Studies on the PEGylation of Protein at a Specific Site: Sulfhydryl-PEGylation of 97Cys-IFN-gamma.

Human recombinant interferon-gamma(IFN-gamma) is not glycosylated at site 25 Asn or 97 Asn, but its bioactivity is the same as the native one. So we suppose that mutants 25/97Cys-IFN-gamma and PEG-25/97-Cys-IFN-gamma have the same bioactivity as native. By site-directed mutagenesis, the 97Cys-IFN-gamma was obtained and modified with a new PEGylation reagent which was prepared by us with a very simple method.