Protein tailoring of human granulocyte colony-stimulating factor

Summary Recombinant human granulocyte-colony stimulating factor (rhG-CSF) was modified by site-directed mutagenesis and chemical modification in order to improve its pharmacological activity and its thermostability. The mutant rhG CSF which 17th cysteine was substituted with alanine was chemically modified by activated polyethylene glycol. The chemically modified mutant rhG-CSF greatly increased both its biological activityin vivo and its thermostability. This is a successful example of protein tailoring in which site-directed mutagenesis and chemical modification were used at the same time.