Patent ID: 8212002

Claim:
A process of making a polylpeptide or a pharmaceutically acceptable salt thereof, wherein the polypeptide comprises L-alanine, L-tyrosine, L-glutamate, and L-lysine, and the process comprises reacting a L-lysine protected polypeptide, which comprises L-alanine, L-tyrosine, L-glutamate, and L-lysine that is protected with a first protecting group, with a tetraalkylammonium hydroxide in water to remove the first protecting group, and wherein the L-lysin protected polypeptide is prepared by a process comprising: a) polymerizing a mixture of the N-carboxyanhydrides of L-alanine, L-tyrosine, L-glutamate that is protected with a second protecting group, and L-lysine that is protected with the first protecting group n a solvent to obtain a protected polypeptide; and b) reacting the protected polypeptide in step a) with hydrobromic acid in acetic acid to remove the second protecting group and to obtain the L-lysine protected polypeptide.