Chromatographic fractionation of phosvitin.

The presence of phosphorus-containing protein in the yolk of the hen egg was already recognized in 1900 (1). Since then, the egg yolk phosphoproteins received attention in several laboratories (cf. (2)). The first detailed study of the most highly phosphorylated fraction of yolk phosphoprotein, phosvitin, was reported by Mecham and Olcott (3) in 1949. They isolated a product containing 10% phosphorus, representing about 7% of the yolk protein and about 60 To of the yolk protein-bound phosphorus. The protein, with a minimal particle weight of about 20,000, was reported to be homogeneous in the ultracentrifuge, but heterogeneous on electrophoresis under some conditions. Results of later studies (e.g. (4-7)), mostly of a physicochemical nature, supported the suggestion (2) that phosvitin may be a fragment of a complex formed with other egg yolk components. It may also be identical with the vitellin fragments, vitellenic acid (8) or ovotyrine p (9). In the course of a study of the chemistry of phosphoproteins, we found it desirable to investigate further the nature of phosvitin and to obtain additional information bearing on the chemical structure of this protein. In this paper, we describe the fractionation of phosvitin by ion exchange chromatography and some data on the relation and differences between the chromatographic fractions.