Structural studies of two ovalbumin glycopeptides in relation to the endo-beta-N-acetylglucosaminidase specificity.
Heterogeneities of the two ovalbumin glycopeptides, (Man)5(GlcNAc)2Asn and (Man)6(GlcNAc)2Asn, were revealed by borate paper electrophoresis of oligosaccharide alcohols obtained from the glycopeptides by endo-beta-N-acetylglucosaminidase H digestion and NaB3H4 reduction. The structures of the major components of the oligosaccharides were determined by the combination of methylation analysis, acetolysis, and alpha-mannosidase digestion. Based on the results, the whole structures of the major components of (Man)5(GlcNAc)2Asn and (Man)6(GlcNAc)2Asn were elucidated as Manalpha1 leads to 6[Manalpha1 leads to 3]-Manalpha1 leads to 6[Manalpha1 leads to 3[Manbeta1 leads to 4GlcNAcbeta1 leads to 4GlcNAc leads to Asn and Manalpha1 leads to 6[Manalpha1 leads to 3]Manalpha1 leads to 6[Manalpha1 leads to 2Manalpha1 leads to 3]Manbeta1 leads to 4GlcNAcbeta1 leads to GlcNAc leads to Asn, respectively. Since endo-beta-N-acetylglucosamini dase D hydrolyzes (Man)5(GlcNAc)2Asn but not (Man)6(GlcNAc)2Asn, the presence of the unsubstituted alpha-mannosyl residue linked at the C-3 position of the terminal mannose of Manbeta1 leads to 4GlcNAcbeta1 leads to 4 GlcNAcAsn core must be essential for the action of the enzyme.
D000117:Acetylglucosamine / Q000032:analysis; D000118:Acetylglucosaminidase / Q000378:metabolism*; D000818:Animals; D001216:Asparagine / Q000032:analysis; D002645:Chickens; D008401:Gas Chromatography-Mass Spectrometry; D006020:Glycopeptides / Q000032:analysis*; D006596:Hexosaminidases / Q000378:metabolism*; D007700:Kinetics; D008358:Mannose / Q000032:analysis; D008892:Milk / Q000032:analysis; D010047:Ovalbumin / Q000032:analysis*; D013296:Streptococcus pneumoniae / Q000201:enzymology; D013305:Streptomyces griseus / Q000201:enzymology
D006020:Glycopeptides; D001216:Asparagine; D010047:Ovalbumin; D006596:Hexosaminidases; D000118:Acetylglucosaminidase; D008358:Mannose; D000117:Acetylglucosamine