胆固醇对乳酸乳球菌支链氨基酸转运系统的影响。
Effect of cholesterol on the branched-chain amino acid transport system of Streptococcus cremoris.
作者信息
Zheng T, Driessen A J, Konings W N
机构信息
Department of Microbiology, University of Groningen, Haren, The Netherlands.
出版信息
J Bacteriol. 1988 Jul;170(7):3194-8. doi: 10.1128/jb.170.7.3194-3198.1988.
The effect of cholesterol on the activity of the branched-chain amino acid transport system of Streptococcus cremoris was studied in membrane vesicles of S. cremoris fused with liposomes made of egg yolk phosphatidylcholine, soybean phosphatidylethanolamine, and various amounts of cholesterol. Cholesterol reduced both counterflow and proton motive force-driven leucine transport. Kinetic analysis of proton motive force-driven leucine uptake revealed that the Vmax decreased with an increasing cholesterol/phospholipid ratio while the Kt remained unchanged. The leucine transport activity decreased with the membrane fluidity, as determined by steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene incorporated into the fused membranes, suggesting that the membrane fluidity controls the activity of the branched-chain amino acid carrier.
在与由蛋黄磷脂酰胆碱、大豆磷脂酰乙醇胺以及不同量胆固醇制成的脂质体融合的嗜热链球菌膜囊泡中，研究了胆固醇对嗜热链球菌支链氨基酸转运系统活性的影响。胆固醇降低了逆向流动和质子动力驱动的亮氨酸转运。对质子动力驱动的亮氨酸摄取进行动力学分析表明，随着胆固醇/磷脂比例的增加，Vmax降低而Kt保持不变。如通过掺入融合膜中的1,6 - 二苯基 - 1,3,5 - 己三烯的稳态荧光偏振所测定的，亮氨酸转运活性随膜流动性降低，这表明膜流动性控制着支链氨基酸载体的活性。
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