de Bari Lidia, Valenti Daniela, Pizzuto Roberto, Paventi Gianluca, Atlante Anna, Passarella Salvatore
Istituto di Biomembrane e Bioenergetica, CNR, Via G. Amendola 165/A, 70126 Bari, Italy.
Biochem Biophys Res Commun. 2005 Oct 7;335(4):1224-30. doi: 10.1016/j.bbrc.2005.08.022.
We found that as a result of d-lactate uptake and metabolism by Jerusalem artichoke mitochondria, reducing equivalents were exported from the mitochondrial matrix to the exterior in the form of malate. The rate of malate efflux, as measured photometrically using NADP+ and malic enzyme, depended on the rate of transport across the mitochondrial membrane. It showed saturation characteristics (K(m) = 5 mM; V(max) = 9 nmol/min mg of mitochondrial protein) and was inhibited by non-penetrant compounds. We conclude that reducing equivalent export from mitochondria is due to the occurrence of a putative d-lactate/malate antiporter which differs from other mitochondrial carriers, as shown by the different inhibitor sensitivity.
我们发现，由于菊芋线粒体对d-乳酸的摄取和代谢，还原当量以苹果酸的形式从线粒体基质输出到外部。使用NADP⁺和苹果酸酶通过光度法测量的苹果酸外排速率取决于跨线粒体膜的转运速率。它表现出饱和特性（K(m)=5 mM；V(max)=9 nmol/min mg线粒体蛋白），并受到非渗透性化合物的抑制。我们得出结论，线粒体还原当量的输出是由于一种假定的d-乳酸/苹果酸反向转运体的存在，该转运体与其他线粒体载体不同，这一点从不同的抑制剂敏感性可以看出。
