Human granulocyte-colony stimulating factor isoforms
Disclosed is a novel physiologically active protein, which is a human granulocyte colony stimulating factor isoform, constructed in order to increase the in vivo lifetime of human granulocyte colony sedtimulating factor. The human granulocyte colony stimulating factor isoform comprises a polypeptide and polyethylene glycol (PEG) bound thereto as a non-protein polymer. A specific site of the polypeptide is selected so that polyethylene can be bound to the site while not adversely affecting the activity of the protein. The amino acid of the site is modified with cysteine and polyethylene glycol is bound to the modified site. A pharmaceutical composition comprising the isoforms, genes encoding the isoforms, and a primer for modifying the amino acid sequence are also disclosed.
1. A granulocyte colony stimulating factor isoform, which includes at least one amino acid added before Thr of N-terminal or after Pro of C-terminal in human granulocyte colony stimulating factor (SEQ ID NO:1) wherein at least one of the added amino acids is cysteine, and wherein a branched polyethylene glycol is bound to a cysteine of the isoform protein.
2. The granulocyte colony stimulating factor isoform according to claim 1 , wherein the polyethylene glycol has a molecular weight of 20 kDa˜40 kDa.
3. A granulocyte colony stimulating factor isoform, wherein 133-threonine of the granulocyte colony stimulating factor (SEQ ID NO:1) is substituted with cysteine, and wherein a branched polyethylene glycol is bound to a cysteine of the isoform protein.
4. The granulocyte colony stimulating factor isoform according to claim 3 , wherein the polyethylene glycol has a molecular weight of 20 kDa˜40 kDa.