Fang W D, Mukkur T K
Biochem J. 1976 Apr 1;155(1):25-30. doi: 10.1042/bj1550025.
Normal bovine colostral immunoglobulin G1 was subjected to enzymic digestion (pepsin, papain and trypsin) and the resulting fragments separated by a combination of molecularsieve and phosphocellulose chromatography. Fragments F(ab')2 derived from peptic digestion, fragment Fab from papain digestion and fragment Fab(t) from tryptic digestion showed complete antigenic identity with each other. Although fragment F(ab')2 (peptic digestion) had a sedimentation coefficient (S2o,w) of 5.3S, those for fragments Fab' (peptic digestion), Fab (papain digestion) and Fab(t) (tryptic digestion) were found to be 3.9S, 3.7S and 3.7S respectively. The mol.wts. calculated for the various fragments from the sedimentation equilibrium data were: F(ab')2, 104000 +/-200; Fab', 51900+/-340; Fab, 50900+/-230; Fab(t) 50900+/-300. Fragment Fc' (peptic digestion) had an S20,w of 3.2S and a mol. wt. of 42900+/-650; fragment Fc (papain digestion) had an SI0,w of 3.7S and a mol.wt. of 50800+/-300; fragment Fc(t) had an S20,w of 3.7S and a mol.wt. of 50800+/-300; fragment Fc(t) had an S20,w of 3.7S and a mol.wt. of 50800+/-450.
将正常牛初乳免疫球蛋白G1进行酶消化（胃蛋白酶、木瓜蛋白酶和胰蛋白酶），并通过分子筛和磷酸纤维素色谱法相结合的方法分离得到的片段。胃蛋白酶消化产生的F(ab')2片段、木瓜蛋白酶消化产生的Fab片段和胰蛋白酶消化产生的Fab(t)片段彼此具有完全相同的抗原性。虽然F(ab')2片段（胃蛋白酶消化）的沉降系数（S20,w）为5.3S，但发现胃蛋白酶消化产生的Fab'片段、木瓜蛋白酶消化产生的Fab片段和胰蛋白酶消化产生的Fab(t)片段的沉降系数分别为3.9S、3.7S和3.7S。根据沉降平衡数据计算出的各种片段的分子量分别为：F(ab')2为104000±200；Fab'为51900±340；Fab为50900±230；Fab(t)为50900±300。胃蛋白酶消化产生的Fc'片段的S20,w为3.2S，分子量为42900±650；木瓜蛋白酶消化产生的Fc片段的S10,w为3.7S，分子量为50800±300；Fc(t)片段的S20,w为3.7S，分子量为50800±300；Fc(t)片段的S20,w为3.7S，分子量为50800±450。
