The isolation of ovomucoid variants differing in carbohydrate composition

Three major and two minor species of ovomucoid were separated by chromatography on sulphoethyl-Sephadex. The predominant sialic acid-free species was further resolved into three fractions by DEAE-cellulose chromatography. Although all species of ovomucoid had closely similar trypsin-inhibiting activity, immunochemical properties and amino acid composition, they differ in carbohydrate composition. Wide variation was observed in the content of galactose, N-acetylglucosamine and sialic acid. Charge heterogeneity was related, in part, to variation in sialic acid content. The implications of variable carbohydrate composition for the structure and function of ovomucoid are discussed.