The composition and proposed subunit structure of egg-white β-ovomucin. The isolation of an unreduced soluble ovomucin

Abstract

1. New preparations of reduced carboxymethylated β-ovomucin (S-carboxymethyl-β-ovomucin) were homogeneous by sedimentation analysis, analytical sedimentation to equilibrium in CsCl gradients, and disc electrophoresis in sodium dodecyl sulphate. 2. Degradation of S-carboxymethyl-β-ovomucin with either CNBr or trypsin indicated the presence of a subunit (approx. mol. wt. 112300). 3. Electron microscopy showed that S-carboxymethyl-β-ovomucin consisted of chains of globular units (approx. mol. wt. 103 000). IN 6M-guanidinium chloride S-carboxymethyl-β-ovomucin existed mainly as an aggregate (mol. wt. 720 000). 4. S-Carboxymethyl-β-ovomucin contained ester sulphate (4.24%, W/W) and carbohydrate (60%, W/W), which consisted of large amounts of galactose (22%, W/W), galactosamine (8.9%, W/W) and sialic acid (10.6%, W/W). 5. An unreduced soluble fibrous component (component SGH) extracted from crude ovomucin precipitate with 5M-guanidinium chloride contained β-ovomucin (approx. 70%, W/W). By using the Scheraga-Mandelkern equation the molecular weight of component SGH was calculated to be 11.5 times 10(6).