A purification method for improving the process yield and quality of recombinant human granulocyte colony‐stimulating factor expressed in <i>Escherichia coli</i> and its characterization

A purification method employing a process-control strategy was developed for improving the yield of rhG-CSF (recombinant human granulocyte colony-stimulating factor). A purity of >/=99% with an overall yield of 2.18 g/l was achieved in the present study. Analysis of the product during purification indicated that detergents removed 72% of LPS (lipopolysaccharides) and 98% of HCPs (host cell proteins) without removing nucleic acid. Cysteine concentration was a key parameter in protein refolding. The bed height and HETP (height equivalent theoretical plates) value in the SEC (size-exclusion chromatography) column was evaluated and its impact on the resolution was studied. Formulation during SEC was found to be crucial for increasing the product yields with saving of time and process costs. The yield obtained in the present study is nearly four times higher than that reported in the literature. The product obtained was found to be acceptable for toxicological studies.