[Formation of higher alcohols by Saccharomyces carlsbergensis from branched-chain amino acids and their keto analogs].
A new method of chemical synthesis of alpha-ketoisocaproic acid (the keto analogue of L-leucine) is described. It has been shown that the resting cells of Saccharomyces carlsbergensis 776, in the stationary state of biomass, produce mainly higher alcohols: isobutanol from L-valine and its keto analogue; optically active amylol only from L-isoleucine and its keto analogue; isoamylol only from L-leucine and its keto analogue. "Nonspecific" formation of n-propanol from L-valine, L-isoleucine and their keto analogues, as well as that of isobutanol from L-isoleucine and its keto analogue, has been also found at pH 7.0. Formation of higher alcohols from alpha-keto acids has an acidic pH optimum while that from L-amino acids has a neutral or a weakly alkaline pH optimum. Formation of isobutanol from L-valine is an exception. The dependence of higher alcohol formation on the pH and the kinetics of their accumulation suggest that higher alcohols are produced from L-amino acids in at least three sequential reactions: transamination, decarboxylation of the keto analogue being formed, and reduction of the aldehyde; formation of higher alcohols from alpha-keto acids involves two reactions: decarboxylation and reduction. Transamination and decarboxylation are limiting steps in the process in the former case, and decarboxylation in the latter.
D000438:Alcohols / Q000096:biosynthesis*; D000597:Amino Acids, Branched-Chain / Q000378:metabolism*; D001515:Beer; D002208:Caproates / Q000138:chemical synthesis; D006863:Hydrogen-Ion Concentration; D007651:Keto Acids / Q000138:chemical synthesis / Q000378:metabolism*; D007700:Kinetics; D012440:Saccharomyces / Q000378:metabolism*
D000438:Alcohols; D000597:Amino Acids, Branched-Chain; D002208:Caproates; D007651:Keto Acids
Obrazovanie vysshikh spirtov Saccharomyces carlsbergensis iz razvetvlennykh aminokislot i ikh ketoanalogov.