. "Nicotinamide phosphoribosyltransferase (NamPRT) catalyzes the condensation of nicotinamide with 5- phosphoribosyl-1-pyrophosphate to yield nicotinamide D-ribonucleotide (NMN), an intermediate in the biosynthesis of NAD. It is the rate limiting component in the mammalian NAD biosynthesis pathway."^^ . . . . . . "Condensation of nicotinamide to nicotinamide D-ribonucleotide (NMN)"^^ . "2.4.2.12"^^ . . . . .