BOC-CYS(NPYS)-OH (BCNP) - AN APPROPRIATE REAGENT FOR THE IDENTIFICATION OF T-CELL EPITOPES IN CYSTINE AND OR CYSTEINE-CONTAINING PROTEINS/

Some T cell epitopes become inactive when their thiols are blocked wit h various irreversible reagents (Regnier-Vigouroux, 1988; Maillere, 19 92; Maillere et al., 1993). Blocking protein and peptide thiols with B CNP (Boc-Cys(Npys)-OH) constitutes a most appropriate strategy when se arching for thiol-containing T cell epitopes. Free cysteines can thus be readily transformed into disulphide-like moieties which not only re sist undesirable oxidative reactions but which also remain susceptible to reduction by antigen presenting cells, a prerequisite for the acti vity of thiol-dependent T cell epitopes. We describe the use of this r eagent in a study of the intact disulphide-rich protein,toxin a from N aja nigricollis, and also two disulphide-containing toxin fragments.