title: Nonequilibrium isotope exchange reveals a catalytically significant enzyme-phosphate complex in the ATP hydrolysis pathway of the AAA(+) ATPase magnesium chelatase.
abstract: Magnesium chelatase is an AAA(+) ATPase that catalyzes the first committed step in chlorophyll biosynthesis. Using nonequilibrium isotope exchange, we show that the ATP hydrolysis reaction proceeds via an enzyme-phosphate complex. Exchange from radiolabeled phosphate to ATP was not observed, offering no support for an enzyme-ADP complex.
authors.affiliation: Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
authors.forename: Nathan B P
authors.initials: NB
authors.lastname: Adams
authors.forename: James D
authors.initials: JD
authors.lastname: Reid
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D008190:Lyases / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D010710:Phosphates / Q000378:metabolism
chemical_list: D010710:Phosphates; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D008190:Lyases; C086788:magnesium chelatase