Abstract
The effects of nicotinic acid-related compounds on the nicotinamidase activity in cultured cells of tobacco (Nicotiana tabacum XD-6) were investigated. The specific activity of the enzyme in the cells cultured in the presence of each compound at 1 mM was varied considerably. Isonicotinamide, picolinamide, 2-aminobenzamide, and benzamide enhanced the specific activity 2.5〜5.5 times. On the contrary, 3-aminobenzamide, 3-cyanopyridine, and benzoic acid (0.1 mM) supressed the specific activity to 2/3〜1/4. All these compounds were inhibitory to the growth of tobacco cells (23〜51% inhibition). Benzamide, 3-aminobenzamide, 2-aminobenzamide, and 3-cyanopyridine inhibited the enyzme reaction strongly (49〜81% inhibition) when each compound was present at 1 mM in the reaction mixture. It was also found that benzamide acted as a stabilizer for the enzyme.
