Lack of posttranslational modifications in E. coli
|
Glycosylation |
Expression without the glycosylation (only if the biological activity is not impaired) |
IL-2 [3], IFN-β-1b [4] |
Mutation of residues on the surface to create more soluble protein |
EPO [5] |
Mutation of glycosylation sites to cysteines to allow subsequent glycosylation in vitro
|
EPO [6] |
Proteolytic maturation |
Expression in two separate strains or cleavage of the precursor in vitro
|
insulin [7] |
Disulfide bridge formation |
Expression in the periplasmic space |
hGH [8], proinsulin [9] |
Protein stability |
Decreasing number of free cysteine residues by mutation to alanine |
IL-2 [10], IFN-β-1b [11] |
Deletion of the hydrophobic region |
KGF [12] |
Modulation of protein activity |
Design of the rapid-acting or long-acting protein version |
insulin [13-17] |
Enhanced activity by improved affinity to the target molecule |
DNaseI [18] |
Design of protein consisting of a consensus sequence |
IFN-α-con [19, 20] |