Chávez E, Peña A, Zazueta C, Ramírez J, García N, Carrillo R
Departamento de Bioquímica Instituto Nacional de Cardiología, Ignacio Chávez, UNAM, Mexico, DF, Mexico.
J Bioenerg Biomembr. 2000 Apr;32(2):193-8. doi: 10.1023/a:1005516115189.
Mitochondrial permeability transition occurs through a Ca2+-dependent opening of a transmembrane pore, whose identity has been attributed to that of the adenine nucleotide translocase (ANT). In this work, we induced permeability transition by adding 0.5 microM carboxyatractyloside. The process was evaluated analyzing Ca2+ efflux, a drop in transmembrane electric gradient, and swelling. We found that the amphiphyllic cations octylguanidine and octylamine, at the concentration of 100 microM, inhibited, almost completely, nonspecific membrane permeability. Hexylguanidine, hexylamine, as well as guanidine chloride and hydroxylamine failed to do so. The inhibition was reversed after the addition of 40 mM Li+, Na+ K+, Rb+, or Cs+; K+ was the most effective. We propose that the positive charge of the amines interact with negative charges of membrane proteins, more likely the ADP/ATP carrier, while the alkyl chain penetrates into the hydrophobic milieu of the inner membrane, fixing the reagent.
线粒体通透性转换通过跨膜孔的钙离子依赖性开放而发生，该跨膜孔的身份被认为是腺嘌呤核苷酸转位酶（ANT）。在这项工作中，我们通过添加0.5微摩尔的羧基苍术苷来诱导通透性转换。通过分析钙离子外流、跨膜电梯度下降和肿胀来评估该过程。我们发现，浓度为100微摩尔的两亲性阳离子辛基胍和辛基胺几乎完全抑制了非特异性膜通透性。己基胍、己基胺以及氯化胍和羟胺则没有这种作用。在添加40毫摩尔的锂离子、钠离子、钾离子、铷离子或铯离子后，抑制作用被逆转；钾离子最为有效。我们提出，胺类的正电荷与膜蛋白的负电荷相互作用，很可能是与ADP/ATP载体相互作用，而烷基链则穿透内膜的疏水环境，固定该试剂。
