Circular dichroism studies of M and N blood group-specific glycoproteins and glycopeptides.

CD spectra of M and N blood group glycoproteins and their NH2-terminal tryptic glycopeptides were compared. The CD spectra of glycoproteins obtained suggest the presence of a low content of alpha-helix. The M glycoprotein contained a higher percentage of a periodical structure. CD spectra of M and N tryptic glycopeptides, both sialoglycopeptides and desialylated preparates, were similar and showed positive ellipticities in the range of 210--240 m. However, the spectra of desialylated glycopeptides were red-shifted in respect to spectra of sialoglycopeptides. The CD spectra of glycopeptides suggest the presence of beta-turns.