Lenartowicz E
Department of Cellular Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland.
Arch Biochem Biophys. 1990 Dec;283(2):388-96. doi: 10.1016/0003-9861(90)90659-m.
This investigation presents disturbances of the mitochondrial metabolism by arsenite, a hydrophilic dithiol reagent known as an inhibitor of mitochondrial alpha-keto acid dehydrogenases. Arsenite at concentrations of 0.1-1.0 mM was shown to induce a considerable oxidation of intramitochondrial NADPH, NADH, and glutathione without decreasing the mitochondrial membrane potential. The oxidation of NAD(P)H required the presence of phosphate and was sensitive to ruthenium red, but occurred without the addition of calcium salts. Mitochondrial reactions producing alpha-ketoglutarate from glutamate and isocitrate were modulated by arsenite through various mechanisms: (i) both glutamate transaminations, with oxaloacetate and with pyruvate, were inhibited by accumulating alpha-ketoglutarate; however, at low concentrations of alpha-ketoglutarate the aspartate aminotransferase reaction was stimulated due to the increase of NAD+ content; (ii) the oxidation of isocitrate was stimulated at its low concentration only, due to the oxidation of NADPH and NADH; this oxidation was prevented by concentrations of citrate or isocitrate greater than 1 mM; (iii) the conversion of isocitrate to citrate was suppressed, presumably as a result of the decrease of Mg2+ concentration in mitochondria. Thus the depletion of mitochondrial vicinal thiol groups in hydrophilic domains disturbs the mitochondrial metabolism not only by the inhibition of alpha-keto acid dehydrogenases but also by the oxidation of NAD(P)H and, possibly, by the change in the ion concentrations.
本研究揭示了亚砷酸盐对线粒体代谢的干扰，亚砷酸盐是一种亲水性二硫醇试剂，已知是线粒体α-酮酸脱氢酶的抑制剂。浓度为0.1-1.0 mM的亚砷酸盐可诱导线粒体内NADPH、NADH和谷胱甘肽的大量氧化，而不会降低线粒体膜电位。NAD(P)H的氧化需要磷酸盐的存在，对钌红敏感，但在不添加钙盐的情况下也会发生。由谷氨酸和异柠檬酸生成α-酮戊二酸的线粒体反应受亚砷酸盐通过多种机制调节：(i) 与草酰乙酸和丙酮酸的谷氨酸转氨基反应均受到积累的α-酮戊二酸的抑制；然而，在低浓度的α-酮戊二酸时，由于NAD+含量的增加，天冬氨酸氨基转移酶反应受到刺激；(ii) 异柠檬酸的氧化仅在其低浓度时受到刺激，这是由于NADPH和NADH的氧化；当柠檬酸盐或异柠檬酸的浓度大于1 mM时，这种氧化受到抑制；(iii) 异柠檬酸向柠檬酸的转化受到抑制，推测这是线粒体中Mg2+浓度降低的结果。因此，亲水区线粒体邻位硫醇基团的消耗不仅通过抑制α-酮酸脱氢酶，还通过NAD(P)H的氧化以及可能通过离子浓度的变化来干扰线粒体代谢。
