Atlante A, Gagliardi S, Passarella S
Centro di Studio sui Mitocondri e Metabolismo Energetico, CNR, Bari, Italy.
Biochem Biophys Res Commun. 1998 Feb 24;243(3):711-8. doi: 10.1006/bbrc.1998.8147.
In order to gain some insight into the fate of fumarate synthesised in the cytosol in the purine nucleotide cycle and in amino acid catabolism, the capability of both rat kidney mitochondria and acidotic rat kidney mitochondria to take up either externally synthesised, via adenylsuccinate lyase, or added fumarate in exchange with intramitochondrial malate or aspartate was tested by means of both spectrophotometric and isotopic techniques. The appearance of either malate or aspartate caused by the presence of fumarate was revealed outside normal and acidotic mitochondria by using specific substrate detecting systems. Consistently, externally added fumarate was found to cause efflux of either [14C]-malate or [14C]-aspartate from loaded mitochondria. The occurrence in rat kidney mitochondria of two separate translocators, i.e., fumarate/malate and fumarate/aspartate carriers, is shown in the light of saturation kinetics and the different inhibitor sensitivity. The fumarate/aspartate antiporters found in normal and acidotic mitochondria appear to differ from each other.
为了深入了解嘌呤核苷酸循环和氨基酸分解代谢过程中在胞质溶胶中合成的富马酸的去向，通过分光光度法和同位素技术测试了大鼠肾线粒体和酸中毒大鼠肾线粒体摄取通过腺苷酸琥珀酸裂解酶体外合成的富马酸或添加的富马酸以与线粒体内苹果酸或天冬氨酸交换的能力。利用特定的底物检测系统，在正常和酸中毒线粒体外部揭示了由富马酸的存在引起的苹果酸或天冬氨酸的出现。一致地，发现外部添加的富马酸会导致负载线粒体中[14C] - 苹果酸或[14C] - 天冬氨酸的流出。根据饱和动力学和不同的抑制剂敏感性，表明大鼠肾线粒体中存在两种独立的转运体，即富马酸/苹果酸和富马酸/天冬氨酸载体。在正常和酸中毒线粒体中发现的富马酸/天冬氨酸反向转运体似乎彼此不同。
