Purification and characterization of new aldehyde reductases from Sporobolomyces salmonicolor AKU4429

New aldehyde reductases (AR), ARII and ARIII, which reduce ethyl 4-chloro-3 -oxobutanoate (4-COBE) to ethyl 4-chloro-3-hydroxybutanoate (CHBE), with NA DPH as a cofactor, were purified from Sporobolomyces salmonicolor AKU4429. The two enzymes were different from another aldehyde reductase (ARI) which had already been purified and characterized [Yamada et al., FEMS Microbiol. Lett., 70 (1990) 45; Kataoka et al., Biochim. Biophys. Acta, 1122 (1992) 5 7]. ARII catalyzed the stereospecific reduction of 4-COBE to (S)-CHBE (92.7 % enantiomeric excess (e.e.)). In contrast, ARIII reduced 4-COBE to (R)-CHB E (38.4% e.e.). ARII was characterized further, and reduced aliphatic and a romatic aldehydes, as well as carbonyl compounds, such as camphorquinone, b ut did not accept aldose as a substrate. The enzyme is a monomer protein wi th a relative molecular mass of 34,000. Its isoelectric point is 5.0. The N H2-terminal amino acid sequence of ARII is different from that of ARI, whic h catalyzes the stereospecific reduction of 4-COBE to (R)-CHBE (100% e.e.). (C) 1999 Elsevier Science B.V. All rights reserved.