Quadrangular Plates Research Articles

Studies on the Properties of Fragments of Guinea Pig γ1 and γ2 Antibodies Obtained by Papain Digestion and Mild Reduction

Summary Specifically purified guinea pig anti-hapten antibodies were digested with papain according to the method described by Porter. Immunoelectrophoretic analysis of the digested γ1 and γ2 antibodies reveals three antigenically distinct fragments. The slowest migrating component at pH 8.2 (S fragment) is yielded by both antibody types and can be shown to combine specifically with the antigen. The other two components (F1 and F2) are obtained respectively from γ1 and γ2 antibodies and are responsible for the differences in mobility of the antibody type. Upon dialysis of the papain digested antibodies, a crystalline fraction is obtained which can be identified as originating from the F1 component of the γ1-globulins. These crystals have the appearance of quadrangular plates and are barely soluble in neutral pH. Attempts to inhibit passive cutaneous anaphylaxis in guinea pig skin with the whole papain digest or with a solution of F1 crystals failed, indicating that the structure present in γ1-globulin molecules and necessary for skin fixation is lost after proteolytic action. Reduction and alkylation of guinea pig γ2-globulin in aqueous solution followed by acidification and filtration in Sephadex G-100 leads to the formation of two fractions. The first component A (75%) is heterogeneous and cannot be immunologically distinguished from the native γ2-globulin. The second, B, is contained in the papain S fragment, and contains only part of the antigenic determinants of the native γ2-globulin.