Apps D K, Webster L C
Department of Biochemistry, University of Edinburgh, Scotland, United Kingdom.
Biochem Biophys Res Commun. 1996 Oct 23;227(3):839-45. doi: 10.1006/bbrc.1996.1594.
Organotin-flavone complexes of 3-hydroxyflavone 3,5,7-trihydroxyflavone (galangin) and 2',3,4',5,7-pentahydroxyflavone (morin) are potent inhibitors of the vacuolar H(+)-translocating ATPase from bovine adrenal chromaffin granules, with K, values around 0.3 microM. The fluorescence of the 3-hydroxyflavone complex is enhanced on binding to the purified, reconstituted V-ATPase, and tributyltin reduces this fluorescence enhancement, though not strictly competitively. Radioiodinated derivatives of galangin and morin were synthesized and their organotin complexes were crosslinked to the ATPase by ultraviolet irradiation. Subunit A (72 kDa) of the V-ATPase was labelled, and tributyltin strongly inhibited this labelling. Subunits M115 and M39 were labelled less strongly and tributyltin did not affect this labelling. We conclude that there is a specific interaction between organotin compounds and V-ATPase subunit A, in the catalytic sector of the enzyme. This approach did not detect the recently-reported interaction between dibutyltin-3-hydroxyflavone bromide and the 16 kDa 'proteolipid' subunit of the V-ATPase.
3-羟基黄酮、3,5,7-三羟基黄酮（高良姜素）和2',3,4',5,7-五羟基黄酮（桑色素）的有机锡-黄酮配合物是牛肾上腺嗜铬粒蛋白空泡H⁺转运ATP酶的有效抑制剂，其K₁值约为0.3微摩尔。3-羟基黄酮配合物与纯化、重组的V-ATP酶结合时荧光增强，三丁基锡可降低这种荧光增强，不过并非严格的竞争性抑制。合成了高良姜素和桑色素的放射性碘化衍生物，并通过紫外线照射将它们的有机锡配合物与ATP酶交联。V-ATP酶的A亚基（72 kDa）被标记，三丁基锡强烈抑制这种标记。M115和M39亚基的标记较弱，三丁基锡不影响这种标记。我们得出结论，在该酶的催化区域，有机锡化合物与V-ATP酶A亚基之间存在特异性相互作用。这种方法未检测到最近报道的二丁基锡-3-羟基黄酮溴化物与V-ATP酶16 kDa“蛋白脂质”亚基之间的相互作用。
