Bound water and phase equilibria in protein systems : egg albumin and muscle

Abstract

This work is largely an extension of that already carried out on gelatin (Moran, 1926, 1932; Lloyd and Moran, 1934; and Hardy, 1926). These papers discussed (a) the crystal pattern and nature of the ice phase in frozen gels; (b) the amounts and nature of the water in equilibrium with unit mass of gelatin at different temperatures or activities of water. 1-Egg Albumin The egg albumin was prepared by Hopkins’s method, slightly modified as described by Adair and Robinson (1930). It was found that thorough washing with the solution prepared by adding 60 cc M sodium acetate solution and 40 cc of M acetate acid to 100 cc of saturated ammonium sulphate solution gave a sufficiently pure albumin since its water relations (as described later) were identical with those of an albumin recrystallized three times after this washing. The solution of albumin was dialysed under slight pressure at 0° C for several weeks until, in the final test, a 24-hour dialysate from approximately 60 cc of albumin solution, when concentrated to 1-2 cc, gave no reaction for sulphate. Several samples of concentrated albumin solution were prepared. The concentration (grams albumin per 100 grams of solution) varied from 20 to 33% with a ∆ con­sistent at about 0·025°; thephas measured by the glass electrode was 4·8. The conductivity per 1% egg albumin never exceeded 2 x 10-5mhos.