A 2,3-butanediol dehydrogenase (BDH) from Paenibacillus polymyxa ZJ-9 was purified to homogeneity via fractional ammonium sulfate precipitation, followed by two steps of anion-exchange chromatography using DEAE-Sepharose and Source 15Q, obtaining a 35-fold increase in specific activity and 34.9% yield. The molecular weights of the purified BDH subunit and holoenzyme were 44.5 and 90.0 kDa, respectively, as detected via SDS-PAGE and gel filtration chromatography. These results were significantly different from those of other reported BDHs. Substrate specificity experiments showed that the enzyme could function preferentially as a reductase rather than as a dehydrogenase, and was mainly responsible for the reduction of R-acetoin to R,R-2,3-butanediol. Gene cloning, sequencing, and expression experiments further demonstrate that this enzyme was a new type of BDH.
Keywords: 2,3-butanediol dehydrogenase; Paenibacillus polymyxa; R,R-2,3-butanediol.
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