Purification of the N-terminal fragment of proenkephalin from bovine adrenal medulla.

Two forms of the N-terminal fragment of proenkephalin have been purified from the bovine adrenal medulla and characterized. One of these proteins contains the sequence of Met-enkephalin and is composed of residues 1-77 of proenkephalin. The other protein does not contain Met-enkephalin and is composed of residues 1-72 of proenkephalin.