Stereochemical course of thiophosphoryl group transfer catalyzed by mitochondrial phosphoenolpyruvate carboxykinase

• Published in: Biochemistry (Easton) Vol. 23; no. 8; pp. 1779 - 1783
• Main Authors: Sheu, Kwan Fu, Ho, Hsu Tso, Nolan, Lynn D, Markovitz, Paul, Richard, John P, Utter, Merton F, Frey, Perry A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 10.04.1984
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Binding Sites; Biological and medical sciences; Chromatography, Gas; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Guanosine 5'-O-(3-Thiotriphosphate); Guanosine Triphosphate - analogs & derivatives; Guanosine Triphosphate - metabolism; Guinea Pigs; Kinetics; liver; mitochondria; Mitochondria, Liver - enzymology; Oxaloacetates - metabolism; Oxygen Isotopes; Phosphoenolpyruvate - analogs & derivatives; Phosphoenolpyruvate - metabolism; phosphoenolpyruvate carboxykinase; Phosphoenolpyruvate Carboxykinase (GTP) - metabolism; Protein Binding; Thionucleotides - metabolism; Transferases; Vertebrata; Transfer reaction; Mammalia; Guinea pig; Enzyme; Liver; Rodentia; Reaction mechanism; Stereochemistry; Phosphoenolpyruvate carboxykinase (ATP)
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi00303a030

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.