Abstract
Distribution of nicotinamidase (EC 3. 5. 1.19) was investigated in 150 kinds of samples of animals, plants and microorganisms. In general, very high activities were detected in mushrooms and marine products. Relatively high activities were found in microorganisms. The enzyme activity was not detected or very low in mammals and leaves of trees. A close relationship in the distribution was observed between this enzyme and nicotinate methyltransferase (EC 2. 1. 1. 7). Fundamental properties of nicotinamidase in the cell-free extract of several samples were compared. Namely, the optimum pH for the reaction was 6.9〜9.8 and Km values for nicotinamide at each opt mum pH were 1.2〜5.9μM. Heavy metal ions, quinolinic acid, nicotinic acid (product inhibition) were found to be potent inhibitors for partially purified nicotinamidase from "Tora-makitake" mushroom.
