title: Stereochemical course of thiophosphoryl group transfer catalyzed by mitochondrial phosphoenolpyruvate carboxykinase.
abstract: Guinea pig liver mitochondrial phosphoenolpyruvate carboxykinase catalyzes the conversion of (Rp)-guanosine 5'-(3-thio[3-18O]triphosphate) and oxalacetate to (Sp)-[18O] thiophosphoenolpyruvate , GDP, and CO2 by a mechanism that involves overall inversion in the configuration of the chiral [18O]thiophosphate group. This result is most consistent with a single displacement mechanism in which the [18O]thiophosphoryl group is transferred from (Rp)-guanosine 5'-(3-thio[3-18O]triphosphate) bound at the active site directly to enolpyruvate generated at the active site by the decarboxylation of oxalacetate. In particular, this result does not indicate the involvement of a covalent thiophosphoryl-enzyme on the reaction pathway.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002849:Chromatography, Gas; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D006168:Guinea Pigs; D007700:Kinetics; D008930:Mitochondria, Liver / Q000201:enzymology*; D010071:Oxaloacetates / Q000378:metabolism; D010103:Oxygen Isotopes; D010728:Phosphoenolpyruvate / Q000031:analogs & derivatives / Q000378:metabolism; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000378:metabolism*; D011485:Protein Binding; D013873:Thionucleotides / Q000378:metabolism*
chemical_list: D010071:Oxaloacetates; D010103:Oxygen Isotopes; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D010728:Phosphoenolpyruvate; D006160:Guanosine Triphosphate; C041803:thiophosphoenolpyruvate; D010729:Phosphoenolpyruvate Carboxykinase (GTP)