Grunwald J, Berliner L J
Biochim Biophys Acta. 1978 Mar 14;523(1):53-8. doi: 10.1016/0005-2744(78)90008-6.
Bovine galactosyltransferase (UDPgalactose: D-glucose 4beta-galactosyltransferase, EC 2.4.1.22) was covalently coupled to Sepharose 4B by reaction at pH 5.0 with the activated mixed disulfide Sepharose-glutathione-2(5-nitropyridyl)-disulfide. The Sepharose-protein conjugate was presumably coupled via the unique highly reactive cysteine of those thiols on the bovine enzyme. The gel-bound N-acetyllactosamine and lactose synthase activity of about 0.4% was consistent with the affects of diffusion and the 90% activity reduction noted upon thiol modification of the dissolved enzyme. The residual lactose biosynthetic activity of the bound enzyme appeared possible only if the reactive thiol were physically distinct from the active site since the bulky Sepharose-glutathione group must not obscure the alpha-lactalbumin binding region.
牛半乳糖基转移酶（UDP-半乳糖：D-葡萄糖4β-半乳糖基转移酶，EC 2.4.1.22）在pH 5.0条件下与活化的混合二硫键琼脂糖-谷胱甘肽-2(5-硝基吡啶基)-二硫键反应，共价偶联到琼脂糖4B上。琼脂糖-蛋白质结合物大概是通过牛酶上那些硫醇中独特的高反应性半胱氨酸偶联的。凝胶结合的N-乙酰乳糖胺和乳糖合酶活性约为0.4%，这与扩散的影响以及溶解酶的硫醇修饰后活性降低90%是一致的。只有当反应性硫醇在物理上与活性位点不同时，结合酶的残留乳糖生物合成活性才有可能出现，因为庞大的琼脂糖-谷胱甘肽基团绝不能掩盖α-乳白蛋白结合区域。
