6 Chemical Basis of Biological Phosphoryl Transfer

摘要: Publisher Summary This chapter discusses the probable mechanisms involved in biological phosphoryl transfer reactions as disclosed by studies of model systems and their extrapolation to enzyme mediated processes. Various lines evidence have led a general acceptance dissociative monomeric metaphosphate mechanism for hydrolysis monoester monoanions derived from alcohols phenols, thiols, amines. The principal supporting data include: (a) observation P–O, P–S, or P–N bond cleavage; (b) entropies activation close zero contrast bimolecular associative solvolyzes where are usually more negative 20 eu; (c) molar product compositions (methyl phosphate : inorganic phosphate) mixed methanol–water solvent that approximate ratio methanol, water favor methyl formation, inferring presence highly reactive electrophilic species; (d) existence linear free-energy relationships between logarithmic rates dissociation constants corresponding leaving group. describes acyclic esters. Nucleophilic at phosphorus discussed chapter. Catalysis ligand loss is also