Dioxygen Activation by Biomimetic Iron Complexes of α-Keto Acids and α-Hydroxy Acids

2014 ◽  
pp. 39-56 ◽  
Author(s):  
Tapan Kanti Paine ◽  
Lawrence Que
Keyword(s):  
Iron Complexes ◽  
Dioxygen Activation ◽  
Hydroxy Acids ◽  
Keto Acids

Determination of α-Hydroxy Acids in Foods by TLC and Manometric Measurement

1970 ◽  
Vol 53 (3) ◽  
pp. 621-623
Author(s):  
M Trop ◽  
I M Levinger
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Exchange Resin ◽  
Anion Exchange Resin ◽  
Hydroxy Acids ◽  
Keto Acids ◽  
Alcoholic Extraction ◽  
Layer Chromatography ◽  
Manometric Measurement

Abstract An analytical method for determination of α-hydroxy and α-keto acids is developed based on separation of the acids from other components by acidic alcoholic extraction and by adsorption on and elution from an anion exchange resin, followed by thin layer chromatography. Acids are identified by eerie ammonium nitrate reagent sprayed on the chromatogram. Quantitative determination is performed by manometric measurement of gas released in reaction with that reagent.

Selective reduction of .alpha.-keto acids to .alpha.-hydroxy acids by phosphites

1977 ◽  
Vol 42 (16) ◽  
pp. 2797-2798 ◽  
Author(s):  
Takeo Saegusa ◽  
Shiro Kobayashi ◽  
Yoshiharu Kimura ◽  
Tsunenori Yokoyama
Keyword(s):  
Selective Reduction ◽  
Hydroxy Acids ◽  
Keto Acids ◽  
Alpha Hydroxy Acids

scholarly journals One-Pot Biocatalytic Preparation of Enantiopure Unusual α-Amino Acids from α-Hydroxy Acids via a Hydrogen-Borrowing Dual-Enzyme Cascade

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1470
Author(s):  
Fei Liu ◽  
Junping Zhou ◽  
Meijuan Xu ◽  
Taowei Yang ◽  
Minglong Shao ◽  
...  
Keyword(s):  
Amino Acids ◽  
Mandelic Acid ◽  
Catalytic Efficiency ◽  
Lactobacillus Brevis ◽  
Building Blocks ◽  
Hydroxy Acids ◽  
One Pot ◽  
Diverse Range ◽  
Enzyme Cascade ◽  
Keto Acids

Unusual α-amino acids (UAAs) are important fundamental building blocks and play a key role in medicinal chemistry. Here, we constructed a hydrogen-borrowing dual-enzyme cascade for efficient synthesis of UAAs from α-hydroxy acids (α-HAs). D-mandelate dehydrogenase from Lactobacillus brevis (LbMDH) was screened for the catalysis of α-HAs to α-keto acids but with low activity towards aliphatic α-HAs. Therefore, we rational engineered LbMDH to improve its activity towards aliphatic α-HAs. The substitution of residue Leu243 located in the substrate entrance channel with nonpolar amino acids like Met, Trp, and Ile significantly influenced the enzyme activity towards different α-HAs. Compared with wild type (WT), variant L243W showed 103 U/mg activity towards D-α-hydroxybutyric acid, 1.7 times of the WT’s 60.2 U/mg, while its activity towards D-mandelic acid decreased. Variant L243M showed 2.3 times activity towards D-mandelic acid compared to WT, and its half-life at 40 °C increased to 150.2 h comparing with 98.5 h of WT. By combining LbMDH with L-leucine dehydrogenase from Bacillus cereus, the synthesis of structurally diverse range of UAAs from α-HAs was constructed. We achieved 90.7% conversion for L-phenylglycine production and 66.7% conversion for L-α-aminobutyric acid production. This redox self-sufficient cascade provided high catalytic efficiency and generated pure products.

An evaluation of the substrate specificity and asymmetric synthesis potential of the cloned L-lactate dehydrogenase from Bacillusstearothermophilus

1989 ◽  
Vol 67 (6) ◽  
pp. 1065-1070 ◽  
Author(s):  
Daniel Bur ◽  
Marcel A. Luyten ◽  
Hla Wynn ◽  
Louis R. Provencher ◽  
J. Bryan Jones ◽  
...  
Keyword(s):  
Lactate Dehydrogenase ◽  
Asymmetric Synthesis ◽  
Expression Vector ◽  
Alkyl Chain ◽  
Keto Acid ◽  
Hydroxy Acids ◽  
Thermophilic Enzyme ◽  
Preparative Scale ◽  
Keto Acids ◽  
Branched Chain

The potential utility of the L-lactate dehydrogenase of Bacillusstearothermophilus (BSLDH) for stereospecific, preparative-scale reductions of α-keto acids to (S)-α-hydroxy acids of > 99% ee has been demonstrated. BSLDH is a stable, thermophilic, enzyme whose gene has been cloned into a high-expression vector to assure its plentiful supply. Its specificity for keto acid substrates possessing straight- and branched-chain alkyl, cyclopropyl, or phenyl groups has been evaluated in preparative and kinetic terms, and compared with that of the mammalian pig heart enzyme (PHLDH). The specificities of BSLDH and PHLDH are similar, with branched alkyl-chain keto acids being poor substrates for both enzymes. Keywords: enzymes in organic syntheses, lactate dehydrogenase, asymmetric synthesis.

ChemInform Abstract: Iron Complexes and Dioxygen Activation

ChemInform ◽  
2010 ◽  
Vol 41 (32) ◽  
pp. no-no
Author(s):  
Thomas Nebe ◽  
Jing-Yuan Xu ◽  
Siegfried Schindler
Keyword(s):  
Iron Complexes ◽  
Dioxygen Activation
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