Antigenicity of Polypeptides (PolyαAmino Acids): Calcium-Dependent and Independent Antibodies

[摘要] It has been shown that sheep antisera against negatively charged synthetic polymers of amino acids such as poly (L-glu60-L-ala30-L-tyr10)n of high glutamic acid content contain two populations of antibodies one of which requires calcium (“Ca++ dependent”) for reaction to occur. The Ca++-dependent antibodies are directed against immunogenic determinants created by the reaction of Ca++ with glutamyl residues which changes the conformation of the polymer and thereby creates the new determinants. The reaction of the specific polymer with this antibody is maximal at 0.008 M Ca++. Dissociation of the polymer-Ca++-antibody complex can be accomplished by removal of Ca++ with EDTA, citrate or oxalate or by washing the antigen-antibody precipitate with phosphate-buffered saline. Dilution of the antiserum in non-Ca++-containing diluents, which in effect lowers the Ca++ concentration, reduces precipitation of the antibody. This loss can be reversed by addition of Ca++ to the diluting buffer. The amounts of these two populations of antibodies vary from animal to animal within any species. No Ca++-dependent antibody was found with the polymers of slight negative or neutral charge or against several protein antigens. Peptide maps (finger prints) of these two kinds of purified antibody (both 7S IgG) revealed no significant differences.

[学科分类] 生物科学（综合）