Abstract: This invention relates to human insulin analogs (tri-arg insulins) and includes two enzymatic methods for producing tri-arg insulins. These compounds can be formulated as a soluble entity up to pH 6.1 and have prolonged hypoglycemic activity. Tri-arg insulins have the basic structure of natural human insulin plus three additional arginine residues. Two of the three additional Arg residues are located in tandem at the carboxy terminus of the insulin B-chain, and the third Arg residue is located at the amino terminus of the insulin A-chain. Tri-arg insulin analogs, having certain amino acid substitutions at the B3, B10 and A21 positions, are within the instant invention.

Abstract: A dipeptidylaminopeptidase (dDAP enzyme) and a method for isolating it from the culture medium of the cellular slime mold, Dictyostelium discoideum have been presented. The isolated dDAP enzyme has a pH optimum of about 3.5 and a mass of about 225 kDA. The dDAP enzyme has an activity which is somewhat similar to both DAP-I and DAP-III from this organism. Methods for using the dDAP enzyme to remove dipeptides from the N-terminus of recombinantly produced precursor proteins or peptides are also presented.

Abstract: A method for removing dipeptides from the amino terminus of precursor polypeptides to produce a polypeptide product is presented which comprises contacting the precursor polypeptide for sufficient time to remove the dipeptide with a dipeptidylaminopeptidase (dDAP) from the slime mold, Dictyostelium descoideum, which has a mass of about 225 kilodaltons and a pH optimum of about 3.5. The precursor polypeptides may be made recombinantly and may be analogs of naturally occurring polypeptides.

Abstract: This invention relates to human insulin analogs (tri-arg insulins) and includes two enzymatic methods for producing tri-arg insulins. These compounds can be formulated as a soluble entity up to pH 6.1 and have prolonged hypoglycemic activity. Tri-arg insulins have the basic structure of natural human insulin plus three additional arginine residues. Two of the three additional Arg residues are located in tandem at the carboxy terminus of the insulin B-chain, and the third Arg residue is located at the amino terminus of the insulin A-chain. Tri-arg insulin analogs, having certain amino acid substitutions at the B3, B10 and A21 positions, are within the instant invention.