Physiochemical characterization of proteolytic cleavage fragments of bovine colostral immunoglobulin G1 (IgG1)

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Abstract
Normal bovine colostral Ig G1 was subjected to enzymic digestion (pepsin, papain and trypsin) and the resulting fragments separated by a combination of molecular-sieve 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 (S20,w) of 5.3S, those for fragments Fab'' (peptic digestion), Fab (papain digestion) and Fab(t) (tryptic digestion) were 3.9S, 3.7S and 3.7S, respectively. The molecular weights [MW] calculated for the various fragments from the sedimentation equilibrium data were F(ab'')2, 104,000 .+-. 200; Fab'', 51,900 .+-. 340; Fab, 50,900 .+-. 230; and Fab(t)50,900 .+-. 300. Fragment Fc'' (peptic digestion) had an S20,w of 3.2S and a MW of 42,900 .+-. 650; fragment Fc (papain digestion) had an S20,w of 3.7S and a MW of 50,800 .+-. 300; fragment Fc(t) had an S20,w of 3.7S and a MW of 50,800 .+-. 450.