Genevieve Anne Holzapfel

MeSH headings : Catalysis; Guanosine Triphosphate / analogs & derivatives; Guanosine Triphosphate / chemistry; Guanosine Triphosphate / genetics; Guanosine Triphosphate / metabolism; Humans; Hydrolysis; Neutrons; Protein Structure, Tertiary; Proto-Oncogene Proteins p21(ras) / chemistry; Proto-Oncogene Proteins p21(ras) / genetics; Proto-Oncogene Proteins p21(ras) / metabolism

TL;DR: The neutron crystal structure of RAS bound to the GTP analogue GppNHp shows a protonated γ-phosphate at physiological pH, which counters the notion that the phosphate groups of GTP are fully deprotonated at the start of the hydrolysis reaction. (via Semantic Scholar)

MeSH headings : Acetates / metabolism; Acetates / pharmacology; Allosteric Regulation / drug effects; Allosteric Site / drug effects; Calcium Compounds / metabolism; Calcium Compounds / pharmacology; Catalytic Domain; Dithioerythritol / metabolism; Dithioerythritol / pharmacology; Dithiothreitol / metabolism; Dithiothreitol / pharmacology; Enzyme Stability / drug effects; Guanosine Triphosphate / metabolism; Guanylyl Imidodiphosphate / chemistry; Hydrolysis; Isoenzymes / chemistry; Isoenzymes / metabolism; Models, Molecular; Polyethylene Glycols / pharmacology; Protein Structure, Secondary; Small Molecule Libraries / metabolism; Small Molecule Libraries / pharmacology; Solutions; Solvents / chemistry; Solvents / pharmacology; ras Proteins / chemistry; ras Proteins / metabolism

TL;DR: It is shown with high-resolution structures that calcium acetate and either dithioerythritol (DTE) or dithiothreitol (DTT) soaked into H-Ras-GppNHp crystals in the presence of a moderate amount of poly(ethylene glycol) (PEG) can selectively shift the equilibrium to the "on" state, where the active site appears to be poised for catalysis (calcium acetate), or to what (via Semantic Scholar)

author keywords: GTPase; Raf; calcium; intrinsic hydrolysis

MeSH headings : Acetates / pharmacology; Allosteric Regulation / drug effects; Allosteric Site; Biocatalysis / drug effects; Calcium / metabolism; Calcium Compounds / pharmacology; Catalytic Domain; Crystallography, X-Ray; Enzyme Stability / drug effects; Glutamine / metabolism; Hydrogen Bonding / drug effects; Hydrolysis / drug effects; Hydroxyl Radical / metabolism; Magnesium / metabolism; Models, Molecular; Protein Structure, Tertiary; Structure-Activity Relationship; ras Proteins / chemistry; ras Proteins / metabolism

TL;DR: This structure suggests a direct catalytic role for Q61 where it interacts with a water molecule that bridges one of the γ-phosphate oxygen atoms to the hydroxyl group of Y32 to stabilize the transition state of the hydrolysis reaction. (via Semantic Scholar)