Takikawa H, Sugiyama Y, Kaplowitz N
J Lipid Res. 1986 Sep;27(9):955-66.
Binding of bile acids and their sulfates and glucuronides by purified GSH S-transferases from rat liver was studied by 1-anilino-8-naphthalenesulfonate fluorescence inhibition, flow dialysis, and equilibrium dialysis. In addition, corticosterone and sulfobromophthalein (BSP) binding were studied by equilibrium and flow dialysis. Transferases YaYa and YaYc had comparable affinity for lithocholic (Kd approximately 0.2 microM), glycochenodeoxycholic (Kd approximately to 60 microM), and cholic acid (Kd approximately equal 60 microM), and BSP (Kd approximately 0.09 microM). YaYc had one and YaYa had two high affinity binding sites for these ligands. Transferases containing the Yb subunit had two binding sites for these bile acids, although binding affinity for lithocholic acid (Kd approximately 4 microM) was lower than that of transferases with Ya subunit, and binding affinities for the other bile acids were comparable to the Ya family. Sulfated bile acids were bound with higher affinity and glucuronidated bile acids with lower affinity by YaYa and YaYc than the respective parent bile acids. In the presence of GSH, binding of lithocholate by YaYc was unchanged and binding by YbYb' was inhibited. Conversely, GSH inhibited the binding of cholic acid by YaYc but had less effect on binding by YbYb'. Cholic acid did not inhibit the binding of lithocholic acid by YaYa.
通过1-苯胺基-8-萘磺酸盐荧光抑制法、流动透析法和平衡透析法，研究了大鼠肝脏纯化的谷胱甘肽S-转移酶对胆汁酸及其硫酸盐和葡萄糖醛酸苷的结合作用。此外，通过平衡透析法和流动透析法研究了皮质酮和磺溴酞钠（BSP）的结合作用。转移酶YaYa和YaYc对石胆酸（解离常数Kd约为0.2微摩尔）、甘氨鹅脱氧胆酸（Kd约为60微摩尔）、胆酸（Kd约等于60微摩尔）以及BSP（Kd约为0.09微摩尔）具有相当的亲和力。YaYc有一个，而YaYa有两个对这些配体的高亲和力结合位点。含有Yb亚基的转移酶对这些胆汁酸有两个结合位点，尽管对石胆酸的结合亲和力（Kd约为4微摩尔）低于含有Ya亚基的转移酶，而对其他胆汁酸的结合亲和力与Ya家族相当。YaYa和YaYc对硫酸化胆汁酸的结合亲和力较高，对葡萄糖醛酸化胆汁酸的结合亲和力低于各自的母体胆汁酸。在存在谷胱甘肽的情况下，YaYc对石胆酸盐的结合不变，而YbYb'的结合受到抑制。相反，谷胱甘肽抑制YaYc对胆酸的结合，但对YbYb'的结合影响较小。胆酸不抑制YaYa对石胆酸的结合。
