ascorbic-acid and 3-5-di-tert-butyl-4-hydroxybenzoic-acid
ascorbic-acid has been researched along with 3-5-di-tert-butyl-4-hydroxybenzoic-acid* in 1 studies
Other Studies
1 other study(ies) available for ascorbic-acid and 3-5-di-tert-butyl-4-hydroxybenzoic-acid
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Na(+)-translocating cytochrome bo terminal oxidase from Vitreoscilla: some parameters of its Na+ pumping and orientation in synthetic vesicles.
Vitreoscilla cytochrome bo ubiquinol oxidase is similar in some properties to the Escherichia coli enzyme, but unlike the latter, the Vitreoscilla oxidase functions as a primary Na+ pump. When purified Vitreoscilla cytochrome bo is incorporated into liposomes made from Vitreoscilla phospholipids and energized with a quinol substrate, it translocates Na+, not H+, across the vesicle membrane. Since protonophores CCCP (carbonyl cyanide m-chlorophenylhydrazone) and DTHB (3,5-di-tert-butyl-4-hydroxybenzaldehyde) stimulated the Na+ pumping, it is unlikely that it is a secondary effect due to the presence of Na+/H+ antiporter activity in the preparations. The efficiency of the Na+ pumping was 3.93 Na+ pumped per O2 consumed when ascorbate/TMPD was used as the substrate. The cytochrome has a K(m) and Kcat for Na+ of 2.9 mM and 277 s-1, respectively. When ferricytochrome c was entrapped within liposomes prepared from Vitreoscilla phospholipids, it was reduced by Q1H2 (ubiquinol-1) but not by ascorbate/TMPD (N,N,N',N'-tetramethyl-1,4-phenylenediamine). Although Q1H2 was oxidized by cytochrome bo in solution at a rate approximately 14 times that of the latter substrate, the rate of accumulation of Na+ within cytochrome bo vesicles driven by the membrane impermeable ascorbate/TMPD was 1.23 times that of the membrane permeable ubiquinol. These data allowed a calculation that in these synthetic proteoliposomes the cytochrome bo molecules are only 51% directed inward; a value of 61% inward-directed was estimated by measuring the ascorbate/TMPD oxidase activity of the proteoliposomes before and after disrupting them with Triton X-100. A random orientation of the E. coli cytochrome bo oxidase in proteoliposomes has also been reported. Topics: Ascorbic Acid; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Cytochrome b Group; Cytochromes; Electron Transport Complex IV; Escherichia coli Proteins; Gram-Negative Bacteria; Ionophores; Kinetics; Liposomes; Oxygen; Parabens; Permeability; Phenylenediamines; Phospholipids; Sodium; Sodium-Potassium-Exchanging ATPase; Substrate Specificity; Ubiquinone | 1996 |