title: A phosphoryl transfer intermediate in the GTPase reaction of Ras in complex with its GTPase-activating protein.
abstract: The hydrolysis of nucleoside triphosphates by enzymes is used as a regulation mechanism in key biological processes. Here, the GTP hydrolysis of the protein complex of Ras with its GTPase-activating protein is monitored at atomic resolution in a noncrystalline state by time-resolved FTIR spectroscopy. At 900 ms, after the attack of water at the gamma-phosphate, there appears a H2PO4- intermediate that is shown to be hydrogen-bonded in an eclipsed conformation to the beta-phosphate of GDP. The H2PO4- intermediate is in a position where it can either reform GTP or be released from the protein in 7 s in the rate-limiting step of the GTPase reaction. We propose that such an intermediate also occurs in other GTPases and ATPases.
authors.affiliation: Lehrstuhl für Biophysik and Institut für Physiologische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Kötting
authors.forename: Marco
authors.initials: M
authors.lastname: Blessenohl
authors.forename: Yan
authors.initials: Y
authors.lastname: Suveyzdis
authors.forename: Roger S
authors.initials: RS
authors.lastname: Goody
authors.forename: Alfred
authors.initials: A
authors.lastname: Wittinghofer
authors.forename: Klaus
authors.initials: K
authors.lastname: Gerwert
mesh_terms: D001665:Binding Sites; D004789:Enzyme Activation; D006160:Guanosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011522:Protons; D017550:Spectroscopy, Fourier Transform Infrared; D020703:ras GTPase-Activating Proteins / Q000737:chemistry* / Q000378:metabolism; D018631:ras Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010710:Phosphates; D011522:Protons; D020703:ras GTPase-Activating Proteins; D006160:Guanosine Triphosphate; D018631:ras Proteins