STUDIES ON NAD GLYCOHYDROLASE IN RUMEX ACETOSA TUMOUR TISSUE CULTIVATED IN VITRO

Tumour tissue of Rumex acetosa seems to possess two NAD glycohydrolases. Enzyme-I localized in the 480 × g fraction can be solubilized by 5% NaCl while Enzyme-II localized in the 5090 and 20,000 × g fraction can be solubilized by 1% triton X-100. Both enzymes have been partially purified. They show an optimum pH of 4·0 and 4·5 respectively. Both of them act on NAD and NADP but not on NMN. They also act on deamino-NAD and thionicotinamide-AD but at a reduced rate. The Km for NAD is different for the two enzymes. Both are inhibited by nicotinamide. The inhibition is competitive in case of the former whereas non-competitive in the latter. Enzyme-II requires a heat-stable and dialysable cofactor. Mg2+, Co2+ and Mo2+ are able to replace this cofactor requirement. © 1970.