Chernogolov A A, Schwarz D, Usanov S A
Biokhimiia. 1996 Dec;61(12):2103-15.
Bovine adrenocortical cytochrome P450scc (CYP11A1) was selectively modified with diiodofluorescein iodoacetamide (DIFIA). Only Cys264 is labeled in the P450 polypeptide chain. The modification significantly affected the cholesterol-hydroxylating activity in the reconstituted system containing NADPH, adrenodoxin reductase, adrenodoxin, and soluble or membrane-bound P450scc. The inhibitory effect correlates with decreased affinity of cytochrome P450scc to intermediate electron carrier, adrenodoxin. Cytochrome P450scc is modified in liposomes and the modified membrane-bound protein is cleaved by trypsin forming two large fragments F1 and F2 corresponding to the N- and C-terminal regions of the molecule. The data indicate that the Cys264-containing region of the cytochrome P450scc molecule is exposed to the surface of protein globule, located outside of the membrane, and can participate in protein-protein interactions.
用二碘荧光素碘乙酰胺（DIFIA）对牛肾上腺皮质细胞色素P450scc（CYP11A1）进行了选择性修饰。在P450多肽链中只有Cys264被标记。这种修饰显著影响了在含有NADPH、肾上腺皮质铁氧化还原蛋白还原酶、肾上腺皮质铁氧化还原蛋白以及可溶性或膜结合型P450scc的重组系统中的胆固醇羟化活性。抑制作用与细胞色素P450scc对中间电子载体肾上腺皮质铁氧化还原蛋白的亲和力降低相关。细胞色素P450scc在脂质体中被修饰，并且修饰后的膜结合蛋白被胰蛋白酶切割形成两个大的片段F1和F2，分别对应于分子的N端和C端区域。数据表明，细胞色素P450scc分子中含Cys264的区域暴露于位于膜外的蛋白质球体表面，并且可以参与蛋白质 - 蛋白质相互作用。
