Characterization of a variable fragment of a human immunoglobulin lambda chain obtained by peptic cleavage in urea.

The digestion of a human dimeric lambda Bence Jones protein with pepsin in 8 M urea without prior reduction and alkylation produced a fragment of molecular weight 11,000, designated as upV lambda, corresponding to almost the entire variable region of an immunoglobulin light chain. The C-terminal amino acid residue of fragment upV lambda was shown to correspond to leucine at position 104 of the immunoglobulin lambda light chain. Fragment upV lambda was isolated in the yield of 30% by ion exchange chromatography after gel filtration. When another lambda Bence Jones protein was treated in the same way, similar results were obtained.