MOLECULAR WEIGHT AND DISSOCIATION BEHAVIOR OF α- AND β-LIPOVITELLIN IN ACID SOLVENTS

Abstract

Solutions of α-lipovitellin in 1 M formic acid and 0.01 M hydrochloric acid had two sedimenting components of ca. 2.0 S and 4.6 S. Initially, acid solutions of β-lipovitellin contained only the 4.6 S component but, after about 4 days, the 2.0 S component was also present. Using freshly prepared solutions the molecular weight (M) of this 4.6 S component of β-lipovitellin was established as 3.9 × 10⁵ by both light scattering and sedimentation and diffusion measurements. This component appears, therefore, to be the associated form of β-lipovitellin of 11 S and M = 4.0 × 10⁵ in neutral solvents. The 2.0 S component must therefore be a dissociated subunit of comparable or smaller size than the subunit of 7 S and M = 2.0 × 10⁵ in alkaline solvents. Evidently both lipovitellins dissociate in acid, as they do in alkaline solvents, but the solubility behavior and irreversible changes that occur in acid precluded a quantitative study.