Fractionation of glycopeptides

Ogata S, Muramatsu T, Kobata A (1975) Fractionation of glycopeptides by affinity column chromatography on concanavalin A-Sepharose. J Biochem 78 687-696... 

Multiple-ion monitoring is, however, of considerable value in structural studies, but only if model compounds of known structure are available for comparison. Such an approach has been used in the study of the carbohydrate structures of glycoproteins from different tissues.50 Separation of glycopeptides obtained from various tissues was performed on columns of concanavalin A-Sepharose. Structural analysis by multiple-ion monitoring of partially methylated, alditol acetates derived from the various fractions indicated that the glycopeptides were separated according to the linkage pattern of mannose (see Fig. 1). 

Fig. 1.—Mass Fragmentograms of Partially Methylated Alditol Acetates Obtained from Rat-brain Glycopeptides. [(A) Fraction A glycopeptides, (B) fraction B glycopep-tides, and (C) fraction C glycopeptides. Peak 1, 2,3,4-tri-O-methylfucitol peak 2,...

CHARACTERISTIC GLYCOPEPTIDE FRACTION OF NATURAL MICROBUBBLE SURFACTANT... 

REVIEW OF NATURAL-PRODUCT LITERATURE AND POSSIBLE ANIMAL SOURCES OF THE GLYCOPEPTIDE FRACTION OF MICROBUBBLE SURFACTANT... 

To obtain data on the heterogeneity of the glycopeptide fraction of microbubble surfactant, comparative amino acid analyses were performed on two of the major peaks obtained from gel filtration. From the ratio of absorbances at 230 and 280 nm (ref. 265) and the elution profile shown in Fig. 5.3, it appeared that peaks I and III would differ the most in amino acid composition and, therefore, these two peaks were selected for amino acid analysis. Peak I was sufficiently large to be divided into three equal aliquots and peak III into two equal aliquots for automated analysis. Peak II, which eluted closest (Fig. 5.3) to the dominant peak I and presumably was most similar in molecular composition to this large initial peak, was analyzed separately by HPLC for carbohydrate content. 

Probable biological source of the glycopeptide fraction of microbubble surfactant... 

Table 5.2 lists the amino acid molar ratios determined for LHCP from several plant sources, and compares these results with the mean values obtained for the main glycopeptide subfraction (peak I in Table 5.1) from microbubble surfactant. It can be seen from Table 5.2 that the amino acid composition of LHCP clearly resembles that of the main glycopeptide subfraction. Specifically, in both cases nonpolar residues represent a majority and near constant fraction (i.e., 59-62%) of the amino acid composition, with the relative amounts of such residues in practically all individual cases listed following the pattern glycine > leucine, alanine, valine, proline > isoleucine, phenylalanine > methionine, tryptophan (Table 5.2). Accordingly, the glycopeptide fraction of microbubble surfactant may represent a degradation product of the light-harvesting chlorophyll a/b-protein, which is well known (ref. 373-375) to be extremely widely distributed in terrestrial, freshwater, and salt-water environments (cf. ref. 379).

Kalhnteri, P., Papadimitriou, E., and Antimisiaris, S. G., (2001), Uptake of hposomes which incorporate a glycopeptide fraction of asialofetuin by HepG2 cells, / Lipos. Res., 11,175-193. 

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