A Hidden Antigenic Site Localized to the Constant Region of Light Chains of Immunoglobulins

An antigenic site, which was not immunochemically demonstrable in the intact κ light polypeptide chain, was exposed by enzymatic cleavage of the κ chain into its variant half and constant half. This antigenic site located in the constant region the κ chain was detected immunochemically by several antiserums that had specificity for this site. Treatment of an intact κ chain with a dissociating agent resulted in the exposure of the hidden antigenic site, which was as readily detected in the unfolded polypeptide chain as in the isolated constant half.