Purity ~98% (SDS-PAGE). Human nicotinate phosphoribosyltransferase (NAPRTase) is localized in the cytoplasm and is involved in biological processes such as NAD biosynthetic and metabolic processes, nicotinamide metabolic process, nicotinate nucleotide salvage, response to oxidative stress and H2O-soluble vitamin metabolic process. It functions by catalyzing the conversion of nicotinic acid (NA) to NA mononucleotide (NaMN) and is essential for NA to increase cellular NAD levels and prevent oxidative stress of the cells. It is a crucial factor in the NAD+ biosynthesis pathway. Catalytic activity: B-nicotinate D-ribonucleotide + diphosphate = nicotinate + 5-phospho-alpha-D-ribose 1-diphosphate. Source: Recombinant protein corresponding to human NAPRTase, fused to His-tag at N-terminal, expressed in E. coli. Molecular Weight: ~58kD Biological Activity: ~0.27U/mg protein. One unit is defined as the amount of enzyme that synthesizes 1umol nicotinic acid mononucleotide (NaMN) per min.