文章基本信息

标题：Surface localization of sites of reduction of nitroxide spin-labeled molecules in mitochondria
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作者：A T Quintanilha ; L Packer
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1977
卷号：74
期号：2
页码：570-574
DOI：10.1073/pnas.74.2.570
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The relative rates of reduction of several spin-labeled molecules that partition differently across the hy-drophobic-interface of inner membranes from rat liver mitochondria were investigated. Spin labels localized either deep in the hydrophobic region or in the aqueous phase are only slowly reduced; however a spin-labeled analogue of the cationic detergent cetyltrimethylammonium bromide that partitions at the interface is rapidly reduced by coupled electron transport. Chemical studies on the reduction and oxidation of the spin label show that loss of signal is due to reduction and not destruction of the label. No evidence was found for flip-flop of the label in submitochondrial preparations. Spin reduction of respiring mitochondria, mitoplasts, or inverted submitochondrial preparations is inhibited by rotenone but is relatively insensitive to antimycin A and KCN. Because the midpoint potentials of the spin labels were found to be similar to that of ubiquinone, it is concluded that reducing equivalents of mitochondrial electron transport from this region of the chain are channeled to either membrane interface.