Phosphonate dehydrogenase, originally isolated from the Gram-negative bacterium Pseudomonas stutzeri (strain WM88), was the first protein known to catalyze redox chemistry on inorganic phosphorus compounds. Phosphonate dehydrogenase catalyzes the oxidation of phosphonate to phosphate with the concurrent reduction of NAD+ to NADH. Due to the strong exergonic nature of the reaction, phosphonate dehydrogenase has gained a particularly high interest for use as a cofactor regeneration enzyme.