Monosaccharides general concepts

For purposes of discussion, the biosynthetic pathway for a glycoprotein will be divided into three phases phase 1, the assembly of the polypeptide chain phase 2, the attachment of the bridge carbohydrate to specific amino acid residues of the polypeptide chain and phase 3, the addition of monosaccharides to the bridge sugar-residues. Studies in the past several years have led to a generalized concept on... 

Application of mass spectrometry to stereochemical analysis in the monosaccharide series is limited by the lack of experimental studies, by the absence of a generalizing, theoretical concept based upon modem conformational analysis, and by lack of precise knowledge of the mechanism and stereochemistry of the reactions taking place in the mass spectrometer. The only investigation in which a thorough study has been made of the effect of the stereochemical features of carbohydrates upon their mass spectra is that of Heyns and Scharmann, who measured the mass spectra of a number of permcthylated methyl pentopyranosides, namely, methyl tri-0-methyl-j8-D-ribo-(13), -arabino-(14), -xylo-(lS), and -lyxo-pyrano-sides (16), and of methyl tri-Omethyl-a-D-lyxopyranoside (17). 

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