Nicotinamidase/pyrazinamidase (PZase). Nicotinamidase, a ubiquitous enzyme in prokaryotes, converts nicotinamide to nicotinic acid (niacin) and ammonia, which in turn can be recycled to make nicotinamide adenine dinucleotide (NAD). The same enzyme is also called pyrazinamidase, because in converts the tuberculosis drug pyrazinamide (PZA) into its active form pyrazinoic acid (POA).