The Behavior of the Prolamins in Mixed Solvents. Ii

A quantitative description of the solubility behavior of gliadin in mixtures of water with certain alcohols has been given recently by Dill and Alsberg (1).There now has been completed a similar study of zein, a companion protein.In addition to mixtures of water with methyl, with ethyl, and with n-propyl alcohol, mixtures of water with tertiary butyl alcohol have been employed as solvents.Also, observation has been made of the behavior of gliadin in mixtures of water with tertiary butyl alcohol.The zein preparation used is the one of Professor Osborne used by Cohn, Berggren, and Hendry (2).The gliadin was prepared by the author according to the method of Dill and Alsberg (1).Their experimental procedure for determining turbidity temperatures was followed without modification.It had been found that there is no well defined upper limit to the solubility of gliadin in certain alcohol-water mixtures and within certain temperature limits.The results of two preliminary experiments on zein, detailed in Table I, indicate that this prolamin may be characterized similarly.These results, together with a former similar experiment with gliadin, are illustrated in Fig. 1.In the indicated mixtures of alcohol and water, the solubility of gliadin and of zein increased rapidly with the temperature until a concentration of about 3 gm.per 100 gm. of solution was reached.At this point no further increase in temperature was required to dissolve a great deal more protein.That this curious phenomenon is not explained by supersaturation was proved by observing both the appearance of turbidity on