Method for producing nicotinamide mononucleotide

A method for making nicotinamide mononucleotide (NMN), which method comprises at least the following steps 1) and 2):

• 1) Reacting a hypoxanthine phosphoribosyltransferase (HPT, EC 2.4.2.8) in a reaction mixture with a nucleoside monophosphate at a concentration of 0.01-500 mM and pyrophosphate at a concentration of 0.001-100 mM to produce phosphoribosyl diphosphate (PRPP);
• and
• 2) Reacting said HPT in the reaction mixture with said PRPP and nicotinamide to produce nicotinamide mononucleotide (NMN) at a concentration of 0.01-500 mM;
• wherein said nucleoside monophosphate is at least one member selected from the group consisting of adenosine monophosphate (AMP), 5′-guanylic acid (GMP), inosinic acid (IMP) and xanthosine monophosphate (XMP), said HPT is present in said reaction mixture in an amount of 0.01 U-1000 kU/L and said HPT is present in an amount of at least 90% of any enzymes present in said reaction mixture, wherein said at least 90% indicates enzyme protein weight or a unit of activity for the enzyme.