抄録
1. Highly purified laccases were obtained by ion-exchange column chromatography from Japanese lacquer tree (Rhus vernicifera) and Indo-Chinese lacquer tree (Rhus succedanea). From comparative studies of the two enzymes, it was concluded that they represent different chemical entities.
2. The two laccases have different pH optima and Michaelis constants in the oxida-tion of hydroquinone, catechol, and L-ascorbic acid. R. succedanea laccase has a much higher specific activity and heat stability than R. vernicifera laccase.
3. Both enzymes are strongly blue in color and contain nearly equal amounts of copper. Calcium and traces of magnesium can also be detected in the two enzymes. Their absorption spectra are closely similar to each other, though the positions of absorption maxima are slightly different in the two.
4. Molecular weights of both laccases calculated from their sedimentation coeffici-ents, and partial specific volumes are nearly the same. The two enzymes both contain 5 or 6 atoms of copper per molecule.
The author wishes to express his hearty gratitude to the late Prof. A. Nishimura for his interest and encouragement during this investigation, and to Prof. Y. Ogura, University of Tokyo, for his valuable advices. Thanks are also due to Mr. S. Yamamoto, the Institute for Infectious Diseases, University of Tokyo, for sedimentation measurements, to Miss K. Watatsu, the Institute of Applied Microbiology, University of Tokyo, for the operation of Spinco model H electrophoresis apparatus, and to Misses F. Shimazaki and Y. Asahi for their co-operation in this work. The author also expresses his gratitude to Saito Co. Ltd. for the kind supply of lacquer latexes.
