2-ketoacid decarboxylases

Enzymes for Carboligation - 2-Ketoacid Decarboxylases and Hydroxynitrile Lyases 327... 

Enantioselective C-C bond formation is gaining more and more importance in bioorganic synthesis. This reaction is efficiently catalyzed by 2-ketoacid decarboxylases (E.C. 4.1.l.X) as well as by hydroxynitrile lyases (E.C. 4.1.2.X). 

The project encompassed the comparative characterization of pyruvate decarboxylase from Z. mohilis (PDC) and benzoylformate decarboxylase from P. putida (BED) as well as their optimization for bioorganic synthesis. Both enzymes require thiamine diphosphate (ThDP) and magnesium ions as cofactors. Apart from the decarboxylation of 2-ketoacids, which is the main physiological reaction of these 2-ketoacid decarboxylases, both enzymes show a carboligase site reaction leading to chiral 2-hydroxy ketones (Scheme 2.2.3.1). A well-known example is... 

The Access Code for the Microbial Production of Branched-Chain Alcohols 2-Ketoacid Decarboxylase and an Alcohol Dehydrogenase... 

THE ACCESS CODE FOR THE MICROBIAL PRODUCTION OF BRANCHED-CHAIN ALCOHOLS 2-KETOACID DECARBOXYLASE AND AN ALCOHOL DEHYDROGENASE... 

FIGURE 12.1 The Ehrlich pathway exemplified for the conversion of the branched-chain amino acids L-valine, L-isoleucine, and L-leucine to the corresponding alcohols isobntanol, 2-methyl-1-bntanol, and 3-methyl-1-butanol. Adh, alcohol dehydrogenase KE)C, 2-ketoacid decarboxylase TA, transaminase. 

FIGURE 12.2 Formation of the higher alcohols 3 -methyl-1 -butanol, isobutanol, 2-methyl-1 -butanol, and 1-butanol derived from intermediates of the branched-chain amino acid pathways. Adh, alcohol dehydrogenase KDC, 2-ketoacid decarboxylase. 

Overview of the Biochemical Properties of Relevant Enzymes with 2-Ketoacid Decarboxylase or Alcohol Dehydrogenase... 

Adh, alcohol dehydrogenase AlsS, acetohydroxyacid synthase KDC, 2-ketoacid decarboxylase YqhD, broad-range alcohol dehydrogenase TPP, thiamine pyrophosphate. 

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