VOLUME AND ADIABATIC COMPRESSIBILITY OF AMINO ACIDS IN UREA-WATER MIXTURES.

Abstract

Apparent molal volumes ( phi //v) and apparent molal adiabatic compressibilities ( phi //K//S) at 25 degree C have been obtained for the following amino acids in water and in urea-water mixtures (up to 8 mol kg** minus **1 urea for phi //v and at 3 mol kg** minus **1 for phi //K//S) from measurements of density and ultrasonic velocity: glycine, L-alanine, beta -alanine, alpha -aminoisobutyric acid, L-valine, L-serine, and L-threonine. The limiting values phi //v degree and phi //K//S degree were calculated by a linear extrapolation using the least-squares method. These data were used to derive the volumes of transfer and the adiabatic compressibilities of transfer of the amino acids from water to aqueous urea solutions. Both of these transfer functions were positive.