816-66-0Relevant academic research and scientific papers
One-step Synthesis of α-Keto Acids from Racemic Amino Acids by A Versatile Immobilized Multienzyme Cell-free System
Orrego, Alejandro H.,López-Gallego, Fernando,Espaillat, Akbar,Cava, Felipe,Guisan, José M.,Rocha-Martin, Javier
, p. 3002 - 3011 (2018)
The elevated value of α-keto acids has pushed scientists to explore more efficient and less expensive alternatives for their synthesis. In this work, an immobilized tri-enzyme system that produced α-keto acids in “one-pot” from l- or racemic mixtures of diverse amino acids was presented. The system combined a broad-spectrum amino acid racemase (BsrV), a d-amino acid oxidase (DAAO) and catalase (CAT). BsrV racemized l-amino acids into their d-enantiomers, DAAO catalyzed the stereospecific oxidative deamination of the d-amino acids into their corresponding α-keto acids, ammonium ion, and H2O2. Finally, CAT converted the inactivating H2O2 into H2O and O2, which can be reused by the oxidase reaction. BsrV thermal stability was improved 3,300-fold by immobilizing the enzyme on glyoxyl-activated agarose beads. DAAO and CAT were co-immobilized on agarose beads functionalized with glutaraldehyde groups for enhancing their stabilities and eliminating H2O2 in a much more effective way. To show the versatility of this system, racemic mixtures of amino acids were converted in their corresponding α-keto acids. The coupling of the three immobilized enzymes permitted conversions of approximately 99 % through a dynamic kinetic resolution process. This system conserved 100 % of its initial effectiveness after 8 reaction cycles. Collectively, our innovative tri-enzyme system for the synthesis of α-keto acids opens the door for a cheapening in the production of many pharmaceutical and cosmetics.
Structural and functional evolution of isopropylmalate dehydrogenases in the leucine and glucosinolate pathways of Arabidopsis thaliana
He, Yan,Galant, Ashley,Pang, Qiuying,Strul, Johanna M.,Balogun, Sherifat F.,Jez, Joseph M.,Chen, Sixue
, p. 28794 - 28801 (2011)
The methionine chain-elongation pathway is required for aliphatic glucosinolate biosynthesis in plants and evolved from leucine biosynthesis. In Arabidopsis thaliana, three 3-isopropylmalate dehydrogenases (AtIPMDHs) play key roles in methionine chain-elongation for the synthesis of aliphatic glucosinolates (e.g. AtIPMDH1) and leucine (e.g. AtIPMDH2 and AtIPMDH3). Here we elucidate the molecular basis underlying the metabolic specialization of these enzymes. The 2.25 A° resolution crystal structure of AtIPMDH2 was solved to provide the first detailed molecular architecture of a plant IPMDH. Modeling of 3-isopropylmalate binding in the AtIPMDH2 active site and sequence comparisons of prokaryotic and eukaryotic IPMDH suggest that substitution of one active site residue may lead to altered substrate specificity and metabolic function. Sitedirected mutagenesis of Phe-137 to a leucine in AtIPMDH1 (AtIPMDH1-F137L) reduced activity toward 3-(2′-methylthio)-ethylmalate by 200-fold, but enhanced catalytic efficiency with 3-isopropylmalate to levels observed with AtIPMDH2 and AtIPMDH3. Conversely, the AtIPMDH2-L134F and AtIPMDH3-L133F mutants enhanced catalytic efficiency with 3-(2′-methylthio)ethylmalate ～100-fold and reduced activity for 3-isopropylmalate. Furthermore, the altered in vivo glucosinolate profile of an Arabidopsis ipmdh1 T-DNA knock-out mutant could be restored to wild-type levels by constructs expressing AtIPMDH1, AtIPMDH2-L134F, or AtIPMDH3-L133F, but not by AtIPMDH1-F137L. These results indicate that a single amino acid substitution results in functional divergence of IPMDH in planta to affect substrate specificity and contributes to the evolution of specialized glucosinolate biosynthesis from the ancestral leucine pathway.
Stereospecificity of the Hydride Transfer Reaction Catalyzed by Isopropylmalate Dehydrogenase of Thermophilic Bacteria Thermus thermophilius
Yamada, Tohru,Kakinuma, Katsumi,Endo, Toyoshige,Oshima, Tairo
, p. 1749 - 1752 (1987)
Nuclear magnetic resonance studied on the NAD-dependent reaction catalyzed by isopropylmalate dehydrogenase from T. thermophilius HB8 revealed that pro R specific (A specific) hydride transfer from the substrate to the nicotinamide ring is involved during the said oxido-reduction.
Coenzyme activity of NAD analogs for 3-isopropylmalate dehydrogenase from Thermus thermophilus HB8
Chiba, Akira,Eguchi, Tadashi,Oshima, Tairo,Kakinuma, Katsumi
, p. 1647 - 1649 (1999)
In order to elucidate the enzyme-substrate-cofactor interaction in 3-isopropylmalate dehydrogenase, the coenzyme activity of NAD analogs which have a 3-substituted pyridine ring was examined. Analogs 3-5 showed diminished kcat values compared with those of NAD+, whereas thiocarboxamide 2 was almost as equally active as NAD+. This suggests that the NH2 functionality of NAD+ is more important for the catalysis of IPMDH than a carbonyl group.
Overproduction and substrate specificity of 3-isopropylmalate dehydrogenase from Thiobacillus ferrooxidans.
Matsunami,Kawaguchi,Inagaki,Eguchi,Kakinuma,Tanaka
, p. 372 - 373 (1998)
We constructed an overexpression system in Escherichia coli of the leuB gene coding for 3-isopropylmalate dehydrogenase in Thiobacillus ferrooxidans. E. coli harboring the plasmid we constructed, pKK leuB1, produced 17-fold the enzyme protein of the expression system previously used for purification. The substrate specificity of the enzyme was analyzed with synthetic (2R, 3S)-3-alkylmalates. The 3-isopropylmalate dehydrogenase of Thiobacillus ferrooxidans had broad specificity toward the alkylmalates.
Palladium-Catalyzed β-Arylation of α-Keto Esters
Zavesky, Blane P.,Bartlett, Samuel L.,Johnson, Jeffrey S.
, p. 2126 - 2129 (2017)
A catalyst system derived from commercially available Pd2(dba)3 and PtBu3 has been applied to the coupling of α-keto ester enolates and aryl bromides. The reaction provides access to an array of β-stereogenic α-keto esters. When the air-stable ligand precursor PtBu3·HBF4 is employed, the reaction can be carried out without use of a glovebox. The derived products are of broad interest given the prevalence of the α-keto acid substructure in biologically important molecules.
Scalable and Selective β-Hydroxy-α-Amino Acid Synthesis Catalyzed by Promiscuous l-Threonine Transaldolase ObiH
Buller, Andrew R.,Doyon, Tyler J.,Grieger, Abbigail M.,Kim, Maeve,Kumar, Prasanth,Madigan, Cormac,Stitgen, Abigail,Thein, Sierra,Willoughby, Patrick H.
, (2021/11/23)
Enzymes from secondary metabolic pathways possess broad potential for the selective synthesis of complex bioactive molecules. However, the practical application of these enzymes for organic synthesis is dependent on the development of efficient, economical, operationally simple, and well-characterized systems for preparative scale reactions. We sought to bridge this knowledge gap for the selective biocatalytic synthesis of β-hydroxy-α-amino acids, which are important synthetic building blocks. To achieve this goal, we demonstrated the ability of ObiH, an l-threonine transaldolase, to achieve selective milligram-scale synthesis of a diverse array of non-standard amino acids (nsAAs) using a scalable whole cell platform. We show how the initial selectivity of the catalyst is high and how the diastereomeric ratio of products decreases at high conversion due to product re-entry into the catalytic cycle. ObiH-catalyzed reactions with a variety of aromatic, aliphatic and heterocyclic aldehydes selectively generated a panel of β-hydroxy-α-amino acids possessing broad functional-group diversity. Furthermore, we demonstrated that ObiH-generated β-hydroxy-α-amino acids could be modified through additional transformations to access important motifs, such as β-chloro-α-amino acids and substituted α-keto acids.
Chemoenzymatic Production of Enantiocomplementary 2-Substituted 3-Hydroxycarboxylic Acids from l-α-Amino Acids
Pickl, Mathias,Marín-Valls, Roser,Joglar, Jesús,Bujons, Jordi,Clapés, Pere
, p. 2866 - 2876 (2021/04/14)
A two-enzyme cascade reaction plus in situ oxidative decarboxylation for the transformation of readily available canonical and non-canonical l-α-amino acids into 2-substituted 3-hydroxycarboxylic acid derivatives is described. The biocatalytic cascade consisted of an oxidative deamination of l-α-amino acids by an l-α-amino acid deaminase from Cosenzaea myxofaciens, rendering 2-oxoacid intermediates, with an ensuing aldol addition reaction to formaldehyde, catalyzed by metal-dependent (R)- or (S)-selective carboligases namely 2-oxo-3-deoxy-l-rhamnonate aldolase (YfaU) and ketopantoate hydroxymethyltransferase (KPHMT), respectively, furnishing 3-substituted 4-hydroxy-2-oxoacids. The overall substrate conversion was optimized by balancing biocatalyst loading and amino acid and formaldehyde concentrations, yielding 36–98% aldol adduct formation and 91–98% ee for each enantiomer. Subsequent in situ follow-up chemistry via hydrogen peroxide-driven oxidative decarboxylation afforded the corresponding 2-substituted 3-hydroxycarboxylic acid derivatives. (Figure presented.).
Total Synthesis of the Natural Herbicide MBH-001 and Analogues
Barber, David M.,D?ller, Uwe,Dietrich, Hansj?rg,Hoffmann, Michael G.,Kocakaya, Tamer,Kuhn, Birgit,Maier, Martin E.,Morkunas, Marius,Schmutzler, Dirk,Schnatterer, Stefan
, p. 2271 - 2290 (2020/04/23)
The first total synthesis of the natural herbicide MBH-001 (1) is reported. Structurally it is a 2-methyloxazol-5(2H)-one with a (1-hydroxyethyl) substituent at the 2-position. By relying on cyclic nitrones, a flexible route to MBH-001 and relevant analogues was developed. Key steps include the reaction of a 2-hydroxyimino ester with an aldehyde to form a 5-oxo-2,5-dihydrooxazole 3-oxide. In an aldol-type reaction, the anion of these cyclic nitrones reacted with an aldehyde at the 2-position. A final reduction of the nitrone to the corresponding imine using zinc led to the target compounds. The cyclic nitrones are also accessible by reacting an α-keto acid with an oxime. These two versatile synthetic routes enabled us to prepare the first MBH-001 analogues for structure activity relationship analysis of the herbicidal efficacy. Thus, furthering our aim of developing new herbicides to tackle the ever-growing problem of weed resistance.
Exploration of Transaminase Diversity for the Oxidative Conversion of Natural Amino Acids into 2-Ketoacids and High-Value Chemicals
Chen, Yanchun,Cui, Xuexian,Cui, Yinglu,Li, Chuijian,Li, Ruifeng,Li, Tao,Sun, Jinyuan,Wu, Bian,Zhu, Tong
, p. 7950 - 7957 (2020/08/21)
The use of 2-ketoacids is very common in feeds, food additives, and pharmaceuticals, and 2-ketoacids are valuable precursors for a plethora of chemically diverse compounds. Biocatalytic synthesis of 2-ketoacids starting from l-amino acids would be highly desirable because the substrates are readily available from biomass feedstock. Here, we report bioinformatic exploration of a series of aminotransferases (ATs) to achieve the desired conversion. Thermodynamic control was achieved by coupling an l-glutamate oxidation reaction in the cascade for the recycling of the amine acceptor. These enzymes were able to convert a majority of proteinogenic amino acids into the corresponding 2-ketoacids with high conversion (up to 99percent) and atom-efficiency. Furthermore, this enzyme cascade was extendable, and one-pot two-step processes were established for the synthesis of d-amino acids and N-methylated amino acids, achieving great overall conversion (up to 99percent) and high ee values (>99percent). These developed enzymatic methodologies offer convenient routes for utilizing amino acids as synthetic reagents.
