MONOSELENOPHOSPHATE - ITS HYDROLYSIS AND ITS ABILITY TO PHOSPHORYLATEALCOHOLS AND AMINES

The rate of hydrolysis of monoselenophosphate, the labile selenium don or compound required for the synthesis of selenium-dependent enzymes a nd seleno-tRNAs, was determined by P-31 NMR spectroscopy. The rate dep ended on the pH of the solution and was maximal at a pH similar to 7. This suggests that the dianion is the species that reacts fastest. Add ed alcohols and amines do not significantly affect the rate of hydroly sis but are phosphorylated. The entropy of activation is positive for the hydrolysis of monoselenophosphate. These data suggest a dissociati ve in nature mechanism for the hydrolysis of monoselenophosphate invol ving a monomeric metaphosphate-like transition state in the rate-deter mining step. (C) 1997 Academic Press.