Purification and properties of NADPH-linked diacetyl reductase (S-acetoin forming) from Bacillus polymyxa.

Abstract

In the previous paper,1} wereported on the formation of 2,3-butanediol stereoisomers (R and meso) in Bacillus polymyxa through the action of two kinds ofenzymes. One was a previously known enzyme, /^-butanediol dehydrogenase (EC 1.1.1.4), which catalyzes the reversible reduction of acetoin to butanediol, and the other was a new enzyme, designated1* as NADPH-linked diacetyl reductase, which irreversibly reduces diacetyl to S-acetoin. This paper deals with the purification and some properties of this new enzyme. B. polymyxa IAM 1 189 was cultivated, using the same procedures as those previously mentioned, under aerobic conditions.1} Preparation of a cell-free extract and assaying of the enzyme activity (in 0.2m phosphate buffer, pH 6.0) were-performed in the same ways as previously mentioned,1>2) unless otherwise stated. Protein was estimated by the method of Bradford.3* Purification of the enzyme was conducted as follows. All procedures were performed at 0 ~4C, and 0.02 m sodium phosphate buffer (pH 7.5) was used throughout. To remove nucleic