Beeley J G
Biochem J. 1976 May 1;155(2):345-51. doi: 10.1042/bj1550345.
Cleavage of the two methionine residues in the glycoprotein trypsin inhibitor ovomucoid, variant O1, with CNBr resulted in two fragments whose mol.wts. were approx. 16 600 (fragment LS) and 11 000 (fragment M). Both fragments formed precipitates with antisera to ovomucoid. Fragment LS retained 56% of the trypsin-inhibitory activity of ovomucoid, but fragment M did not inhibit. After reduction and alkylation, the molecular weight of fragment M was unchanged, but fragment LS could be resolved into two segments of peptide chain with mol.wts. of approx. 12000 (fragment L) and 4700 (fragment S). Each of these peptides contained carbohydrate. Marked heterogeneity was observed in the hexose and hexosamine contents of fragment L. This may account for much of the heterogeneity in neutral carbohydrate occurring in ovomucoid preparations. It was found that fragment M was located at the N-terminal end, fragment S was in the centre and fragment L made up the C-terminal portion of the molecule.
用溴化氰裂解糖蛋白类胰蛋白酶抑制剂卵类粘蛋白变体O1中的两个甲硫氨酸残基，产生了两个片段，其分子量约为16600（片段LS）和11000（片段M）。两个片段都能与抗卵类粘蛋白抗血清形成沉淀。片段LS保留了卵类粘蛋白56%的胰蛋白酶抑制活性，但片段M没有抑制活性。还原和烷基化后，片段M的分子量不变，但片段LS可分解为两条肽链片段，分子量约为12000（片段L）和4700（片段S）。这些肽段都含有碳水化合物。在片段L的己糖和己糖胺含量中观察到明显的异质性。这可能是卵类粘蛋白制剂中中性碳水化合物出现大量异质性的主要原因。研究发现，片段M位于分子的N末端，片段S在中间，片段L构成分子的C末端部分。
