Abstract
Hydrolysis with papain of chicken IgG (C-IgG), pheasant IgG (P-IgG) and quail IgG (Q-IgG) produced fragments with sedimentation coefficients of 3.5S. Approximately 40% to 50% of the IgG was converted to dialyzable peptides.
Digestion of C-IgG pseudoglobulin preparations with 1% pepsin at pH 4.5 for 18 hr, in the absence of a reducing agent, produced Fab′ (3.4S) fragments. Digestion of C-IgG with pepsin at pH 5.0 produced a small amount of 5.4S fragments, Fab′ and undigested IgG. Chicken pseudoglobulin and euglobulin IgG appeared to have different susceptibilities to digestion with pepsin. Digestion of P-IgG with 1% pepsin, at pH 4.5, resulted in 5.4S fragments and undigested IgG, whereas digestion with 2% pepsin yielded mainly 5.4S and a small amount of Fab′. The F(ab')2 fragment contained no Fc determinants, but compared to papain-produced Fab it had additional antigenic determinants. Digestion of Q-IgG with 1% pepsin, pH 4.5, produced about 60% Fab′ and 40% 5.4S fragments. With respect to the kinds of fragments formed, Q-IgG was intermediate between C-IgG and P-IgG. Large amounts of dialyzable peptides were formed from the three immunoglobulins by peptic digestion.
Footnotes
This investigation was supported in part by United States Public Health Service Research Grant AI 05660-05 and Training Grant AI 0243-05 from the National Institute of Allergy and Infectious Diseases.
