[High level expression of PNGase F in Escherichia coli and its bioactivities].

In order to obtain active recombinant PNGase F in Escherichia coli, a prokaryotic expression vector pET28a/PNGase F was constructed. Amplification of PNGase F was obtained using PCR technique employing suitable primers designed according to the PNGase F gene sequence from Flavobacterium nmeningosepticum. The expression of PNGase F gene in LB medium or M9 medium led to the formation of inclusion body and soluble protein, respectively. The refolding of the denatured inclusion body was successful by gradual dilution. Further purification of the refolded protein and soluble crude extract from M9 medium with Ni2+ -NTA argarose resulted a 90% purified PNGase F. The purified protein catalyzed the complete and intact cleavage of N-linked oligosaccharides from various glycoproteins. The efficiency of this cleavage was affected by the substrate status in the reaction system. In summary, we have developed an enzyme production system where PNGase F was over-expressed in recombinant E. coli. This system can provide more than 15 mg/L purified active PNGase F. This purified active PNGase F can be used as tools in analyzing the oligosaccharide structure.