Sørensen E S, Petersen T E
Department of Molecular Biology, University of Aarhus, Denmark.
J Dairy Res. 1993 May;60(2):189-97. doi: 10.1017/s0022029900027503.
Three major proteins from the proteose peptone of bovine milk were purified by Sephadex G-75 gel chromatography, Q-Sepharose ion-exchange and additional Sephadex G-75 gel chromatography in the presence of urea. From their mobility in a gradient SDS-PAGE, the proteins were found to have molecular masses of 17, 28 and 60 kDa. The N-terminal amino acid sequence of the 17 kDa protein was found to be homologous with a camel whey protein. This protein has not previously been described in bovine milk. From the SDS-PAGE results, the 28 kDa protein was judged to be the major protein of proteose peptone, contributing approximately 25% of the total. The N-terminal amino acid sequence showed no homology to any known protein sequence, but the amino acid composition indicated that the 28 kDa protein is identical with the PP3 component from the proteose peptone fraction of bovine milk, or part of it. The 60 kDa protein was found to be bovine osteopontin, a very highly phosphorylated protein with an Arg-Gly-Asp sequence which mediates cell attachment.
通过葡聚糖G-75凝胶色谱、Q-琼脂糖离子交换以及在尿素存在下的额外葡聚糖G-75凝胶色谱，从牛乳蛋白胨中纯化出了三种主要蛋白质。根据它们在梯度SDS-PAGE中的迁移率，发现这些蛋白质的分子量分别为17 kDa、28 kDa和60 kDa。发现17 kDa蛋白质的N端氨基酸序列与骆驼乳清蛋白同源。这种蛋白质此前尚未在牛乳中被描述过。根据SDS-PAGE结果，判断28 kDa蛋白质是蛋白胨的主要蛋白质，约占总量的25%。N端氨基酸序列与任何已知蛋白质序列均无同源性，但氨基酸组成表明28 kDa蛋白质与牛乳蛋白胨部分中的PP3成分相同或部分相同。发现60 kDa蛋白质是牛骨桥蛋白，一种高度磷酸化的蛋白质，具有介导细胞附着的Arg-Gly-Asp序列。
