875-74-1Relevant articles and documents
Formation of Quasi-racemic Diastereoisomeric Salts as a Structural Cause for Efficient Optical Resolution
Fogassy, Elemer,Kozma, David
, p. 5069 - 5070 (1995)
During optical resolutions, when the resolving agent is structurally similar to the racemate, very efficient resolution can be achieved, because of the formation of quasi-racemic diastereoisomeric salts, in which the enantiomers have opposite configuration.
The Methyl Ester of α-Aminophenylacetic Acid: pH-Dependence and Phosphate Catalysis of Hydrolysis
Blinkovsky, Alexander M.,Galaev, Igor Yu.,Svedas, Vytas K.
, p. 1537 - 1540 (1986)
The dependence of the rate of spontaneous (non-enzymic) hydrolysis of α-aminophenylacetic acid methyl ester on the acidity of a medium was studied over the pH range 0.95-11.6.The mono- and dianion of phosphate was found to have a catalytic effect on this reaction, according to the mechanism of general base catalysis.Catalysis of the protonated substrate from hydrolysis by different phosphate ions, the second molecule of water, and the hydroxide ion follows the Broensted catalysis law with the slope 0.60.At a strong alkaline pH, phosphate slows down the ester hydrolysis, probably due to the formation of an ester-phosphate complex; the calculated dissociation constant is 4.2xE-3M, while the ratio of the hydrolysis rate constants for free ester and its phosphate complex is 7.7.
Highly Stable Zr(IV)-Based Metal-Organic Frameworks for Chiral Separation in Reversed-Phase Liquid Chromatography
Jiang, Hong,Yang, Kuiwei,Zhao, Xiangxiang,Zhang, Wenqiang,Liu, Yan,Jiang, Jianwen,Cui, Yong
supporting information, p. 390 - 398 (2021/01/13)
Separation of racemic mixtures is of great importance and interest in chemistry and pharmacology. Porous materials including metal-organic frameworks (MOFs) have been widely explored as chiral stationary phases (CSPs) in chiral resolution. However, it remains a challenge to develop new CSPs for reversed-phase high-performance liquid chromatography (RP-HPLC), which is the most popular chromatographic mode and accounts for over 90% of all separations. Here we demonstrated for the first time that highly stable Zr-based MOFs can be efficient CSPs for RP-HPLC. By elaborately designing and synthesizing three tetracarboxylate ligands of enantiopure 1,1′-biphenyl-20-crown-6, we prepared three chiral porous Zr(IV)-MOFs with the framework formula [Zr6O4(OH)8(H2O)4(L)2]. They share the same flu topological structure but channels of different sizes and display excellent tolerance to water, acid, and base. Chiral crown ether moieties are periodically aligned within the framework channels, allowing for stereoselective recognition of guest molecules via supramolecular interactions. Under acidic aqueous eluent conditions, the Zr-MOF-packed HPLC columns provide high resolution, selectivity, and durability for the separation of a variety of model racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation. DFT calculations suggest that the Zr-MOF provides a confined microenvironment for chiral crown ethers that dictates the separation selectivity.
D-Phenylglycine aminotransferase (d-PhgAT)-substrate scope and structural insights of a stereo-inverting biocatalyst used in the preparation of aromatic amino acids
Akhtar, M. Kalim,Campopiano, Dominic J.,De Cesare, Silvia,Loake, Gary J.,Marles-Wright, Jon,Serpico, Annabel
, p. 6533 - 6543 (2020/11/13)
Enantiopure amines are key building blocks in the synthesis of many pharmaceuticals, so a route to their production is a current goal for biocatalysis. The stereo-inverting d-phenylglycine aminotransferase (d-PhgAT), isolated from Pseudomonas stutzeri ST-201, catalyses the reversible transamination from l-glutamic acid to benzoylformate, yielding α-ketoglutarate and d-phenylglycine (d-Phg). Detailed kinetic analysis revealed a range of amine donor and acceptor substrates that allowed the synthesis of enantiopure aromatic d-amino acids at a preparative scale. We also determined the first X-ray crystal structure of d-PhgAT with its bound pyridoxal 5′-phosphate (PLP) cofactor at 2.25 ? resolution. A combination of structural analysis and site-directed mutagenesis of this class III aminotransferase revealed key residues that are potentially involved in the dual substrate recognition, as well as controlling the stereo-inverting behaviour of d-PhgAT. Two arginine residues (Arg34 and Arg407) are involved in substrate recognition within P and O binding pockets respectively. These studies lay the foundation for further enzyme engineering and promote d-PhgAT as a useful biocatalyst for the sustainable production of high value, aromatic d-amino acids. This journal is
Deracemization and stereoinversion to aromatic d-amino acid derivatives with ancestral l-amino acid oxidase
Nakano, Shogo,Minamino, Yuki,Hasebe, Fumihito,Ito, Sohei
, p. 10152 - 10158 (2019/10/19)
Enantiomerically pure amino acid derivatives could be foundational compounds for peptide drugs. Deracemization of racemates to l-amino acid derivatives can be achieved through the reaction of evolved d-amino acid oxidase and chemical reductants, whereas deracemization to d-amino acid derivatives has not progressed due to the difficulty associated with the heterologous expression of l-amino acid oxidase (LAAO). In this study, we succeeded in developing an ancestral LAAO (AncLAAO) bearing broad substrate selectivity (13 l-amino acids) and high productivity through an Escherichia coli expression system (50.7 mg/L). AncLAAO can be applied to perform deracemization to d-amino acids in a similar way to deracemization to l-amino acids. In fact, full conversion (>99% ee, d-form) could be achieved for 16 racemates, including nine d,l-Phe derivatives, six d,l-Trp derivatives, and a d,l-phenylglycine. Taken together, we believe that AncLAAO could be a key enzyme to obtain optically pure d-amino acid derivatives in the future.
Ultrasound-Controlled Chiral Separation of Four Amino Acids and 2,2,2-Trifluoro-1-(9-anthryl)ethanol
Lee, Jae Hwan,Ryoo, Jae Jeong
, p. 146 - 149 (2019/02/07)
Chiral separation of 4-hydroxyphenylglycine, phenylglycine, tryptophan, methionine, and 2,2,2-trifluoro-1-(9-anthryl)ethanol (TFAE) was performed under ultrasound reduction at room temperature and high temperature (50 °C). At high temperature (50 °C), both α and Rs were improved slightly under ultrasound reduction as compared to those under non-ultrasonic and ultrasonic irradiation (50 watt/L) conditions. Even at low temperatures, the largest α was observed under ultrasound reduction conditions, except in the case of methionine. However, at low temperature, Rs was reduced under ultrasound (50 watt/L) irradiation, but was improved under ultrasound reduction rather than under the continuous ultrasonic irradiation. Similar to the fact that gradient elution (based on solvent polarity) can improve α, ultrasound reduction can improve α and Rs. Ultrasound reduction is demonstrated to aid the rapid separation of chiral compounds with improved resolution, especially, at high temperatures. Although chromatographic separation using ultrasound has been rarely dealt with until now, ultrasound can be used as an external field in chromatography.
A high-throughput pH-based colorimetric assay: application focus on alpha/beta hydrolases
Paye, Mariétou F.,Rose, Harrison B.,Robbins, John M.,Yunda, Diana A.,Cho, Seonggeon,Bommarius, Andreas S.
, p. 80 - 90 (2018/03/24)
Research involving α/β hydrolases, including α-amino acid ester hydrolase and cocaine esterase, has been limited by the lack of an online high throughput screening assay. The development of a high throughput screening assay capable of detecting α/β hydrolase activity toward specific substrates and/or chemical reactions (e.g., hydrolysis in lieu of amidase activity and/or synthesis instead of thioesterase activity) is of interest in a broad set of scientific questions and applications. Here we present a general framework for pH-based colorimetric assays, as well as the mathematical considerations necessary to estimate de novo the experimental response required to assign a ‘hit’ or a ‘miss,’ in the absence of experimental standard curves. This combination is valuable for screening the hydrolysis and synthesis activity of α/β hydrolases on a variety of substrates, and produces data comparable to the current standard technique involving High Performance Liquid Chromatography (HPLC). In contrast to HPLC, this assay enables screening experiments to be performed with greater efficiency.
Enantioselective synthesis of amines via reductive amination with a dehydrogenase mutant from Exigobacterium sibiricum: Substrate scope, co-solvent tolerance and biocatalyst immobilization
L?we, Jana,Ingram, Aaron A.,Gr?ger, Harald
, p. 1387 - 1392 (2018/03/21)
In recent years, the reductive amination of ketones in the presence of amine dehydrogenases emerged as an attractive synthetic strategy for the enantioselective preparation of amines starting from ketones, an ammonia source, a reducing reagent and a cofactor, which is recycled in situ by means of a second enzyme. Current challenges in this field consists of providing a broad synthetic platform as well as process development including enzyme immobilization. In this contribution these issues are addressed. Utilizing the amine dehydrogenase EsLeuDH-DM as a mutant of the leucine dehydrogenase from Exigobacterium sibiricum, a range of aryl-substituted ketones were tested as substrates revealing a broad substrate tolerance. Kinetics as well as inhibition effects were also studied and the suitability of this method for synthetic purpose was demonstrated with acetophenone as a model substrate. Even at an elevated substrate concentration of 50 mM, excellent conversion was achieved. In addition, the impact of water-miscible co-solvents was examined, and good activities were found when using DMSO of up to 30% (v/v). Furthermore, a successful immobilization of the EsLeuDH-DM was demonstrated utilizing a hydrophobic support and a support for covalent binding, respectively, as a carrier.
Structure-guided engineering of: Meso -diaminopimelate dehydrogenase for enantioselective reductive amination of sterically bulky 2-keto acids
Cheng, Xinkuan,Chen, Xi,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
, p. 4994 - 5002 (2018/10/17)
meso-Diaminopimelate dehydrogenase (DAPDH) and mutant enzymes are an excellent choice of biocatalysts for the conversion of 2-keto acids to the corresponding d-amino acids. However, their application in the enantioselective reductive amination of bulky 2-keto acids, such as phenylglyoxylic acid, 2-oxo-4-phenylbutyric acid, and indole-3-pyruvic acid, is still challenging. In this study, the structure-guided site-saturation mutagenesis of a Symbiobacterium thermophilum DAPDH (StDAPDH) gave rise to a double-site mutant W121L/H227I, which showed dramatically improved enzyme activities towards various 2-keto acids including these sterically bulky substrates. Several d-amino acids were prepared in optically pure form. The molecular docking of substrates into the active sites of wild-type and mutant W121L/H227I enzymes revealed that the substrate binding cavity of the mutant enzyme was reshaped to accommodate these bulky substrates, thus leading to higher enzyme activity. These results lay a foundation for further shaping the substrate binding pocket and manipulating the interactions between the substrate and binding sites to access highly active d-amino acid dehydrogenases for the preparation of synthetically challenging d-amino acids.
RETRACTED ARTICLE: Chemoenzymatic Method for Enantioselective Synthesis of (R)-2-Phenylglycine and (R)-2-Phenylglycine Amide from Benzaldehyde and KCN Using Difference of Enzyme Affinity to the Enantiomers
Kawahara, Nobuhiro,Asano, Yasuhisa
, p. 5014 - 5020 (2018/10/20)
In general, enzymatic and chemoenzymatic methods for asymmetric synthesis of α-amino acids are performed using highly enantioselective enzymes. The enzymatic reactions using α-aminonitrile as a starting material have been performed using reaction conditions apart from the chemical Strecker synthesis. We developed a new chemoenzymatic method for the asymmetric synthesis of α-amino acids from aldehydes and KCN by performing Strecker synthesis and nitrilase reaction in the same reaction mixture. Nitrilase AY487533 that showed rather low enantioselectivity in hydrolysis of 2-phenylglycinonitrile (2PGN) to 2-phenylglycine (2PG) was utilized in the hydrolysis of aminonitrile formed from benzaldehyde and KCN via 2PGN by Strecker synthesis, preferentially synthesizing (R)-2PG with more than 95 % yield and enantiomeric excess (ee). The method was also utilized for the synthesis of (R)-2-phenylglycine amide ((R)-2PGNH2) from benzaldehyde and KCN by the chemoenzymatic reaction in the presence of a mutated nitrilase AY487533W186A, which catalyzes the conversion of 2PGN to 2PGNH2.
