title: Molecular aspects of activation mechanisms of CF₁.
abstract: The Ca²( +) -dependent ATPase activity of spinach chloroplast coupling factor 1 (CF₁) is activated by treatment with dithiothreitol (DDT). If excess of this reagent is eliminated by gel filtration, an Eadie-Hofstee biphasic plot is obtained. These results are consistent with the existence of two active forms of the enzyme governed by the redox state. We have observed that SDS-polyacrylamide gel electrophoresis pattern is affected by the pretreatment of the samples under those two different conditions. Spontaneous activation of the samples, due to a limited proteolytic process, has also been detected. In this case the electrophoretic pattern was also affected. The protease implied in this process could be a cystein protease co-isolated with CF₁. These observations suggest that limited proteolysis, as well as redox-induced changes, are involved in the physiological regulation of the enzyme.
authors.forename: M J
authors.initials: MJ
authors.lastname: Iraburu
authors.forename: M J
authors.initials: MJ
authors.lastname: Lopez-Zabalza
authors.forename: M
authors.initials: M
authors.lastname: Saenz
authors.forename: E
authors.initials: E
authors.lastname: Santiago
mesh_terms: D025222:Chloroplast Proton-Translocating ATPases / Q000378:metabolism*; D004229:Dithiothreitol / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D010084:Oxidation-Reduction; D011506:Proteins / Q000378:metabolism; D018724:Spinacia oleracea / Q000201:enzymology*
chemical_list: D011506:Proteins; D025222:Chloroplast Proton-Translocating ATPases; D004229:Dithiothreitol