Evaluation of PEGylation reaction and purification of monoPEGylated recombinant human granulocyte colony stimulating factor

carried out at 1:5 molar ratio of rh-GCSF to PEG at 20-25°C. At 1 h of reaction, mainly monoPEGylated GCSF (62.4%) was formed. At 2 h of reaction, multi PEGylated GCSF (conc. 9%) was detected, where monoPEGylated GCSF constituted the most (73.2%). At 3 h of reaction, monoPEGylated (76.2%) and multi PEGylated GCSF (11.3%) were formed. Further, a process involving ion exchange and gel filtration chromatography were used to obtain pure monoPEGylated GCSF. Purified monoPEGylated GCSF was comparable to standard PEGylated rh-GCSF on NFS-60 cell line, suggesting retained biological activity of monoPEGylated GCSF. Further, the procedure is warranted for purification of other monoPEGylated proteins for therapeutic purpose.