subsequent indigoid dye formation, bioconjugatability, and synthetic accessibility. The 4,6-dibromo motif in a 5-alkoxy-substituted indoxyl-glucoside was a key design feature for fast and high-yielding indigoid dye formation. Two attractive molecular designs include (1) an indoxyl-glucoside linked to a bicyclo[6.1.0]nonyl (BCN) group for Cu-free click chemistry, and (2) a bis(indoxyl-glucoside). In both cases the linker between the reactive moieties is composed of two short PEG groups and a central triazine derivatized with a sulfobetaine moiety for water solubilization. Glucosidase treatment of the bis(indoxyl-glucoside) in aqueous solution gave oligomers that were characterized by absorption, dynamic light-scattering, and 1H NMR spectroscopy; optical microscopy; mass spectrometry; and HPLC. Key attractions of in situ indigoid dye formation, beyond enzymatic triggering under physiological conditions without exogenous catalysts or reagents, are the chromogenic readout and compatibility with attachment to diverse molecules.
Fujita, Hikaru,Dou, Jinghuai,Matsumoto, Nobuyuki,Wu, Zhiyuan,Lindsey, Jonathan S.
p. 719 - 743
(2020/01/31)

Indigoid dyes by group e monooxygenases: Mechanism and biocatalysis
Since ancient times, people have been attracted by dyes and they were a symbol of power. Some of the oldest dyes are indigo and its derivative Tyrian purple, which were extracted from plants and snails, respectively. These 'indigoid dyes' were and still are used for coloration of textiles and as a food additive. Traditional Chinese medicine also knows indigoid dyes as pharmacologically active compounds and several studies support their effects. Further, they are interesting for future technologies like organic electronics. In these cases, especially the indigo derivatives are of interest but unfortunately hardly accessible by chemical synthesis. In recent decades, more and more enzymes have been discovered that are able to produce these indigoid dyes and therefore have gained attention from the scientific community. In this study, group E monooxygenases (styrene monooxygenase and indole monooxygenase) were used for the selective oxygenation of indole (derivatives). It was possible for the first time to show that the product of the enzymatic reaction is an epoxide. Further, we synthesized and extracted indigoid dyes and could show that there is only minor by-product formation (e.g. indirubin or isoindigo). Thus, group E monooxygenase can be an alternative biocatalyst for the biosynthesis of indigoid dyes.
Heine, Thomas,Gro?mann, Carolin,Hofmann, Sarah,Tischler, Dirk
p. 939 - 950
(2019/03/19)

High-Performance Ambipolar Polymers Based on Electron-Withdrawing Group Substituted Bay-Annulated Indigo
For donor–acceptor conjugated polymers, it is an effective strategy to improve their electron mobilities by introducing electron-withdrawing groups (EWGs, such as F, Cl, or CF3) into the polymer backbone. However, the introduction of different EWGs always requires a different synthetic approach, leading to additional arduous work. Here, an effective two-step method is developed to obtain EWG substituted bay-annulated indigo (BAI) units. This method is effective to introduce various EWGs (F, Cl, or CF3) into BAI at different substituted positions. Based on this method, EWG substituted BAI acceptors, including 2FBAI, 2ClBAI, and 2CF3BAI, are reported for the first time. Furthermore, four polymers of PBAI-V, P2FBAI-V, P2ClBAI-V, and P4OBAI-V are developed. All the polymers show ambipolar transport properties. Particularly, P2ClBAI-V exhibits remarkable hole and electron mobilities of 4.04 and 1.46 cm2 V?1 s?1, respectively. These mobilities are among the highest values for BAI-based polymers.
Yang, Jie,Jiang, Yaqian,Tu, Zeyi,Zhao, Zhiyuan,Chen, Jinyang,Yi, Zhengran,Li, Yifan,Wang, Shuai,Yi, Yuanping,Guo, Yunlong,Liu, Yunqi
(2019/01/05)

Green and efficient biosynthesis of indigo from indole by engineered myoglobins
With the demand nowadays for blue dyes, it is of practical importance to develop a green and efficient biocatalyst for the production of indigo. The design of artificial enzymes has been shown to be attractive in recent years. In a previous study, we engineered a single mutant of sperm whale myoglobin, F43Y Mb, with a novel Tyr-heme cross-link. In this study, we found that it can efficiently catalyze the oxidation of indole to indigo, with a yield as high as 54% compared to the highest yield (～20%) reported to date in the literature. By further modifying the heme active site, we engineered a double mutant of F43Y/H64D Mb, which exhibited the highest catalytic efficiency (198 M?1 s?1) among the artificial enzymes designed in Mb. Moreover, both F43Y Mb and F43Y/H64D Mb were found to produce the indigo product with a chemoselectivity as high as ～80%. Based on the reaction system, we also established a convenient and green dyeing method by dyeing a cotton textile during the biosynthesis of indigo, followed by further spraying the concentrated indigo, without the need of strong acids/bases or any reducing agents. The successful application of dyeing a white cotton textile with a blue color further indicates that the designed enzyme and the dyeing method have practical applications in the future.
Liu, Can,Xu, Jiakun,Gao, Shu-Qin,He, Bo,Wei, Chuan-Wan,Wang, Xiao-Juan,Wang, Zhonghua,Lin, Ying-Wu
p. 33325 - 33330
(2018/10/20)

Bromo-substituted cibalackrot backbone, a versatile donor or acceptor main core for organic optoelectronic devices
Cibalackrot (Ci-I), one of the latest highly conjugated compound possessing bis-lactam structure, was investigated with respect to their brominated derivatives in order to determine their suitable substitution points for the syntheses of new class of small molecules for optoelectronic devices. 7,14-Bis(4-bromophenyl) (Ci-II) and 3,10-dibromo (Ci-III) derivatives of cibalackrot possess moderately narrow band gaps of 2.15 and 2.09 eV, respectively. Notably, Ci-III dye exhibits more red-shifted ultraviolet–visible (UV–vis) absorption and fluorescence emission spectra as compared to that of Ci-II dye because Ci-III shows more prominent intramolecular charge transfer (ICT) complex than that of Ci-II dye. Electron mobilities of the order of 7.0 × 10?4 cm2/V and 3.1 × 10?4 cm2/V were measured using Ci-II and Ci-III as active layer, respectively. Charge transfer properties of the molecules were investigated in bulk heterojunction device configuration wherein Ci-III showed p-type behavior against n-type PCBM in photovoltaic device. Photovoltaic performance of Ci-III dye which was used as donor component is 20 times higher than that of the device in which this dye was used as acceptor.
Din?alp, Haluk,Saltan, G?zde Murat,Zafer, Ceylan,K?ymaz, Deniz Aykut
p. 512 - 520
(2018/09/14)

Generation and Reactivity of Electron-Rich Carbenes on the Surface of Catalytic Gold Nanoparticles
The reactive nature of carbenes can be modulated, and ultimately reversed, by receiving additional electron density from a metal. Here, it is shown that Au nanoparticles (NPs) generate an electron-rich carbene on surface after transferring electron density to the carbonyl group of an in situ activated diazoacetate, as assessed by Fourier transformed infrared (FT-IR) spectroscopy, magic angle spinning nuclear magnetic resonance (MAS NMR), and Raman spectroscopy. Density functional theory (DFT) calculations support the observed experimental values and unveil the participation of at least three different Au atoms during carbene stabilization. The surface stabilized carbene shows an extraordinary stability against nucleophiles and reacts with electrophiles to give new products. These findings showcase the ability of catalytic Au NPs to inject electron density in energetically high but symmetrically allowed valence orbitals of sluggish molecules.
Oliver-Meseguer, Judit,Boronat, Mercedes,Vidal-Moya, Alejandro,Concepción, Patricia,Rivero-Crespo, Miguel ángel,Leyva-Pérez, Antonio,Corma, Avelino
supporting information
p. 3215 - 3218
(2018/03/13)

AN IMPROVED PROCESS FOR THE PREPARATION OF INDIGO CARMINE
The present invention relates to an improved process for preparation of Indigo carmine of Formula (I), in high purity more than 99.5%.
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(2017/06/27)

Biosynthesis of indigo in Escherichia coli expressing self-sufficient CYP102A from Streptomyces cattleya
Cytochrome P450 monooxygenases (CYP) are a superfamily of heme-thiolate proteins which catalyze the incorporation of oxygen atoms into substrates. Here, a self-sufficient CYP102A from Streptomyces cattleya (CYP102A_scat) was cloned, produced recombinantly in Escherichia coli strain BL21 (DE3), and the characteristic features were investigated. However, unlike other self-sufficient CYP102A enzymes that have been reported, CYP102A_scat was found to be able to catalyze intracellular hydroxylation of indole molecules with 3-C specific regioselectivity. Consequently, E.?coli strains producing CYP102A_scat could synthesize approximately 1.0?g/L of indigo in LB media. Optimization of indigo synthesis was investigated through additional feeding of indole precursors such as glucose, L-tryptophan, and indole. Indigo production reached up to 3.8?±?0.1?g/L by adding 20?μM of extracellular indole and 0.2?mM of L-tryptophan to the LB media. To our knowledge, this is a record and the highest yield achieved so far.
Kim, Hee-Jung,Jang, Seyoung,Kim, Joonwon,Yang, Yung-Hun,Kim, Yun-Gon,Kim, Byung-Gee,Choi, Kwon-Young
p. 29 - 35
(2017/01/28)

Paper-based acetylcholinesterase inhibition assay combining a wet system for organophosphate and carbamate pesticides detection
A dramatic increase in pesticide usage in agriculture highlights the need for on-site monitoring for public health and safety. Here, a paper-based sensor combined with a wet system was developed for the simple and rapid screening of organophosphate (OP) and carbamate (CM) pesticides based on the inhibition of acetylcholinesterase (AChE). The paper-based sensor was designed as a foldable device consisting of a cover and detection sheets pre-prepared with indoxyl acetate and AChE, respectively. The paper-based sensor requires only the incubation of a sample on the test zone for 10 minutes, followed by closing of the foldable sheet to initiate the enzymatic reaction. Importantly, the buffer loading hole was additionally designed on the cover sheet to facilitate the interaction of the coated substrate and the immobilized enzyme. This subsequently facilitates the mixing of indoxyl acetate with AChE, resulting in the improved analytical performance of the sensor. The absence or decrease in blue color produced by the AChE hydrolysis of indoxyl acetate can be observed in the presence of OPs and CMs. Under optimized conditions and using image analysis, the limit of detection (LOD) of carbofuran, dichlorvos, carbaryl, paraoxon, and pirimicarb are 0.003, 0.3, 0.5, 0.6, and 0.6 ppm, respectively. The assay could be applied to determine OP and CM residues in spiked food samples. Visual interpretation of the color signal was clearly observed at the concentration of 5 mg/kg. Furthermore, a self-contained sample pre-concentration approach greatly enhanced the detection sensitivity. The paper-based device developed here is low-cost, requires minimal reagents and is easy to handle. As such, it would be practically useful for pesticide screening by nonprofessional end-users.
Apilux, Amara,Ayudhya, Chartchalerm Isarankura-Na,Tantimongcolwat, Tanawut,Prachayasittikul, Virapong
p. 307 - 319
(2015/03/14)

Determination of acetylcholinesterase and butyrylcholinesterase activity without dilution of biological samples
Two cholinesterases: acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), are known. The enzymes are important in the body and alteration of their activity has significant use in the diagnosis of poisoning, liver function, etc. Currently available methods for the determination of cholinesterases have some major drawbacks including various interferences and the inability to be used for decreasing the enzyme activity in the presence of reversible inhibitors due to sample dilution; hence, a method for dilution free assay of cholinesterases is desired. Here, microplates were modified with indoxylacetate (100 μL of 10 mmol L-1 solution) and used for cholinesterases assay after drying at 37 °C. The fact that indoxylacetate remains stable in dry state and serves simultaneously as a chromogen and substrate provide good prerequisites for the method. The limit of detection for BChE was 0.71 U while that for AChE was 2.8 U per a 100 μL sample (solution of enzyme or plasma sample). The limit of detection is low enough to allow standard examination of cholinesterasemia. The two cholinesterases can be distinguished from each other using selective inhibitors such as donepezil and iso-OMPA. The new method was also successfully validated for the standard Ellman's assay using plasma samples with BChE activity adjusted by carbofuran. The new method based on indoxylacetate seems promising for routine tests.
Pohanka, Miroslav
p. 1044 - 1049
(2015/06/08)

Versatile de novo enzyme activity in capsid proteins from an engineered M13 bacteriophage library
Biocatalysis has grown rapidly in recent decades as a solution to the evolving demands of industrial chemical processes. Mounting environmental pressures and shifting supply chains underscore the need for novel chemical activities, while rapid biotechnological progress has greatly increased the utility of enzymatic methods. Enzymes, though capable of high catalytic efficiency and remarkable reaction selectivity, still suffer from relative instability, high costs of scaling, and functional inflexibility. Herein, we developed a biochemical platform for engineering de novo semisynthetic enzymes, functionally modular and widely stable, based on the M13 bacteriophage. The hydrolytic bacteriophage described in this paper catalyzes a range of carboxylic esters, is active from 25 to 80 °C, and demonstrates greater efficiency in DMSO than in water. The platform complements biocatalysts with characteristics of heterogeneous catalysis, yielding high-surface area, thermostable biochemical structures readily adaptable to reactions in myriad solvents. As the viral structure ensures semisynthetic enzymes remain linked to the genetic sequences responsible for catalysis, future work will tailor the biocatalysts to high-demand synthetic processes by evolving new activities, utilizing high-throughput screening technology and harnessing M13's multifunctionality.
Casey, John P.,Barbero, Roberto J.,Heldman, Nimrod,Belcher, Angela M.
supporting information
p. 16508 - 16514
(2015/02/02)

Pullulan encapsulation of labile biomolecules to give stable bioassay tablets
A simple and inexpensive method is reported for the long-term stabilization of enzymes and other unstable reagents in premeasured quantities in water-soluble tablets (cast, not compressed) made with pullulan, a nonionic polysaccharide that forms an oxygen impermeable solid upon drying. The pullulan tablets dissolve in aqueous solutions in seconds, thereby facilitating the easy execution of bioassays at remote sites with no need for special reagent handling and liquid pipetting. This approach is modular in nature, thus allowing the creation of individual tablets for enzymes and their substrates. Proof-of-principle demonstrations include a Taq polymerase tablet for DNA amplification through PCR and a pesticide assay kit consisting of separate tablets for acetylcholinesterase and its chromogenic substrate, indoxyl acetate, both of which are highly unstable. The encapsulated reagents remain stable at room temperature for months, thus enabling the room-temperature shipping and storage of bioassay components.
Jahanshahi-Anbuhi, Sana,Pennings, Kevin,Leung, Vincent,Liu, Meng,Carrasquilla, Carmen,Kannan, Balamurali,Li, Yingfu,Pelton, Robert,Brennan, John D.,Filipe, Carlos D. M.
p. 6155 - 6158
(2014/06/23)

Indigo dye production by enzymatic mimicking based on an iron(III)porphyrin
A novel indigo synthesis is based on a simple and cost-effective model system of the enzymes involved in the natural and biocatalytic productions. The method considers the oxidation of indole by hydrogen peroxide, being catalyzed by an iron(III)porphyrin in ethanol, as solvent, and no other additives. The yields of indigo and of the other oxidized indolinoid derivatives were found to be dependent on the metalloporphyrin system used and on the control of the oxidation conditions. Significant reductions of the environmental impact relatively to the present industrial production and of the costs relatively to the biocatalytic methodologies were obtained. The enhanced indigo production in the presence of the iron(III)porphyrin-ethanol catalytic system relatively to the manganese(III)porphyrin-acetonitrile system can be rationalized by the formation of different active species in the two systems.
Rebelo, Susana L.H.,Linhares, Margarida,Simoes, Mario M.Q.,Silva, Artur M.S.,Neves, M. Graca P.M.S.,Cavaleiro, Jose A.S.,Freire, Cristina
p. 33 - 40
(2014/06/09)

Peroxygenase and oxidase activities of dehaloperoxidase-hemoglobin from Amphitrite ornata
The marine globin dehaloperoxidase-hemoglobin (DHP) from Amphitrite ornata was found to catalyze the H2O2-dependent oxidation of monohaloindoles, a previously unknown class of substrate for DHP. Using 5-Br-indole as a representative substrate, the major monooxygenated products were found to be 5-Br-2-oxindole and 5-Br-3-oxindolenine. Isotope labeling studies confirmed that the oxygen atom incorporated was derived exclusively from H2O2, indicative of a previously unreported peroxygenase activity for DHP. Peroxygenase activity could be initiated from either the ferric or oxyferrous states with equivalent substrate conversion and product distribution. It was found that 5-Br-3-oxindole, a precursor of the product 5-Br-3-oxindolenine, readily reduced the ferric enzyme to the oxyferrous state, demonstrating an unusual product-driven reduction of the enzyme. As such, DHP returns to the globin-active oxyferrous form after peroxygenase activity ceases. Reactivity with 5-Br-3-oxindole in the absence of H2O2 also yielded 5,5′-Br2-indigo above the expected reaction stoichiometry under aerobic conditions, and O2-concentration studies demonstrated dioxygen consumption. Nonenzymatic and anaerobic controls both confirmed the requirements for DHP and molecular oxygen in the catalytic generation of 5,5′-Br2-indigo, and together suggest a newly identified oxidase activity for DHP.
Barrios, David A.,D'Antonio, Jennifer,McCombs, Nikolette L.,Zhao, Jing,Franzen, Stefan,Schmidt, Andreas C.,Sombers, Leslie A.,Ghiladi, Reza A.
supporting information
p. 7914 - 7925
(2014/06/23)

Development of a practical one-pot synthesis of indigo from indole
A novel and highly practical one-pot synthesis of indigo from indole via 3-position selective oxidation and dimerization of the indole framework was developed. Using 0.1 mol% of molybdenum complex and 2.2 equivalents of cumene hydroperoxide in tert-butyl alcohol, the reaction was complete in 7 h and pure indigo was obtained in 81% yield as a deep-blue solid just by filtration. The described one-step method renders the pure indigo readily available on a large scale using only inexpensive raw materials.
Yamamoto, Yoshihiro,Inoue, Yoshihisa,Takaki, Usaji,Suzuki, Hiroharu
experimental part
p. 82 - 89
(2011/04/12)

Exploring the biocatalytic scope of a bacterial flavin-containing monooxygenase
A bacterial flavin-containing monooxygenase (FMO), fused to phosphite dehydrogenase, has been used to explore its biocatalytic potential. The bifunctional biocatalyst could be expressed in high amounts in Escherichia coli and was able to oxidize indole and indole derivatives into a variety of indigo compounds. The monooxygenase also performs the sulfoxidation of a wide range of prochiral sulfides, showing moderate to good enantioselectivities in forming chiral sulfoxides. The Royal Society of Chemistry 2011.
Rioz-Martinez, Ana,Kopacz, Malgorzata,De Gonzalo, Gonzalo,Torres Pazmino, Daniel E.,Gotor, Vicente,Fraaije, Marco W.
experimental part
p. 1337 - 1341
(2011/04/23)

Guanine-rich RNAs and DNAs that bind heme robustly catalyze oxygen transfer reactions
Diverse guanine-rich RNAs and DNAs that fold to form guanine quadruplexes are known to form tight complexes with Fe(III) heme. We show here that a wide variety of such complexes robustly catalyze two-electron oxidations, transferring oxygen from hydrogen peroxide to thioanisole, indole, and styrene substrates. Use of 18O-labeled hydrogen peroxide reveals the source of the oxygen transferred to form thioanisole sulfoxide and styrene oxide to be the activated ferryl moiety within these systems. Hammett analysis of the kinetics of thioanisole sulfoxide formation is unable to distinguish between a one-step, direct oxygen transfer and a two-step, oxygen rebound mechanism for this catalysis. Oxygen transfer to indole produces a range of products, including indigo and related dyes. Docking of heme onto a high-resolution structure of the G-quadruplex fold of Bcl-2 promoter DNA, which both binds heme and transfers oxygen, suggests a relatively open active site for this class of ribozymes and deoxyribozymes. That heme-dependent catalysis of oxygen transfer is a property of many RNAs and DNAs has ramifications for primordial evolution, enzyme design, cellular oxidative disease, and anticancer therapeutics.
Poon, Lester C.-H.,Methot, Stephen P.,Morabi-Pazooki, William,Pio, Frederic,Bennet, Andrew J.,Sen, Dipankar
supporting information; experimental part
p. 1877 - 1884
(2011/04/22)

Altering the regioselectivity of cytochrome P450 BM-3 by saturation mutagenesis for the biosynthesis of indirubin
Engineering the regioselectivity of enzymes to fulfill application needs is an important goal of protein engineering. To create biocatalysts suitable for the biosynthesis of indirubin (a drug for chronic myelogenous leukemia and a novel promising anticancer agent), cytochrome P450 BM-3 was engineered by site-directed saturation mutagenesis at position D168 to alter its hydroxylation regioselectivity towards indole. One mutant, D168W, was created. It primarily produces indirubin (～90%) whereas the parent enzyme primarily forms indigo (～85%). Docking calculations showed that the mutation altered the orientation of indole, and that the C-2 of the indole pyrrole ring was closer to the heme iron of P450 BM-3 than the C-3. The mutation possibly shifted the hydroxylation preference of P450 BM-3 for indole from the C-3 to C-2, which may be responsible for the reversal of distribution of the product yield. This mutant yielded high-purity indirubin and may be a good starting point for the biosynthesis of indirubin.
Hu, Sheng,Huang, Jun,Mei, Lehe,Yu, Qing,Yao, Shanjing,Jin, Zhihua
experimental part
p. 29 - 35
(2010/12/20)

Tuning the substrate specificity by engineering the active site of cytochrome P450cam: A rational approach
Rational design of the active site of cytochrome P450cam has been carried out to catalyse oxygenation of various potentially important chemical reactions. The modeling studies showed that the distal pocket of the heme consisting of the Y96, T101, F87 and L244 residues could be suitably mutated to change the substrate specificity of the enzyme. We found that the mutant enzymes could catalyse oxygenation of indole to produce indigo. While Y96F was found to be several times better as a catalyst for conversion of indole to indigo, the double mutant Y96F/L244A showed the highest NADH oxidation rate as well as yield of indigo. The oxidative catalysis using H2O2 as the oxygen source was found to produce a higher purity of indigo, and lesser or no formation of indirubin was detected. The enzymatic oxygenation of aromatic hydrocarbons such as coumarin and analogues was also found to be enhanced on mutation of Y96 and L244 residues in the enzyme. The studies also showed that mutation of suitable residues can alter the regio-selectivity of hydroxylation of the aromatic hydrocarbons.
Manna, Soumen Kanti,Mazumdar, Shyamalava
experimental part
p. 3115 - 3123
(2010/06/14)

Determination of natural colorants in plant extracts by high-performance liquid chromatography
The determination of the colouring compounds apigenin (1), lawsone (2), juglone (3) and indigotin (4) in plant extracts using HPLC-UV/Vis methods is reported. The methods were applied to the analysis of 1-4 in ethanolic and propylene glycolic extracts originating, respectively, from chamomile (Chamomilla recutita [L] Rauschert, Asteraceae), henna (Lawsonia inermis L., Lythraceae), walnut (Juglans regia L., Juglandaceae) and natural indigo (Indigofera sp., Fabaceae). In the case of the indigo extracts, an optimized acid hydrolysis was applied. HPLC separations were performed on a Hypersil ODS RP18 column using linear gradient elution programs. The detection limits for 1-4 were 0.11, 0.6, 0.10, 0.089 μg mL-1, respectively. The procedure did not involve any sample clean-up methods. The amounts of the colouring compounds ranged from 0.006 (3) to 0.13 mg mL-1 (4) in the ethanolic extracts and from 0.22 (2) to 1.44 mg mL-1 (4) in propylene glycolic extracts. The proposed HPLC methods are advantageous in terms of sample preparation and the selective separation of the compounds. The plant dye extracts are commonly used in hair colouring formulations. The results indicate that the methods developed may serve for the quantitative control of dying plants and cosmetic products.
Gevrenova, Reneta
experimental part
p. 903 - 915
(2010/11/18)

NMR spectroscopic study of the Murex trunculus dyeing process
It is widely accepted that indigo dyes derived from Murex trunculus were used to produce the biblical dyes tekhelet and argaman. We describe a method of following the debromination of natural leucoindigos and their binding to wool using NMR spectroscopy. Debromination is observed prior to reaction with the wool and prior to oxidation. Binding to the wool is shown to occur prior to oxidation. NMR allows the dyeing process to be followed. This, in principle, could be used to correct problems during dyeing that would increase the reliability of the process. Copyright
Hoffman, Rina C.,Zilber, Reut C.,Hoffman, Roy E.
scheme or table
p. 892 - 895
(2011/09/16)

Novel reactivity of dibenzothiophene monooxygenase from bacillus subtilis WU-S2B
Dibenzothiophene monooxygenase (BdsC) from Bacillus subtilis WU-S2B utilized aromatic compounds not having sulfur atoms as substrates. It acted on indole and its derivatives to form indigoid pigments, and also utilized indoline and phenoxazine. In additio
Ohshiro, Takashi,Nakura, Shuhei,Ishii, Yoshitaka,Kino, Kuniki,Kirimura, Kohtaro,Izumi, Yoshikazu
experimental part
p. 2128 - 2130
(2010/06/21)

HIGHER PURITY HYBRID PIGMENTS
A hybrid pigment composition and method of producing the hybrid pigment composition is provided. The hybrid pigment composition includes a purified dye, purified pigment, purified dye intermediate, or purified pigment intermediate and a fibrous clay. The fibrous clay is palygorskite, sepiolite, or a combination thereof. The hybrid pigment composition is produced by reacting the purified dye, purified pigment, purified dye intermediate, or purified pigment intermediate with the fibrous clay.
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Page/Page column 13

(2009/07/03)

Solving the clogging problem: Precipitate-forming reactions in flow
Solids go with the flow: A monodisperse flow in a microreactor provides an efficient method for keeping solid products away from channel walls. The use of a carrier phase, such as mineral oil, hexane, or toluene, enables solids to be synthesized without clogging of the reactor channels. Further injection points can be added to the microreactor to perform multistep syntheses (see picture). (Figure Presented)
Poe, Sarah L.,Cummings, Meredith A.,Haaf, Michael P.,McQuade, D. Tyler
p. 1544 - 1548
(2007/10/03)

Indole hydroxylation by bacterial cytochrome P450 BM-3 and modulation of activity by cumene hydroperoxide
Cytochrome P450 BM-3 from Bacillus megaterium catalyzed NADPH-supported indole hydroxylation under alkaline conditions with homotropic cooperativity toward indole. The activity was also found with the support of H 2O2, tert-butyl hydroperoxide (tBuOOH), or cumene hydroperoxide (CuOOH). Enhanced activity and heterotropic cooperativity were observed in CuOOH-supported hydroxylation, and both the Hill coefficient and substrate concentration required for half-maximal activity in the CuOOH-supported reaction were much lower than those in the H2O 2-, tBuOOH-, or NADPH-supported reactions. CuOOH greatly enhanced NADPH consumption and indole hydroxylation in the NADPH-supported reaction. However, when CuOOH was replaced by tBuOOH or H2O2, heterotropic cooperativity was not observed. Spectral studies also confirmed that CuOOH stimulated indole binding to P450 BM-3. Interestingly, a mutant enzyme with enhanced indole-hydroxylation activity, F87V (Phe87 was replaced by Val), lost homotropic cooperativity towards indole and heterotropic cooperativity towards CuOOH, indicating that the active-site structure affects the cooperativities.
Li, Qing-Shan,Ogawa, Jun,Schmid, Rolf D.,Shimizu, Sakayu
p. 293 - 300
(2007/10/03)

Identification of broad specificity P450CAM variants by primary screening against indole as substrate
High-throughput screening of cytochrome P450CAM libraries, for their ability to oxidise indole to indigo and indirubin, has resulted in the identification of variants with activity towards the structurally unrelated substrate diphenylmethane. The Royal Society of Chemistry 2005.
Celik, Ayhan,Speight, Robert E.,Turner, Nicholas J.
p. 3652 - 3654
(2007/10/03)

A cyclodextrin-based molecular reactor to template the formation of indigoid dyes
N,N′-Bis(6A-deoxy-β-cyclodextrin-6 A-yl)urea behaves as a molecular reactor to bias competing reactions of indoxyl anion and isatin-5-sulfonate in water, to give indigo and indirubin-5′-sulfonate. It appears that the cyclodextrin dimer increases the relative reactivity of the isatin-5-sulfonate, by selectively complexing the reactive form. The molecular host also aligns the isatinsulfonate with indoxyl anion to favour production of indirubin-5′-sulfonate, with the result that the ratio of indigo and indirubin-5′-sulfonate produced is altered by a factor of at least 3500, without a substantial loss of yield.
Harper, Jason B.,Easton, Christopher J.,Lincoln, Stephen F.
p. 5815 - 5818
(2007/10/03)

Directed evolution of the fatty-acid hydroxylase P450 BM-3 into an indole-hydroxylating catalyst
The self-sufficient cytochrome P450 BM-3 enzyme from Bacillus megaterium catalyzes subterminal hydroxylation of saturated long-chain fatty acids and structurally related compounds. Since the primary structure of P450 BM-3 is homologous to that of mammalian P450 type II, it represents an excellent model for this family of enzymes. During studies on the directed evolution of P450 BM-3 into a medium-chain fatty-acid hydroxylase, several mutants, in particular the triple mutant Phe87Val, Leu 188Gln, Ala74Gly, were observed to hydroxylate indole, producing indigo and indiruhin at a catalytic efficiency of 1365M-1s-1 (kcat=2.73 s-1 and Km,=2.0mM). Both products were unequivocally characterized by NMR and MS analysis. Wild-type P450 BM-3 is incapable to hydroxylate indole. These results demonstrate that an enzyme can be engineered to catalyze the transformation of substrates with structures widely divergent from those of its native substrate.
Li, Qing-Shan,Schwaneberg, Ulrich,Fischer, Peter,Schmid, Rolf D.
p. 1531 - 1536
(2007/10/03)

Effects of Organic Solvents on Indigo Formation by Pseudomonas sp. strain ST-200 Grown with High Levels of Indole
The indole tolerance level of Pseudomonas sp. strain ST-200 was 0.25 mg/ml. The level was raised to 4 mg/ml when diphenylmethane was added to the medium to 20% by volume. ST-200 grown in this two-phase culture system containing indole (1 mg/ml) and diphenylmethane (0.2 ml/ml) produced a water-soluble yellow pigment, isatic acid, and two water-insoluble and diphenylmethane-soluble pigments, blue indigo and purple indirubin. The amounts of the water-insoluble pigments corresponded to 0.5% (indigo) and 0.2% (indirubin) of the indole added to the medium. Of the conditions tried, indigo and indirubin were formed only when ST-200 was grown in the two-phase system overlaid with organic solvents with appropriate polarity.
Doukyu, Noriyuki,Arai, Tomonori,Aono, Rikizo
p. 1075 - 1080
(2007/10/03)

Film-forming product for coating solid forms, process for its manufacture and products coated with this film-forming product
The present invention relates to a film-forming product for coating solid forms, to a process for the manufacture of this film-forming product and to products coated with this film-forming product. According to the invention, this film-forming product takes the form of homogeneous granular particles which can easily be dispersed in an aqueous or organic solvent and which make it possible to obtain a uniform non-matt film, and its dry matter comprises: at least one ingestible, non-toxic film-forming substance in an amount of between 30 and 95% by weight; at least one colored pigment in an amount of between 5 and 50% by weight; and if appropriate, at least one edible plasticizer in an amount less than or equal to 30% by weight.
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(2008/06/13)

Transformation of isatin with P4S10 to pentathiepino[6,7-b]indole in one step
Pentathiepino[6,7-b]indole (6) can be isolated from reactions of P4S10 with isatin in pyridine. The structure of 6 has been determined with X-ray crystallography.
Bergman, Jan,Stlhandske, Claes
p. 5279 - 5282
(2007/10/02)

Palladium-catalyzed coupling of 3-indolyl triflate. Syntheses of 3-vinyl and 3-alkynylindoles
Palladium-catalyzed coupling of 1-(phenylsulfonyl)indol-3-yl trifluoromethanesulfonate (triflate) (1) with terminal alkenes and alkynes gives 3-vinyl (2) and 3-alkynylindoles in 45-93% yields. An attempt to generate 2,3-indolyne 22 from 2-trimethylsilyl-3-indolyl triflate 20 gives indigo (23).
Gribble,Conway
p. 2129 - 2141
(2007/10/02)

2-Chloro-3H-indol-3-one and its Reactions with Nucleophiles
The title compound reacts with N- and S-nucleophiles to form 3-substituted indol-2-ones, but with C-nucleophiles to afford either these or the corresponding 2-substituted indol-3-ones.This dichotomy of behavior is documented and rationalized.
Katritzky, Alan R.,Fan, Wei-Qiang,Koziol, Anna E.,Palenik, Gus J.
p. 821 - 828
(2007/10/02)

Indigo blue-colored bioabsorbable surgical fibers and production process thereof
Blue-colored bioabsorbable surgical fibers are obtained by adding and dispersing a bioabsorbable polymer, which is selected from polyglycolic acid, poly(l-lactic acid) and glycolic acid-l-lactic acid copolymers all of which are useful as surgical fibers, and indigo in a non-aqueous organic solvent having low solubility for the polymer and indigo, heating the resultant dispersion at a temperature below 120° C. to distill off the solvent, thereby to obtain a master batch with the indigo incorporated therein at a high concentration, mixing and kneading the master batch with a fresh supply of the polymer, and then spinning the resultant polymer mixture.
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(2008/06/13)

2,2-Disubstituted-1,2-dihydro-3H-indol-3-ones by Base- and Thermal-induced Cyclisations of o-Azidophenyl s-Alkyl Ketones and o-Azidobenzoyl Esters
o-Azidophenyl s-alkyl ketones in ethanolic potassium hydroxide at room temperature undergo loss of nitrogen and cyclisation to 2,2-dialkyl-1,2-dihydro-3H-indol-3-ones in high yield.Kinetic data (E(act.) 62.4 and 71.6 kJ mol-1, respectively) obtained for the o-azidophenylisopropyl and o-azidophenylcyclohexyl ketones support an assisted nitrogen loss from the azide via the enolate ion, rather than a nitrene reaction. 1,2-Dihydro-3H-indol-3-ones, along with in some cases 2,1-benzisoxazoles, have been obtained by the thermolysis and spray vacuum pyrolysis of other o-azidophenyl alkyl ketones, diethyl o-azidobenzoyl malonate, and ethyl o- azidobenzoyl(phenyl)acetate.
Azadi-Ardakani, Manouchehr,Alkhader, Mohamed A.,Lippiatt, John H.,Patel, Dalpat I.,Smalley, Robert K.,Higson, Susan
p. 1107 - 1112
(2007/10/02)

INTRODUCTION OF ACYL SUBSTITUTENTS AT POSITION 2 OF THE INDOLINONE RING
The acylation of 1-acetyl-3-indolinone at position 2 of the heterocycle was realized by the action of acetic and propionic anhydride in the presence of sulfuric acid.It was shown that the reaction takes place with a high yield through an O-acylation and a Fries rearrangement stage.The Fries rearrangement was used to convert the 1-acetyl-3-hydroxybenzoylindole into 1-acetyl-2-benzoyl-3-indolinone.The same β-diketone and also 1-acetyl-2-(p-chlorobenzoyl)-3-indolinone were obtained by the action of a mixture of acetic anhydride and sulfuric acid on the respective 1-acetyl-2-arylidene- 3-indolinones. 1-Acetyl-3-formyl-3-chloroindole was obtained by the reaction of 1-acetyl-3-indolinone with the Vilsmeier complex obtained from DMFA and phosphorus oxychloride.It was deacylated to 2-formyl-3-chloroindole.
Velezheva, V. S.,Smushkevich, V. Yu.,Romanova, O. B.,Kurkovskaya, L. N.,Suvorov, N. N.
p. 2186 - 2193
(2007/10/02)

THE STRUCTURE AND PROPERTIES OF SOME INDOLIC CONSTITUENTS IN COUROUPITA GUIANENSIS Aubl.
Extraction of the dried fruits of the cannon ball tree, Couroupita guianensis Aubl., yielded 6,12-dihydro-6,12-dioxoindoloquinazoline (tryptanthrin), 1a as well as indigo (7) indirubin (8a) and isatin.Compound 1a could readily be synthesized by condensation of isatin with isatoic anhydride (6) in pyridine.
Bergman, Jan,Lindstroem, Jan-Olof,Tilstam, Ulf
p. 2879 - 2882
(2007/10/02)

Syntheses and Properties of Pyrrolindigo Compounds
4,4',5,5',6,6',7,7'-Octahydroindigo (9c), 4,4'-dibutyl-5,5'-dimethylpyrrolindigo (9a) and di(cyclopenta)pyrrolindigo (9d) as well as the condensation products from 2-pyrrolin-4-ones with benzaldehyde, isatin, glyoxale, and 2-methoxy-3-indolone, plus N-methyl- and N,N'-dimethylderivatives of 9c and tetrahydroindigo 31 were all synthesized and compared with other indigoids especially the corresponding benzoannelated compounds.The unusul behavior of N-methylindigoids is discussed.In the boron chelate 39 of 1-methyl-4,5,6,7-tetrahydroindigo the structure of a fixed tautomeric indigo is approached.
Pfeiffer, Georg,Bauer, Helmut
p. 564 - 589
(2007/10/02)