title: Stereochemistry of the hydrolysis of adenosine 5'-thiophosphate catalyzed by venom 5'-nucleotidase.
abstract: The stereochemical problem involving a pro-pro-prochiral phosphorus center, the hydrolysis of adenosine 5'-monophosphate to adenosine and inorganic phosphate catalyzed by the venom 5'-nucleotidase, has been studied by use of chiral [16O, 17O, 18O]thiophosphates (Psi). (Rp)- and (Sp)-[alpha-18O1]Adenosine 5'-thiophosphates (AMPS) were synthesized by a combined chemical and biochemical procedure. Hydrolysis of (Rp)- and (Sp)-[alpha-18O1]AMPS in H217O by 5'-nucleotidase gave two enantiomers of chiral Psi of unknown configuration. A 31P NMR method based on the combination of the quadrupolar effect of 17O [Tsai, M.-D. (1979) Biochemistry 18, 1468-1472] and the 18O isotope shift [Cohn, M., & Hu. A. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 200-203] has been developed to analyze the configuration of chiral Pso. The results indicate that hydrolysis of (Rp)- and (Sp)-[alpha-18O1]AMPS in H217O gave (R)- and (S)- [16O, 17O, 18O]Psi, respectively. Therefore the hydrolysis of AMPS catalyze by the venom 5'-nucleotidase must proceed with inversion of configuration at phosphorus, which suggests that the reaction is most likely an "in line" single displacement without involving a phosphoryl-enzyme intermediate and without pseudorotation.
mesh_terms: D015720:5'-Nucleotidase; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives*; D003435:Crotalid Venoms / Q000494:pharmacology; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009708:Nucleotidases / Q000494:pharmacology*; D010758:Phosphorus; D013873:Thionucleotides
chemical_list: D003435:Crotalid Venoms; D013873:Thionucleotides; C014308:adenosine 5'-phosphorothioate; D010758:Phosphorus; D000249:Adenosine Monophosphate; D009708:Nucleotidases; D015720:5'-Nucleotidase