CHARACTERIZATION OF GLYCEROL KINASE AND NBD-INDEPENDENT GLYCEROL-3-PHOSPHATE DEHYDROGENASE FROM PEDIOCOCCUS-PENTOSACEUS M5P

The pathway involved in glycerol dissimilation in Pediococcus pentosac eus N5p, a strain isolated from wine, includes glycerol kinase and NAD -independent glycerol-3P dehydrogenase. The properties of these enzyme s were studied. Glycerol kinase activity was maximal at 28 degrees C a nd pH 7.5 in 50 mmol l(-1) Tris-HCL buffer. The end-products of the re action acted as competitive inhibitors while fructose-1,6-diphosphate was a non-competitive inhibitor. Mg2+ was required for optimal enzyme activity. The Km values for both substrates were 0.11 and 0.37 mmol l( -1) for glycerol and ATP, respectively. NAD-independent glycerol-3P de hydrogenase activity was maximal at 37 degrees C and pH 7.5 in 100 mmo l l(-1) Tris-HCl buffer. The enzymatic activity was activated by KCN a nd bivalent cations as Mg2+ and Ca2+, but it was strongly inhibited by others. Dihydroxyacetone phosphate acted as competitive inhibitor whi le ATP and phosphenolpyruvate were non-competitive inhibitors.