CHEMICAL CHARACTERIZATION OF GLYCOPEPTIDES FROM HUMAN γM-GLOBULINS

A survey of human pathological macroglobulins revealed that γM can be divided into at least two groups on the basis of carbohydrate composition. Differences between the two groups exist in the total percentage of carbohydrate (10.69 ± 1.49% for group 1, 7.71 ± 0.65% for group II) which is attributable to variation in hexose content. Glycopeptides from macroglobulins of each group were purified from pronase digests and characterized chemically. Macroglobulins from each group contain three types of oligosaccharides. Glycopeptide I for each group consisted of mannose, galactose, and NAG with a ratio of 3:2:1 for group I and a ratio of 2:1:2 for group II. Glycopeptide II consisted of mannose, galactose, and NAG (9:1:2) for group I, and mannose, fucose, galactose, and NAG (2:1:3:2) for group II. Glycopeptide III in both groups consisted of mannose, fucose, galactose, NAG, and sialic acid with a ratio of 6:2.5:2.5:5.5:2 for group I and a ratio of 5:1:1:6:1 for group II. Molecular weight estimations by gel filtration indicates that there are 10 glycopeptides I and II and 20 units of glycopeptide III per molecule of γM.