Occurrence, purification and properties of the staphylococcal beta-hydroxybutyrate dehydrogenase

beta-Hydroxybutyrate dehydrogenase (EC 1.1.1.30.)-an enzyme involved in degradation of polymer store material-was found in staphylococci. The enzyme was isolated from Staphylococcus xylosus NCTC D100694 cells, purified and characterized. The native enzyme is a tetramer and consists of equal subunits. Its relative molecular mass is M(r) = 140 kDa and pI = 4.7. The enzyme activity is stimulated by Mg+2 and Ca+2 ions. Staphylococcal beta-hydroxybutyrate dehydrogenase is relatively stable and active in a wide temperature range. The optimum pH for oxidation is 8.6 and for reduction 6.7. The enzyme is highly specific for D(-)stereoisomer of beta-hydroxybutyrate. Km values for beta-hydroxybutyrate and acetoacetate are 39.1 microM and 5.47 microM, respectively.