Molecular Basis of Passive Sensitization

[摘要] The effect of reduction and alkylation of Fr. III (Porter) of rabbit γ-globulin on its biologic properties was studied. The fragment was reduced in 0.1 M mercaptoethylamine in the presence or absence of urea followed by alkylation. The ability of the fragment to give reversed passive cutaneous anaphylaxis and to block passive sensitization with heterologous rabbit antibody was diminished by reduction and alkylation in saline and was nearly lost by the same treatment in 2 M urea. The fragment reduced and alkylated in saline induced an increase of permeability of guinea pig skin capillaries upon aggregation, whereas aggregates of the fragment treated in 2 M urea did not. However, the aggregates produced following reduction and alkylation in 2 M urea inactivated C′ in vitro , indicating that this treatment degrades the sites essential for tissue affinity, but does not appear to impair the sites involved in the fixation of certain C′ components. The latter sites and the antigenic determinants were degraded by complete reduction of the fragment in 6 M urea. The results suggest that the sites in 7 S γ-rabbit antibody, which are essential for tissue affinity and for C′ fixation, are not identical. The role of disulfide bonds in Fr. III on the biological properties of antibody was discussed.

[学科分类] 生物科学（综合）