1. It was found by means of filter-paper electrophoresis that at least three kinds of peroxidases are present in the crude extract of turnip roots used in the present experiment.
2. These three peroxidases were isolated separately and highly purified, and designated as “turnip peroxidases A
1, A
2 and D” Turnip peroxidase D was obtained in a crystalline form (needle shape).
3. Physicochemical properties of these preparations were examined and thier homogeneity was confirmed. All these peroxidases obtained had the same prosthetic group as that of horseradish peroxidase, and their molecular weights or sedimentation coefficients were found almost same each other. They exhibited, however, different behaviour in electrophoresis.
4. The P. Z. of turnip peroxidase D was comparable to that of horseradish peroxidase II or that of Japanese-radish peroxidase
a, while the P. Z. of turnip perosidases A
1 and A
2, in spite of the highest R. Z. of these enzymes, were considerably lower than that of turnip peroxidase D.
5. Besides the above peroxidases JP-A
1 A
2 and D), another peroxidase having the absorption spectrum similar to that of horseradish peroxidase I was obtained. However, this peroxidase was considered to be a substance produced during the course of isolation.
The author wishes to express his sincere thanks to Prof. B. Tamamushi, Dr. S. Nagakura and Y. Ogura of the University of Tokyo for their invaluable advice and encouragement throughout this work. He is indebted to Prof. N. Ui of Gunma University for the sedimentation measurements and to Dr. H. Nakamura of the Institute for Infectious Diseases, the University of Tokyo, for boundary electrophoresis measurements. Thanks are also due to Dr. I. Yamazaki of Tohoku University and Dr. Y. Morita of Kyoto University for their valuable suggestions for the preparation procedures. This study was aided in part by a Grant-in-Aid for the Scientific Research from the Ministry of Education given to the Research Group on the “Mechanism of Enzyme Action”.
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