Macromolecular components of the vitelline membrane of hen's egg. III. Physicochemical properties of glycoprotein II.

A glycoprotein fraction (GP-II) has been isolated from the vitelline membrane of hen's egg and its physicochemical properties clarified. GP-II is composed of polypeptide (92%), neutral sugar (4%), hexosamine (3.3%), and sialic acid (0.6%). The constituent neutral sugars of this glycoprotein are fucose, mannose, and galactose, in a molar ratio of 2:6:5. An interesting feature of the amino acid composition of GP-II is the high proportion of proline. GP-II exists in an aggregated form and is hydrophobic in nature. Upon velocity sedimentation in 0.5% SDS solution, it showed a hypersharp boundary with an apparent sedimentation coefficient of 5.6 S. Reduction of GP-II, however, gave a single component of 3.6 S which seems to be a subunit of GP-II.