Abstract
1. The latex of Rhus vernicifera (lacquer tree) was obtained from Ken Shii, Mao Ba and Chu Shi, China and Ibaraki, Japan, and laccase was extracted and purified from these latex samples.
2. The derivative curve of the ESR spec-trum of copper in Rhus laccase has a charac-teristic sharp signal at g=2.07 and a broad peak centered at g=2.30.
3. The oxidized forms of the enzyme preparations described above were found to contain different percentages (90-50%) of Cu++ as estimated by the ESR and the cuproine methods. The extinction of the enzyme at 615 mμ was proportional to the content of total copper, while the enzymatic activity was proportional to the amount of Cu++ in the enzyme.
4. From these results, the evidence ob-tained previously by magnetic susceptibility measurements on Ken Shii-laccase was con-firmed, and results suggested that the cuprous ion, which constitutes 10-50% of the copper in the oxidized form of laccase, is not involved in the active center of the enzyme.
The authors greatly appreciate the kindness of the Saito Co., Osaka, for their supply of crude latex used in this investigation. They are indebted also to Japan Electron Optics Laboratory Co., Tokyo, for the ESR measurements.
