Strömqvist M, Hernell O, Hansson L, Lindgren K, Skytt A, Lundberg L, Lidmer A S, Bläckberg L
Astra Hässle AB, Tvistevägen 48, Umeâ, S-907 36, Sweden.
Arch Biochem Biophys. 1997 Nov 1;347(1):30-6. doi: 10.1006/abbi.1997.0307.
Analysis of milk samples from a number of lactating women revealed molecular variants of bile salt-stimulated lipase (BSSL) of both lower and higher molecular mass than that commonly occurring. In contrast to previous observations, we report on individuals having only a variant of lower mass, both one of lower and one of common mass, or both one of lower and one of higher mass of the lipase. From two individuals we purified the lower molecular mass BSSL variant and characterized it. The amount of lipase in the milk of these two individuals was considerably less than average (mean of 10 women with BSSL of the most common molecular mass). The BSSL variant of lower mass showed the same bile salt activation, pH dependency, temperature stability as those most commonly occurring. We could localize the difference in mass to the large O-glycosylated repeat sequence close to the C-terminus of the protein. With respect to all characteristics studied, the BSSL variant of higher mass was also similar to that most commonly ocurring. Again, the difference in mass could be localized to the repeat region of the protein. Hence, it appears as if the repeat region, normally carrying 16 repeats of 11 amino acids each, varies in size between individuals.
对多位哺乳期女性的乳汁样本分析发现，胆汁盐刺激脂肪酶（BSSL）存在分子量低于和高于常见分子量的分子变体。与之前的观察结果不同，我们报告了仅具有低分子量变体、同时具有低分子量和常见分子量变体或同时具有低分子量和高分子量变体的个体。我们从两名个体中纯化了低分子量的BSSL变体并对其进行了表征。这两名个体乳汁中的脂肪酶含量明显低于平均水平（10名具有最常见分子量BSSL的女性的平均值）。低分子量的BSSL变体表现出与最常见变体相同的胆汁盐激活、pH依赖性和温度稳定性。我们能够将分子量差异定位到蛋白质C末端附近的大O-糖基化重复序列。就所有研究的特征而言，高分子量的BSSL变体也与最常见的变体相似。同样，分子量差异也可以定位到蛋白质的重复区域。因此，看起来通常每个含有16个11个氨基酸重复序列的重复区域在个体之间大小不同。
