Characterization of glycerol kinase and NAD-independent glycerol-3-phosphate dehydrogenase from Pediococcus pentosaceus N5p

The pathway involved in glycerol dissimilation in Pediococcus pentosaceus N5p, a strain isolated from wine, includes glycerol kinase and NAD‐independent glycerol‐3P dehydrogenase. The properties of these enzymes were studied. Glycerol kinase activity was maximal at 28 °C and pH 7·5 in 50 mmol l−1 Tris‐HCl buffer. The end‐products of the reaction 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 dehydrogenase activity was maximal at 37 °C and pH 7·5 in 100 mmol l−1 Tris‐HCl buffer. The enzymatic activity was activated by KCN and bivalent cations as Mg2+ and Ca2+, but it was strongly inhibited by others. Dihydroxyacetone phosphate acted as competitive inhibitor while ATP and phosphenolpyruvate were non‐competitive inhibitors.