Chinese Journal of Physiology

ACID- AND BASE-BINDING POWER OF PROTEINS 27

with acid or alkali than has been allowed in our experiments. (C) When the flocculated protein is coagulated, the adsorption of acid or alkali, if there is any at all, may be decreased. (D) When the coagulum is formed from the natural protein, the change from a homogenous solution to a suspension will cause unequal distribution of acid or alkali between the solution and in the suspended particles, the solution being more acid or alkaline according as the reaction of the original solution is on the acid or alkaline side of the isoelectric point. All these interpretations may be correct, but it is to be noted that while a change in the protein molecule can be the cause of coagulation, a change in the rate of combination, in the power adsorption or in the distribution of acids or alkalies are only the results of the physical change characteristic of coagulation, whatever be the cause of this phenomenon.

SUMMARY

Denaturation of protein is accompanied by a decrease of hydrogen ion concentration in acid solution or a hydroxyl ion concentration in alkaline solution. This may be interpreted as an increase of acid- and base-binding power, and supports the theory that the process underlying denaturation is one of degradation.

Coagulation has just the opposite effect. This may be explained as due to a condensation of the protein molecule with a decrease in the number of acid- and alkali-binding groups, but other explanations are

also offered.

LITERATURE

1. Cuicx, H. anp Martin, C. J. J. Physiol., 1911, 48, 1-27.

2. Cuicx, H. anp Martin, C. J. J. Physiol., 1912, 45, 61-69.

8. Harris, L, J. Proc. Roy. Soc., B, 1923, 94, 426-441,

4, Lzwis, P. S. Biochem, J., 1927, 21, 46-53.

5, Mastin, H. anp ScuryveER, S.B. Biochem. J., 1926, 20, 1177-1185,

6, PauLi, W. Colloid chemistry of the proteins, translated by P. C. L. Thorne, Philadelphia, 1922, pp. 110-120,

7. Wu, H. anp YEN, D. J. Biochern., Tokyo, 1924, 4, 845-384,

8. Wu, H. anp YEN, D. J. Biol, Chem., 1925, 64, 369-378,