Surface charge modifications do not affect the hydrolytic activity of membrane-bound pyrophosphatase of Rhodospirillum rubrum.
The surface charge of the membrane of chromatophores of Rhodospirillum rubrum was modified by two methods: fusion of liposomes with the membrane of the chromatophore by changing the pH and by incubating chromatophores in the presence of cationic or anionic detergents. The hydrolytic activity of membrane-bound pyrophosphatase, on surface charge modified chromatophores, did not change the Km of the enzyme for its substrate (Mg-PPi2-) nor the activation effect of free Mg2+ on the hydrolytic activity. This membrane enzyme is not regulated by surface charge.
Sosa
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Departamento de Bioenergética, Universidad Nacional Autónoma de México, México, D.F.
Celis
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D020130:Bacterial Chromatophores / Q000201:enzymology; D004789:Enzyme Activation; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008081:Liposomes / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D017616:Magnesium Compounds / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011755:Pyrophosphatases / Q000737:chemistry / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000201:enzymology* / Q000254:growth & development; D013379:Substrate Specificity; D013499:Surface Properties
D005456:Fluorescent Dyes; D008081:Liposomes; D017616:Magnesium Compounds; D010710:Phosphates; C030781:magnesium phosphate; D011755:Pyrophosphatases; D008274:Magnesium