PARTIAL SPECIFIC VOLUME MEASUREMENTS BY DIFFERENTIAL SEDIMENTATION

Abstract

The partial specific volumes of several macromolecules were determined from their sedimentation rates in aqueous and heavy water solutions with results comparable to those obtained by conventional methods. Corrections for the changes in weight due to isotopic exchange were obtained from measurements on small quantities of material with a quartz spiral balance. Measurements of the partial specific volumes of bovine plasma albumin, polyvinyl alcohol, glycine, and triglycylglycine in both aqueous and heavy water media, made with a magnetic float apparatus, indicate that isotopic exchange has no significant effect on the macromolecular volume. The sedimentation method is therefore a micro method that does not require a knowledge of the concentration of macromolecules and which is applicable to mixtures that are resolvable during sedimentation.