Prasad R, Ebner K E
J Biol Chem. 1980 Jun 25;255(12):5834-7.
alpha-Lactalbumin was purified from the milk of Wistar rats and was compared to that obtained from Fisher 344 rats. alpha-Lactalbumin isolated from the Wistar rat exists as two forms which differ in their sialic acid content, as the desialyated forms migrate to one identical position on polyacrylamide gels. These two charge forms are identical with the charge Forms II and III previously characterized from Fisher rat alpha-lactalbumin. No evidence was found to verify previous reports that one form of the Wistar rat alpha-lactalbumin had a higher molecular weight than the other form. Indeed, the molecular weights and the amino acid compositions of the two forms of Wistar rat alpha-lactalbumin are identical. In addition, the partial amino acid sequence at the NH2-terminal end and the amino acid composition of the COOH-terminal cyanogen bromide peptide of the two forms are identical. The results in this study contradict those reported previously and show that rat alpha-lactalbumin exists as a single molecular weight species.
从Wistar大鼠的乳汁中纯化出α-乳白蛋白，并将其与从Fisher 344大鼠获得的α-乳白蛋白进行比较。从Wistar大鼠分离出的α-乳白蛋白以两种形式存在，它们的唾液酸含量不同，因为去唾液酸化形式在聚丙烯酰胺凝胶上迁移到相同位置。这两种电荷形式与先前从Fisher大鼠α-乳白蛋白中鉴定出的电荷形式II和III相同。没有证据证实先前的报道，即Wistar大鼠α-乳白蛋白的一种形式比另一种形式具有更高的分子量。实际上，Wistar大鼠α-乳白蛋白两种形式的分子量和氨基酸组成是相同的。此外，两种形式的NH2末端的部分氨基酸序列和COOH末端溴化氰肽的氨基酸组成是相同的。本研究结果与先前报道的结果相矛盾，表明大鼠α-乳白蛋白以单一分子量形式存在。
