Diacetyl (Acetoin) Reductase from Aerobacter aerogenes Evidence for Multiple Forms of the Enzyme

A homogeneous preparation of diacetyl (acetoin) reductase from Aerobacter aerogenes has been shown to consist of several isoelectric species. The native enzyme consists of at least 12 species, all possessing enzymatic activity. No differences in the band patterns were observed when curd extract, purified enzyme, purified enzyme in the presence of NAD, and reactivated enzyme from urea treatment, were subjected to isoelectric focusing in polyacrylamide gels. Electrofocusing of the monomers in urea gels gave at least 5 bands. The isoelectric points for the bands were in the range of 5.8 to 6.8.