抄録
1. The inhibitory action of urethane upon the reaction catalyzed by the glucose dehydrogenase from Aspergillus oryzae was investiaged from kinetic point of view.
2. The inhibition caused by urethane is reversible. The narcotic combines with the enzyme without competing with hydrogen-acceptor and substrate. It is, therefore, assumed that urethane combines not only with free enzyme molecule but also with enzyme-acceptor-complex as well as with enzyme-acceptor-substrate-complex, and indeed, with the same dissocidation constant in all cases. Experimental evidence was adduced which indicates that the dissociation constant mentioned above remains the same (0.25 mole, /lit.) for different hydrogen acceptors and different substrates. It is also independent of temperature in the range from 0° to 30°.
3. Based on the data obtained, thermodynamical quantities of the reaction in which urethane combines with the enzyme molecule was estimated.
The author wishes to thank Prof. Hiroshi Tamiya for his valuable suggestions and encouragement in this work.
