87172-81-4Relevant articles and documents
Purification and characterization of two alpha-keto ester reductases from Streptomyces thermocyaneoviolaceus IFO 14271.
Yamaguchi, Hitomi,Nakajima, Nobuyoshi,Ishihara, Kohji
, p. 588 - 597 (2002)
Two NADPH-dependent alpha-keto ester reductases (Streptomyces thermocyaneoviolaceus keto ester reductase, STKER-II and -III) were purified from S. thermocyaneoviolaceus IFO 14271, one of thermophilic actinomycetes. The molecular masses of native STKER-II
Stereocontrolled reduction of α- and β-keto esters with micro green algae, Chlorella strains
Ishihara, Kohji,Yamaguchi, Hitomi,Adachi, Noriko,Hamada, Hiroki,Nakajima, Nobuyoshi
, p. 2099 - 2103 (2007/10/03)
The stereocontrolled reduction of α- and β-keto esters using micro green algae was accomplished by a combination of the cultivation method and the introduction of an additive. The reduction of ethyl pyruvate and ethyl benzoylformate by the photoautotrophically cultivated Chlorella sorokiniana gave the corresponding alcohol in high e.e. (>99% e.e. (S) and >99% e.e. (R), respectively). In the presence of glucose as an additive, the reduction of ethyl 3-methyl-2-oxobutanoate by the heterotrophically cultivated C. sorokiniana afforded the corresponding (R)-alcohol. On the other hand, the reduction in the presence of ethyl propionate gave the (S)-alcohol. Ethyl 2-methyl-3-oxobutanoate was reduced in the presence of glycerol by the photoautotrophically cultivated C. sorokiniana or the heterotrophically cultivated C. sorokiniana to the corresponding syn-(2R,3S)-hydroxy ester with high diastereo- and enantiomeric excess (e.e.). Some additives altered the stereochemical course in the reduction of α- and β-keto esters.
Mechanistic study for stereochemical control of microbial reduction of α-keto esters in an organic solvent
Nakamura, Kaoru,Kondo, Shin-Ichi,Nakajima, Nobuyoshi,Ohno, Atsuyoshi
, p. 687 - 694 (2007/10/02)
To elucidate the mechanism for stereochemical control of yeast reduction of α-keto esters in organic media, seven enzymes responsible for the reduction have been isolated from bakers' yeast and kinetic parameters for enzymatic reductions have been measured. In yeast reduction of ethyl 3-methyl-2-oxobutanoate (1f), enantiomeric excess in the produced (R)-hydroxy ester increases when an organic solvent is used as the reaction medium in place of water. Difference in K(m) of the enzymes contributes largely to the stereochemistry of reduction by whole yeast cell. Four enzymes contribute to catalytic reduction of 1f. K(m) of the (R)-producing enzyme has been found to be the lowest among those of four enzymes. Stereochemical course of the reduction shifts toward the (R)-product by lowering the substrate concentrations, because the (R)-producing enzyme is most active among the enzymes under diluted conditions. In yeast reduction of ethyl 2-oxohexanoate (1d), the corresponding (S)-hydroxy ester is obtained in water, whereas the antipode is given in benzene. Five enzymes participate to the reduction of 1d and the (R)-producing enzymes have smaller K(m)s than those of the (S)-producing enzymes. When the reaction is run in benzene, however, the produced α-hydroxy ester does not undergo further decomposition. The inhibition of enzymatic decomposition in an organic solvent is also accounted for by low concentration of α-hydroxy ester in aqueous phase surrounding the bakers' yeast.
