THE MECHANISM OF GUANOSINE NUCLEOTIDE HYDROLYSIS BY P21 C-HA-RAS - THE STEREOCHEMICAL COURSE OF THE GTPASE REACTION

  • 15 April 1989
    • journal article
    • research article
    • Vol. 264  (11) , 6188-6190
Abstract
The use of guanosine 5''-O-(.gamma.-thio)triphosphate as a substrate for p21 c-Ha-ras was established. By using chirally labeled [.gamma.-17O,18O]guanosine 5''-O-(.gamma.-thio)triphosphate, the stereochemical course of the GTPase reaction was determined. The analysis shows that the hydrolysis occurs with inversion at the .gamma.-phosphorus. This shows that the most likely mechanism is a single step, in line transfer, without a phosphoenzyme or other phosphorylated intermediate.