Chemoenzymatic synthesis of N-linked neoglycoproteins through a chitinase-catalyzed transglycosylation.

A novel application of the Bacillus sp. chitinase for the chemoenzymatic synthesis of N-linked neoglycoproteins is described. Three chitinases with different molecular size were purified from the crude chitinase preparation. The purified chitinases were evaluated for their hydrolytic and transglycosylation activity. One chitinase with a molecular size of 100 kDa (Chi100) was identified to be the one with highest transglycosylation/hydrolysis ratio. Chi100 could effectively recognize LacNAc-oxazoline and Manalpha1,3Glcbeta1,4GlcNAc-oxazoline as the donor substrate to glycosylate Asn-linked GlcNAc, while it was unable to recognize Manbeta1,4GlcNAc and Man(3)GlcNAc-oxazolines as the donor substrates. The chitinase-catalyzed transglycosylation was successfully extended to the remodeling of ribonuclease B to afford neoglycoproteins. Although the yield needs to be optimized, the chitinase-catalyzed transglycosylation provides a potentially useful tool for the synthesis of neoglycoproteins carrying novel N-linked oligosaccharides.