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Type: Artigo de periódico
Title: Inhibition Of Oxidative Phosphorylation By Ca2+ Or Sr2+: A Competition With Mg2+ For The Formation Of Adenine Nucleotide Complexes
Author: Fagian M.M.
da Silva L.P.
Vercesi A.E.
Abstract: Intramitochondrial Sr2+, similar to Ca2+, inhibits oxidative phosphorylation in intact rat-liver mitochondria. Both Ca2+ and Sr2+ also inhibit the hydrolytic activity of the ATPase in submitochondrial particles. Half-maximal inhibition of ATPase activity was attained at a concentration of 2.5 mM Ca2+ or 5.0 mM Sr2+ when the concentration of Mg2+ in the medium was 1.0 mM. The inhibition of ATPase activity by both cations was strongly decreased by increasing the Mg2+ concentration in the reaction medium. In addition, kinetical data and the determination of the concentration of MgATP, the substrate of the ATPase, in the presence of different concentrations of Ca2+ or Sr2+ strongly indicate that these cations inhibit ATP hydrolysis by competing with Mg2+ for the formation of MgATP. On the basis of a good agreement between these results with submitochondrial particles and the results of titrations of oxidative phosphorylation with carboxyatractyloside or oligomycin in mitochondria loaded with Sr2+ it can be concluded that intramitochondrial Ca2+ or Sr2+ inhibits oxidative phosphorylation in intact mitochondria by decreasing the availability of adenine nucleotides to both the ADP ATP carrier and the ATP synthase. © 1986.
Rights: fechado
Identifier DOI: 10.1016/0005-2728(86)90231-8
Date Issue: 1986
Appears in Collections:Unicamp - Artigos e Outros Documentos

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