Amino acid sequence of the VH region of a human myeloma immunoglobulin (IgG New).

The amino acid sequence of the heavy-chain variable region of the human immunoglobulin. New has been determined. Since the amino terminus of the heavy chain was blocked, the sequence of residues 1-69 was established by digesting the appropriate CNBr fragment separately with trypsin, chymotrypsin, and thermolysin and sequencing the resulting peptides. The region from residues 70 to 120 was present in another CNBr fragment which was submitted directly to automatic Edman degradation. The result of this experiment extended the sequence to residue 100. The primary structure of the remaining portion of the VH region was determined by automatic Edman degradation of a lysine-blocked tryptic peptide derived from this region which included residues 98-214. The sequence of the VH region of New corresponds most closely to VH sequences of proteins in the VH II subgroup. This primary structure makes it possible to construct a model from the high-resolution electron-density map of protein New.