Glycosylation-site-selective synthesis of N-acetyl-lactosamine repeats in bis-glycosylated human lysozyme.
We have studied the elongation of oligosaccharides containing N-acetyl-lactosamine repeats using glycosylated human lysozyme mutants as a model. We reported previously that a combination of glycosylation sites at the 49th (site IV) and 68th (site II) amino acid residues of the protein particularly stimulates the synthesis of N-acetyl-lactosamine repeats [Melcher, Grosch, Grosse and Hasilik (1998) Glycoconjugate J. 15, 987-993]. In the present study we show that it is the carbohydrate attached to site IV that is selectively affected. It contains more N-acetyl-lactosamine repeats when site II is glycosylated in the same molecule. As a corollary of the glycosylation at site II, the synthesis of a third antenna at site IV is increased. The triantennary oligosaccharides at site IV contain more N-acetyl-lactosamine repeats than the biantennary ones. Thus placing a carbohydrate at site II stimulates the branching and the elongation of the carbohydrate at the other site.
Melcher
R
R
Institut für Physiologische Chemie, Philipps-Universität Marburg, D-35033 Marburg, Germany.
Hillebrand
A
A
Bahr
U
U
Schröder
B
B
Karas
M
M
Hasilik
A
A
D000595:Amino Acid Sequence; D000606:Amino Sugars / Q000138:chemical synthesis / Q000737:chemistry*; D000818:Animals; D016466:CHO Cells; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D006020:Glycopeptides / Q000737:chemistry / Q000302:isolation & purification; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D009844:Oligosaccharides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000606:Amino Sugars; D006020:Glycopeptides; D009844:Oligosaccharides; C000458:N-acetyllactosamine; D009113:Muramidase