title: A stereochemical investigation of the hydrolysis of cyclic AMP and the (Sp)-and (Rp)-diastereoisomers of adenosine cyclic 3':5'-phosphorothioate by bovine heart and baker's-yeast cyclic AMP phosphodiesterases.
abstract: Bovine heart cyclic AMP phosphodiesterase, which has a requirement for Mg2+, hydrolyses cyclic AMP with inversion of configuration at the phosphorus atom, but only the (Sp)-diastereoisomer of adenosine cyclic 3':5'-phosphorothioate is hydrolysed by this enzyme. By contrast, the low-affinity yeast cyclic AMP phosphodiesterase, which contains tightly bound Zn2+, hydrolyses both the (Sp)- and the (Rp)-diastereoisomers of adenosine cyclic 3':5'-phosphorothioate, the (Rp)-diastereoisomer being the preferred substrate under V max. conditions. Both of the diastereoisomers of adenosine cyclic 3':5'-phosphorothioate, as well as cyclic AMP, are hydrolysed with inversion of configuration at the phosphorus atom by the yeast enzyme. It is proposed that, with both enzymes, the bivalent metal ion co-ordinates with the phosphate residue of the substrate, and that hydrolysis is catalysed by a direct "in-line' mechanism.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D008968:Molecular Conformation; D009206:Myocardium / Q000201:enzymology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013237:Stereoisomerism; D013873:Thionucleotides / Q000378:metabolism*
chemical_list: D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases