Enzymes that catalyze the reversible reduction of NAD by NADPH to yield NADP and NADH. This reaction permits the utilization of the reducing properties of NADPH by the respiratory chain and in the reverse direction it allows the reduction of NADP for biosynthetic purposes.

Synonyms: EC 1.6.1.-, Energy-Linked Transhydrogenase, Transhydrogenase, Pyridine Nucleotide, Transhydrogenase, Nicotinamide Nucleotide, NAD Transhydrogenase, NADPH, NAD Transhydrogenase, Transhydrogenase, NADP, Nicotinamide Nucleotide Transhydrogenase, NADPH NAD Transhydrogenase, Energy Linked Transhydrogenase, Transhydrogenase, NADPH NAD, NADPH Transferase, Nucleotide Transhydrogenase, Nicotinamide, Transhydrogenase, Energy-Linked, Transhydrogenases, NADP, Transhydrogenase, NAD, Pyridine Nucleotide Transhydrogenase, NADP Transhydrogenases, NADP Transhydrogenase, Nucleotide Transhydrogenase, Pyridine, Transferase, NADPH