Antibody response and subunit structure of calf lens alpha crystallin

Abstract

The role of SH-containing (acidic) and SH-free (basic) subunits of calf alpha cystallin in the antibody response to the native protein was investigated. The urea solutions of SH-containing subunits were quantitatively separated from SH-free subunits on a mercurial affinity column. The separated subunits were bound to aminoethyl sulfyhydryl Sepharose in their reaggregated form (in H 2O solution) or in their monomeric form (in urea solution) and then used after removal of urea. Comparison of the relative 125I-labeled alpha crystallin antibody binding by the above immunoadsorbents directly showed that 9.8% of all anti-calf alpha crystallin antibodies were directed to antigenic determinants present on the monomeric form of SH-containing subunits and 34.4% of the antibodies were directed to antigenic determinants dependent on the reaggregation of the same subunits. By comparison, 6.4% of the antibodies reacted with antigenic determinants on the monomeric form of SH-free subunits and only 4.0% reacted with antigenic determinants dependent on reaggregation of the subunits 45.2% of antibodies formed to calf alpha crystallin were directed to antigenic determinants dependent on the cooperation of both types of subunits. The relationship between antigenic determinants expressed on monomeric forms of subunits or dependents on their reaggregation and sequential or conformational determinants is discussed.