title: p56lyn catalyzes a reversible autophosphorylation reaction and a nucleoside diphosphate kinase reaction.
abstract: The reversible autophosphorylation of the pp60c-src family tyrosine kinase, p56lyn has been characterized by a simple procedure that involves the examination of the enzyme catalyzed radioisotope exchange between ATP and ADP. The equilibrium constant of the reaction was determined to be 3.31 and corresponded to a standard free energy of hydrolysis of the phosphotyrosine bond in p56lyn of -8.08 kcal/mol. GDP was capable of substituting for ADP as phosphate acceptor so that p56lyn displayed a nucleoside diphosphate kinase activity.
authors.affiliation: Department of Medical Biochemistry, University of Calgary, Alberta, Canada.
authors.forename: C M
authors.initials: CM
authors.lastname: Litwin
authors.forename: M
authors.initials: M
authors.lastname: Gendreau
authors.forename: J H
authors.initials: JH
authors.lastname: Wang
mesh_terms: D025181:ATP Synthetase Complexes; D002384:Catalysis; D007700:Kinetics; D009097:Multienzyme Complexes / Q000378:metabolism*; D009701:Nucleoside-Diphosphate Kinase / Q000378:metabolism*; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013816:Thermodynamics; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D010770:Phosphotransferases; D011505:Protein-Tyrosine Kinases; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D025181:ATP Synthetase Complexes; D009701:Nucleoside-Diphosphate Kinase