Studies on the hydrazinolysis of glycoproteins. Core structures of oligosaccharides obtained from Porcine thyroglobulin and pineapple stem bromelain.

Abstract

Hydrazinolysis of porcine thyroglobulin glycopeptides and of pineapple stem bromelain [EC 3.4.22.4] permitted the isolation of almost intact carbohydrate chains of these glycoproteins. On the basis of permethylation analyses of the released oligosaccharides after reduction with NaBH4, the core structures of Unit A-type and Unit B-type carbohydrate chains of porcine thyroglobulin were deduced to be Manalpha1 leads to 6[Manalpha1 leads to 3]Manbeta1 leads to 4GlcNAcbeta1 leads to 4[Ralpha1 leads to 6]GlcNAc leads to Asn (Unit A-type, R=H; Unit B-type, R=Fuc), and that of bromelain was found to be Manalpha1 leads to 6[R'1 leads to 2]Manbeta1 leads to 4GlcNAcbeta1 leads to 4[R1 leads to 3]GlcNAc leads to Asn (R'=Xylbeta and R=Fucalpha, or R'=Fucalpha and R=Xylbeta). From these results, it appears that the hydrazinolysis method is applicable to wide variety of glycoproteins which have an N-glycosylamine linkage between the carbohydrate and peptide moieties, regardless of the type of linkage to the most proximal N-acetylglucosamine residue which is bound to asparagine.