RECENT DEVELOPMENTS IN STRUCTURAL-ANALYSIS OF N-GLYCANS FROM PLANT GLYCOPROTEINS

Carbohydrate chains of glycoproteins are known to be biologically impo rtant. In plants, as in other eucaryotes, the structures of N-glycans attached to asparagine residues of the protein backbone of glycoprotei ns are highly variable and complex. Thus, the methods for carbohydrate chain analysis are far more diverse than those for protein or DNA seq uence analysis. The structural investigation of plant N-glycans is gen erally carried out in three steps: (a) cleavage of the carbohydrate ch ains from the protein moiety using specific enzymes, (b) separation of the different oligosaccharides by high-resolution chromatographies, ( c) and structural determination using physical or enzymatic methods. R ecent improvements in chromatographic fractionation as well as in stru ctural determination of complex N-glycans have allowed rapid identific ation of the N-glycosylation patterns of plant glycoproteins. These re cent developments will be of great help in the investigation of new pl ant N-glycans as well as in the N-glycosylation analysis of recombinan t glycoproteins expressed in transgenic plants.