Patent ID: 8530417

Claim:
A Y-shaped PEGylated granulocyte colony stimulating factor (G-CSF) which is a compound of formula (I): wherein R and R′ are independently low molecular weight alkyl; m and m′ are, independently of each other, an integer which denotes the degree of polymerization; R i is H, substituted or unsubstituted C 1 -C 12 alkyl group, substituted aryl, aralkyl, or heteroalkyl; j is an integer of 1-12; F is a terminal group which is a hydroxyl group, a carboxyl group, an ester group, acyl chloride, hydrazide, maleimide, or pyridine disulfide, wherein F is capable of reacting with an amino group on G-CSF to form a covalent bond, wherein the Y-shaped PEG is conjugated with the side chain ε-amino group of a Lysine (Lys) residue in said G-CSF at position 17 of SEQ ID NO: 1.