title: Chiral [18O]phosphorothioates. The stereochemical course of thiophosphoryl group transfer catalyzed by nucleoside phosphotransferase.
abstract: Nucleoside phosphotransferase from barley seedlings was used to catalyze the equilibration of adenosine-5'-[18O]phosphorothioate having the S configuration at phosphorus with [adenine-8-14C]adenosine to produce [adenine-8-14C]adenosine-5'-[18O]phosphorothioate and adenosine. The configuration of the chiral phosphorus in adenosine-5'-[18O]phosphorothioate which was used as the donor substrate was then compared with that of the [adenine-8-14C]adenosine-5'-[18O]phosphorothioate isolated from the reaction mixture. They were found to be the same, showing that the reaction proceeds with 99.7% retention of configuration of the [18O]phosphorothioate. This is interpreted to be indicative of the involvement of a thiophosphoryl-enzyme intermediate in the nucleoside phosphotransferase reaction. The synthesis of adenosine-5'-[18O]phosphorothioate having the R and S configurations at the phosphorus atoms is described.
mesh_terms: D000249:Adenosine Monophosphate / Q000031:analogs & derivatives*; D001467:Hordeum / Q000201:enzymology; D007700:Kinetics; D010103:Oxygen Isotopes; D010770:Phosphotransferases / Q000378:metabolism*; D010944:Plants / Q000201:enzymology; D011485:Protein Binding; D012263:Ribonucleosides; D013873:Thionucleotides
chemical_list: D010103:Oxygen Isotopes; D012263:Ribonucleosides; D013873:Thionucleotides; D000249:Adenosine Monophosphate; D010770:Phosphotransferases; C021892:nucleoside phosphotransferase