Doneen B A, Bewley T A, Li C H
Biochemistry. 1979 Oct 30;18(22):4851-60. doi: 10.1021/bi00589a013.
Methods for selective reduction of the disulfide bonds in ovine prolactin are reported. Cleavage of all three disulfide bonds abolishes biological activity and denatures the hormone. Reduction-carbamidomethylation of one or two of the disulfide bridges does not diminish the biological activities in the pigeon crop-sac and mouse mammary gland bioassays. When compared to the native hormone, monomers of these two partially reduced-carbamidomethylated derivatives also show only modest changes in properties measured by exclusion chromatography, circular dichroism, and immunological cross-reactivities. However, cleavage of cystine-4--11 and cystine-191--199, followed by carbamidomethylation, destroys the biological activity of this derivative in a teleost fish bioassay (Gillichthys urinary bladder). In contrast, reduction of cystine-4--11 actually increased the teleost potency of this derivative compared to the intact hormone. Since teleost prolactin appears to lack a homologue to the cystine-4--11 disulfide bond in the amino-terminal loop of the ovine hormone, selective reduction of this bond in ovine prolactin may produce a derivative whose properties more closely resemble the fish hormone.
本文报道了选择性还原绵羊催乳素中二硫键的方法。所有三个二硫键的断裂会消除生物活性并使该激素变性。一个或两个二硫桥的还原-氨甲酰甲基化不会降低在鸽嗉囊和小鼠乳腺生物测定中的生物活性。与天然激素相比，这两种部分还原-氨甲酰甲基化衍生物的单体在用排阻色谱、圆二色性和免疫交叉反应性测量的性质上也仅显示出适度的变化。然而，胱氨酸-4--11和胱氨酸-191--199的断裂，随后进行氨甲酰甲基化，会破坏该衍生物在硬骨鱼生物测定（吉利氏膀胱）中的生物活性。相比之下，与完整激素相比，胱氨酸-4--11的还原实际上增加了该衍生物的硬骨鱼效力。由于硬骨鱼催乳素似乎在绵羊激素的氨基末端环中缺乏与胱氨酸-4--11二硫键同源的结构，选择性还原绵羊催乳素中的该键可能会产生一种其性质更类似于鱼激素的衍生物。
