A new isotype sequence (V kappa 27) of the variable region of kappa-light chains from a mouse hybridoma-derived anti-(streptococcal group A polysaccharide) antibody containing an additional cysteine residue. Application of the dimethylaminoazobenzene isothiocyanate technique for the isolation of peptides.

The first complete sequence of the variable region of a kappa-light chain (V kappa) from a mouse anti-(streptococcal group A polysaccharide) antibody (immunoglobulin 7S34.1) is reported. Immunoglobulin 7S34.1 was isolated from the ascitic fluid of hybridoma 7S34.1 previously cloned in vitro. A newly developed technique for the isolation of peptides by using pre-column formation of peptide derivatives with dimethylaminoazobenzene isothiocyanate also served to complete the sequence. The sequence of the variable region of the kappa-light chain of immunoglobulin 7S34.1 defines a new mouse V kappa isotype (V kappa 27) and is the first mouse immunoglobulin light-chain variable region to be shown to have an extra cysteine residue at position 48.