title: Radiation inactivation analysis of chloroplast CF0-CF1 ATPase.
abstract: Radiation inactivation technique was employed to measure the functional size of adenosine triphosphatase of spinach chloroplasts. The functional size for acid-base-induced ATP synthesis was 450 +/- 24 kilodaltons; for phenazine methosulfate-mediated ATP synthesis, 613 +/- 33 kilodaltons; and for methanol-activated ATP hydrolysis, 280 +/- 14 kilodaltons. The difference (170 +/- 57 kilodaltons) between 450 +/- 24 and 280 +/- 14 kilodaltons is explained to be the molecular mass of proton channel (coupling factor 0) across the thylakoid membrane. Our data suggest that the stoichiometry of subunits I, II, and III of coupling factor 0 is 1:2:15. Ca2+- and Mg2+-ATPase activated by methanol, heat, and trypsin digestion have a similar functional size. However, anions such as SO3(2-) and CO3(2-) increased the molecular mass for both ATPase's (except trypsin-activated Mg2+-ATPase) by 12-30%. Soluble coupling factor 1 has a larger target size than that of membrane-bound. This is interpreted as the cold effect during irradiation.
authors.affiliation: Institute of Radiation Biology, College of Nuclear Sciences, Taiwan, Republic of China.
authors.forename: M Y
authors.initials: MY
authors.lastname: Wang
authors.forename: L F
authors.initials: LF
authors.lastname: Chien
authors.forename: R L
authors.initials: RL
authors.lastname: Pan
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000528:radiation effects*; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology*; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation; D007425:Intracellular Membranes / Q000201:enzymology; D007700:Kinetics; D010944:Plants / Q000201:enzymology
chemical_list: D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases