Stereochemical control on yeast reduction of .alpha.-keto esters. Reduction by immobilized bakers' yeast in hexane

Microbial Preparation of Chiral Alcohols: Stereoselective Reduction of Carbonyl Compounds using Two Genera of the Streptosporangiaceae Family - Streptosporangium and Nonomuraea

“…(%) = [(R-S)/(R+S)] x 100, where R and S are the respective peak areas according to GLC analysis. The absolute configurations of the -hydroxy esters (2a-h) and aromatic -hydroxy amide (2i) were identified by comparing their retention times as determined by GLC analysis with those of authentic samples (Nakamura et al, 1998;Mitsuhashi and Yamamoto, 2005).…”

“…Ethyl pyruvate (Figure 1, 1a (2i), and -hydroxy esters (2b-f) were prepared according to procedures described in the literature (Nakamura et al, 1998;Mitsuhashi and Yamamoto, 2005). All other chemicals used in this study were of analytical grade and commercially available.…”

Stereoselective Reduction of Carbonyl Compounds Using the Cell-Free Extract of the Earthworm,Lumbricus rubellus, as a Novel Source of Biocatalyst

“…For example, bakers' yeast (Saccharomyces cerevisiae) has often been used for the reduction of keto esters to obtain optically active hydroxyl esters. 4,5) Furthermore, other microorganisms (such as yeast, 6) aerobic bacteria, [7][8][9] and microalgae 10) ) or plant cultured cells 3) that can catalyze the stereoselective reduction of keto esters are also used for the preparation of chiral hydroxyl esters. As described above, the biotransformation using microorganisms or plant cells as biocatalysts has been widely investigated, however, the bioconversion using other organisms, such as invertebrates, has rarely been reported.…”

“…Other -keto esters and -hydroxy esters were synthesized according to standard methods. 4) The earthworms (L. rubellus, brand name ''Rintarou'') were purchased from Nobeoka Asahi Senni (Miyazaki, Japan; E-mail: nakamura.yr@om.asahi-kasei.co.jp). NADPH and NADH were obtained from Kohjin, Tokyo, Japan.…”

“…The absolute configuration of the isomer was determined by comparing its retention time with those of authentic samples prepared according to standard methods. 4) The cell-free extract of the earthworm was tested for its reducing ability toward various carbonyl compounds. The results of the reducing activities in the presence of NAD(P)H are summarized in Table 1.…”