56-12-2Relevant articles and documents
Enhancing effect of macroporous adsorption resin on gamma-aminobutyric acid production by Enterococcus faecium in whole-cell biotransformation system
Yang, Sheng-Yuan,Liu, Shu-Min,Jiang, Min,Wang, Biao-Shi,Peng, Luo-Hui,Zeng, Chan
, p. 771 - 780 (2020)
Gamma-aminobutyric acid (GABA) biosynthesis depended to a great extent on the biotransformation characterization of glutamate decarboxylase (GAD) and process conditions. In this paper, the enhancing effect of D101 macroporous adsorption resin (MAR) on the GABA production was investigated based on the whole-cell biotransformation characterization of Enterococcus faecium and adsorption characteristics of D101 MAR. The results indicated that the optimal pH for reaction activity of whole-cell GAD and pure GAD was 4.4 and 5.0, respectively, and the pH range retained at least 50% of GAD activity was from 4.8 to 5.6 and 4.0–4.8, respectively. No substrate inhibition effect was observed on both pure GAD and whole-cell GAD, and the maximum activity could be obtained when the initial L-glutamic acid (L-Glu) concentration exceeded 57.6?mmol/L and 96.0?mmol/L, respectively. Besides, GABA could significantly inhibit the activity of whole-cell GAD rather than pure GAD. When the initial GABA concentration of the reaction solution remained 100?mmol/L, 33.51 ± 9.11% of the whole-cell GAD activity was inhibited. D101 MAR exhibited excellent properties in stabilizing the pH of the conversion reaction system, supplementing free L-Glu and removing excess GABA. Comparison of the biotransformation only in acetate buffer, the GABA production, with 50?g/100?mL of D101 MAR, was significantly increased by 138.71 ± 5.73%. D101 MAR with pre-adsorbed L-Glu could significantly enhance the production of GABA by gradual replenishment of free L-Glu, removing GABA and maintaining the pH of the reaction system, which would eventually make the GABA production more economical and eco-friendly.
ENZYMATIC SYNTHESIS OF γ-AMINOBUTYRIC ACID USING IMMOBILIZED L-GLUTAMATE DECARBOXYLASE
Yanushyavichyute, R. P.,Paulyukonis, A. B.,Kazlauskas, D. A.
, p. 246 (1983)
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Mechanistic aspects of uncatalyzed and ruthenium(III) catalyzed oxidation of DL-ornithine monohydrochloride by silver(III) periodate complex in aqueous alkaline medium
Malode, Shweta J.,Abbar, Jyothi C.,Nandibewoor, Sharanappa T.
, p. 2430 - 2442 (2010)
The oxidation of an amino acid, DL-ornithine monohydrochloride (OMH) by diperiodatoargentate(III) (DPA) was carried out both in the absence and presence of ruthenium(III) catalyst in alkaline medium at 25°C and a constant ionic strength of 0.10 mol dm-3 spectrophorometrically. The reaction was of first order in both catalyzed and uncatalyzed cases, with respect to [DPA] and was less than unit order in [OMH] and negative fraction in [alkali]. The order with respect to [OMH] changes from first order to zero order as the [OMH] increases. The order with respect to Ru(III) was unity. The uncatalyzed reaction in alkaline medium has been shown to proceed via a DPA-OMH complex, which decomposes in a rate determining step to give the products. Where as in catalyzed reaction, it has been shown to proceed via a Ru(III)-OMH complex, which further reacts with two molecules of DPA in a rate determining step to give the products. The reaction constants involved in the different steps of the mechanisms were calculated for both the reactions. The catalytic constant (Kcat.const.) was also calculated for catalyzed reaction at different temperatures. The activation parameters with respect to slow step of the mechanism and also the thermodynamic quantities were determined.
Lactams in sulfuric acid. The mechanism of amide hydrolysis in weak to moderately strong aqueous mineral acid media
Cox, Robin A.
, p. 649 - 656 (1998)
Reaction rate constants obtained in moderately concentrated sulfuric acid for the hydrolysis of simple lactams of ring sizes five, six, seven, and eight as a function of acidity and temperature have been analyzed using the excess acidity kinetic method. The basicity constants for these substrates have been recalculated; the 13C NMR spectra used to obtain these values are very sensitive to medium effects. It was found that the basicities of the lactams at 0.003-0.1 M lactam concentration were over half a pK unit more basic than they were at 0.5 M lactam, presumably because of the medium effect. Apart from this, the rate constant results obtained at different times by different groups using different techniques for monitoring the kinetics are in adequate agreement. The excess acidity analysis showed that the kinetics could be fitted according to the 'three-water-molecule followed by one-water-molecule' mechanistic scenario previously found, or could just as well be fitted by a 'one-water-molecule followed by unknown mechanism' scenario, with the mechanistic change taking place at 50 wt.% sulfuric acid for all the substrates. Other evidence makes the latter seem the more likely possibility of the two, and activation parameters based upon the 'one-water- molecule' process were determined. Sufficient data points to enable the unknown mechanism to be established were not present; possible mechanisms applicable in media more concentrated than 50 wt.% sulfuric acid are discussed. Previously obtained values of the parameter r, the number of water molecules involved with the substrate in A2 processes, are now questionable.
Osmium(VIII) catalyzed oxidation of DL-ornithine monohydrochloride by a new oxidant, diperiodatoargentate(III) in aqueous alkaline medium
Malode, Shweta J.,Abbar, Jyothi C.,Nandibewoor, Sharanappa T.
, p. 246 - 256 (2010)
The kinetics of osmium(VIII) (Os(VIII)) catalyzed oxidation of DL-ornithine monohydrochloride (OMH) by diperiodatoargentate(III) (DPA) in alkaline medium at 298 K and a constant ionic strength of 0.10 mol dm-3 was studied spectrophotometrically. The stoichiometry is, i.e., [OMH]:[DPA] [image omitted] 1:2. The main products were identified by spot tests, IR, 1H NMR, GC-MS spectral studies. A suitable mechanism is proposed. The reaction constants involved in the different steps of the mechanism are calculated. The catalytic constant (Kc) was also calculated for Os(VIII) catalysis at different temperatures. The active species of catalyst and oxidant have been identified. Copyright Taylor & Francis Group, LLC.
Kinetic and mechanistic aspects of osmium(VIII) catalyzed oxidation of DLornithine by copper(iii) periodate complex in aqueous alkaline medium
Abbar, Jyothi C.,Malode, Shweta J.,Nandibewoor, Sharanappa T.
, p. 865 - 882 (2010)
The oxidation of DL-ornithine monohydrochloride (OMH) by diperiodatocuprate(III) (DPC) has been investigated in the presence of osmium(VIII) catalyst in aqueous alkaline medium at a constant ionic strength of 0.20 mol dm-3 spectrophotometrically. The reaction exhibits 1:4 stoichiometry i.e., [OMH]: [DPC]. The order of the reaction with respect to [DPC] was unity while the order with respect to [OMH] was less than unity over the concentration range studied. The rate increased with an increase in [OH -] and decreased with an increase in [IO4-]. The order with respect to [Os(VIII)] was unity. The reaction rates revealed that Os(VIII) catalyzed reaction was about nine-fold faster than the uncatalyzed reaction. The oxidation products were identified by spectral analysis. Suitable mechanism has been proposed. The reaction constants involved in the different steps of the reaction mechanism were calculated. The catalytic constant (KC) was also calculated at different temperatures. The activation parameters with respect to slow step of the mechanism and also the thermodynamic quantities were determined. Kinetic experiments suggest that [OsO4(OH) 2]2- is the reactive Os(VIII) species and [Cu(H 2IO6)(H2O)2] is the reactive copper(III) species. by Oldenbourg Wissenschaftsverlag, Muenchen.
An Integrated Cofactor/Co-Product Recycling Cascade for the Biosynthesis of Nylon Monomers from Cycloalkylamines
Sarak, Sharad,Sung, Sihyong,Jeon, Hyunwoo,Patil, Mahesh D.,Khobragade, Taresh P.,Pagar, Amol D.,Dawson, Philip E.,Yun, Hyungdon
, p. 3481 - 3486 (2020/12/17)
We report a highly atom-efficient integrated cofactor/co-product recycling cascade employing cycloalkylamines as multifaceted starting materials for the synthesis of nylon building blocks. Reactions using E. coli whole cells as well as purified enzymes produced excellent conversions ranging from >80 and 95 % into desired ω-amino acids, respectively with varying substrate concentrations. The applicability of this tandem biocatalytic cascade was demonstrated to produce the corresponding lactams by employing engineered biocatalysts. For instance, ?-caprolactam, a valuable polymer building block was synthesized with 75 % conversion from 10 mM cyclohexylamine by employing whole-cell biocatalysts. This cascade could be an alternative for bio-based production of ω-amino acids and corresponding lactam compounds.
METHODS FOR IMPROVING YIELDS OF L-GLUFOSINATE
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Page/Page column 33, (2020/03/29)
Compositions and methods for the production of L-glufosinate are provided. The method involves converting racemic glufosinate to the L-glufosinate enantiomer or converting PRO to L-glufosinate in an efficient manner. In particular, the method involves the specific amination of PRO to L-glufosinate, using L-glutamate, racemic glutamate, or another amine source as an amine donor. PRO can be obtained by the oxidative deamination of D-glufosinate to PRO (2- oxo-4-(hydroxy(methyl)phosphinoyl)butyric acid) or generated via chemical synthesis. PRO is then converted to L-glufosinate using a transaminase in the presence of an amine donor. When the amine donor donates an amine to PRO, L-glufosinate and a reaction by product are formed. Because the PRO remaining represents a yield loss of L-glufosinate, it is desirable to minimize the amount of PRO remaining in the reaction mixture. Degradation, other chemical modification, extraction, sequestration, binding, or other methods to reduce the effective concentration of the by-product, i.e., the corresponding alpha ketoacid or ketone to the chosen amine donor will shift the reaction equilibrium toward L-glufosinate, thereby reducing the amount of PRO and increasing the yield of L-glufosinate. Therefore, the methods described herein involve the conversion or elimination of the alpha ketoacid or ketone by-product to another product to shift the equilibrium towards L-glufosinate.