Recent data on the structure of the carbohydrate moiety of glycoproteins. Metabolic and biological implications

摘要: The author reviews the information acquired in last four years on structure of isoglycans (branched glycans) N-glycosidically linked to asparagine. Developments structural methodology conjugated carbohydrates are analysed with reference following procedures: sugar determination, chemical (partial acid hydrolysis, acetolysis, hydrazinolysis—nitrous deamination), and enzymatic (exoand endoglycosidases) cleavage polysaccharide chains, methylation. Several structures glycans described. It appears that all possess common pentasccharidic core mannotriosido-di-N-acetylchitobiose which either neuraminyl (or fucosyl)-N-acetyllactosamine or oligomannoside residues. is proposed term these glycan structures, respectively, N-acetyllactosaminic type oligomannosidic type. demonstrates a good agreement recent data concerning, one hand, biosynthesis pathological catabolism glycoproteins and, other biological role carbohydrate moieties considered as cell recognition signals. INTRODUCTION Four ago, lecture given at Fifth International Symposium Carbohydrate Chemistry, I reviewed the' present state knowledge concerning moiety glycoproteins. conclusion was about century after discovery compounds, no known, except those some linear (n-glycans). Our ignorance due, partly, microheterogeneity partly lack precise methods for investigation branched (iso-glycans). review82 concluded by emphasizing fact 'an enormous methodological work 431