Chinese Journal of Physiology

Chinese Journal of Physiology, 1929, Vol, IIT, No. 1, pp, 75—80.

STUDIES ON DENATURATION OF PROTEINS IX. LIBERATION OF NON-PROTEIN SUBSTANCES UPON DENATURATION AND COAGULATION OF PROTEINS

HSIEN WU anp TUNG-TOU CHEN (From the Department of Biochemistry, Peking Union Medical College, Peping) Received for publication October 81, 1928

Wu and Yen (6) showed that some non-protein substance capable of reacting with the phenol reagent of Folin and Denis was liberated when egg albumin was denatured by alkalies and, to a much smaller extent, by acids. Wu and Wu (5) showed that the liberation of nonprotein chromogenic substances also accompanied heat denaturation of egg albumin. Mastin and Rees (2) repeated our work on heat denaturation but failed to confirm our finding.

Since the liberation of non-protein substances occurs in denaturation of egg albumin by alkalies much more readily than in denaturation by acids, it seemed to us that the reaction at which the protein is denatured by heating might be an important factor and that it might offer an explanation for the discrepancy between their results and ours.

In our previous study the egg albumin was recrystallized two or three times and possibly contained some ovomucoid. This was thought to be immaterial, since it was believed that the ovomucoid would be left in the filtrate from the control as well as in that from the heated albumin solutions. Subsequent experiments have shown that it is important to use an albumin preparation which is free from ovomucoid, Ovomucoid, when present alone, is not precipitated by tungstic acid. However, when tungstic acid is added to a solution of natural egg albumin containing ovomucoid, this is adsorbed by the precipitated albumin. Denatured and flocculated albumin behaves similarly, but coagulated albumin adsorbs little or no ovomucoid in the presence of tungstic acid. Hence if the albumin preparation contains some ovomucoid, the filtrates prepared from natural, denatured, and coagulated

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