GLYCEROL KINASE - SUBSTRATE-SPECIFICITY

Glycerol kinase (E.C. 2.7.1.30, ATP: glycerol-3-phosphotransferase) catalyzes the phosphorylation of 28 nitrogen, sulfur, and alkyl-substituted analogues of glycerol. A survey of 66 analogues has defined qualitatively the structural characteristics necessary for acceptability as substrate by this enzyme. This survey was conducted using an assay based on 31P NMR spectroscopy which detected products produced even by slow reactions. These studies indicate that glycerol kinase accepts a range of substituents in place of one terminal hydroxyl group (that which is not phosphorylated), and that the hydrogen atom at C-2 can be replaced by a methyl group. Replacement of the second terminal hydroxyl group (that which is normally phosphorylated) by other nucleophilic centers usually results in loss of activity. Glycerol kinase is a useful catalyst for the synthesis of chiral organic substances, especially starting materials for the preparation of phospholipids and analogues. Comparisons of kinetic constants for enzymes from four microorganisms (Candida mycoderma, Saccharomyces cerevisiae, Escherichia coli, and Bacillus stearothermophilus) indicate little variation among them. All phosphorylated products have stereochemistry analogous to that of sn-glycerol-3-phosphate.