Purification and characterization of monovalent cation-activated levodionereductase from Corynebacterium aquaticum M-13

(6R)-2,2,6-Trimethyl-1,4-cyclohexanedione (levodione) reductase was isolate d from a cell extract of the soil isolate Corynebacterium aquaticum M-13, T his enzyme catalyzed regio- and stereoselective reduction of levodione to ( 4R,6R)-4-hydroxy-2,2,6-trimethylcyclohexanone (actinol). The relative molec ular mass of the enzyme was estimated to be 142,000 Da by high-performance gel permeation chromatography and 36,000 Da by sodium dodecyl sulfate-polya crylamide gel electrophoresis. The enzyme required NAD(+) or NADH as a cofa ctor, and it catalyzed reversible oxidoreduction between actinol and levodi one, The enzyme was highly activated by monovalent cations, such as K+, Na, and NH4+. The NH2-terminal and partial amino acid sequences of the enzyme showed that it belongs to the short-chain alcohol dehydrogenase/reductase family. This is the first report of levodione reductase.