“…T A. he nature of the Cand N-terminal amino acids of 7-globulin has been the subject of numerous investigations (reviewed by Eisen and Pearce, 1962;Porter and Press, 1962). In retrospect, most of these end-group determinations have failed to account satisfactorily, in terms of molar quantities, with the four-chain polypeptide structure (Fleischman et al, 1962(Fleischman et al, , 1963; Edelman and Poulik, 1961) which has emerged for IgG.1…”