Production of a novel hyper-glycosylated human coagulation factor IX in HEK293 cells, using a Glyco-engineering Approach

Hyper-glycosylation is an approach to introduce new N-glycosylation consensus sequence(s) (Asn-Xxx-Ser/Thr three-peptide) into a protein primary amino acid sequences by site-directed mutagenesis which is followed by the attachment of a new glycan to the Asn residue located within the three-peptide sequence. Hyper-glycosylation has attracted lots of interest especially in the protein therapeutics industry. The attached glycan may improve the pharmacokinetic properties of the hyper-glycosylated priteins and increase their half-life in the bloodstream. In the current study, a new N-glycosylation site was introduced into N-terminal Gla domain of hFIX. Arg37 position of mature hFIX was targeted to be converted into Asn residue by site-directed mutagenesis using overlap extension PCR. Recombinant expression plasmids for native and mutant hFIX were constructed. The expression of the recombinant wild-type and mutant hFIX was analyzed in mammalian HEK293 cells using gradient SDS-PAGE and western blotting analysis. The results indicated in higher molecular weight for R37N mutant in compared with the native protein. The glycan attachment to R37N mutant was further confirmed by PNGase digestion and western blotting.