title: Localization of adenosine triphosphatase activity on the chloroplast envelope in tendrils of Pisum sativum.
abstract: When samples of pea tendril tissue were incubated in the Wachstein-Meisel medium for the demonstration of adenosine triphosphatases, deposits of lead reaction product were localized between the membranes of the chloroplast envelope. The presence of Mg(2+) was necessary for adenosine triphosphatase activity, and Ca(2+) could not substitute for this requirement. Varying the pH of incubation to 5.5 or 9.4 inhibited enzyme activity, as did the addition of p-chloromercuribenzoic acid or N-ethylmaleimide. The adenosine triphosphatase was apparently inactivated or degraded when the plants were grown in the dark for 24 hours prior to incubation. The enzyme was substrate-specific for adenosine triphosphate; no reaction was obtained with adenosine diphosphate, uridine triphosphate, inosine triphosphate, p-nitrophenyl phosphate, and sodium beta-glycerophosphate. Sites of nonspecific depositions of lead are described. The adenosine triphosphatase on the chloroplast envelope may be involved in the light-induced contraction of this organelle.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002736:Chloroplasts / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D010944:Plants
chemical_list: D000251:Adenosine Triphosphatases; D008274:Magnesium; D002118:Calcium