Commercial neuraminidase preparations isolated from Clostridium perfringens were found to be contaminated with endoglycosidase and protease activities. The preparations release oligosaccharide fragment(s) with G1cNAc at the reducing end, from the intact ovalbumin. The enzymes also converted Asn-(GlcNAc)2(Man)5 isolated from ovalbumin into Asn-GlcNAc and an oligosaccharide with G1cNAc at the reducing end. Similar results were obtained when Taka-amylase A and its glycopeptide were used as substrates. These results identify the endoglycosidase activity as endo-β-N-acetylglucosaminidase. Furthermore, the commercial neuraminidase preparations contain a protease activity which hydrolyzes Azocoll, hemoglobin, casein, ovalbumin, human serum albumin, and α1-acid glycoprotein.
Biochemical and biophysical research communications 65(2), pp.683-691