Patent ID: 8791236

Claim:
A method for selectively acylating one amino group in a peptide or protein which has two or more reactive nucleophilic functional groups, the method comprising: a) reacting in an aqueous media a peptide or protein having at least two reactive nucleophilic functional groups with an acylating agent of the general formula I wherein n is 0-4 m is 1-2 w is 4-20 R1 is a leaving group which when reacting said acylating agent with a free amine forms an amide bond between the carbonyl group attached to R1 and said amine, wherein pH in the aqueous media is between from greater than pH 8.0 to pH 14; and b) isolating the N-acylated peptide or protein, wherein an N-acylated peptide or protein is obtained comprising at least one reactive nucleophilic functional group which is not acylated or only partially acylated.