The Carbohydrate Composition of Immunoglobulins from Diverse Species of Vertebrates

Abstract Immunoglobulins and their respective heavy (H) and light (L) polypeptide chains from species representing the major classes of vertebrates were analyzed for their carbohydrate composition by gas chromatography of the alditol acetate derivatives of the monosaccharides released by acid hydrolysis. Mannose, galactose, glucosamine and sialic acid were present in the immunoglobulins from all the species investigated. Fucose however was absent from the immunoglobulins of two species of animals studied. Most of the carbohydrate was found associated with the H chains. The carbohydrate composition was felt to be heterogeneous in that the quantities of fucose and sialic acid found often accounted for less than one residue per H chain. Whereas species representative of the mammals and birds had mannose to galactose ratios greater than one, the ratio of these sugars to each other in the immunoglobulins from animals below the birds was on the order of one.