4 hydroxythreonine 4 phosphate dehydrogenase

In enzymology, a 4-hydroxythreonine-4-phosphate dehydrogenase (EC 1.1.1.262) is an enzyme that catalyzes the chemical reaction

4-phosphonooxy-L-threonine + NAD⁺ ⇌ (2S)-2-amino-3-oxo-4-phosphonooxybutanoate + NADH + H⁺

Thus, the two substrates of this enzyme are 4-phosphonooxy-L-threonine and NAD⁺, whereas its 3 products are (2S)-2-amino-3-oxo-4-phosphonooxybutanoate, NADH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The systematic name of this enzyme class is 4-phosphonooxy-L-threonine:NAD⁺ oxidoreductase. Other names in common use include NAD⁺-dependent threonine 4-phosphate dehydrogenase, L-threonine 4-phosphate dehydrogenase, 4-(phosphohydroxy)-L-threonine dehydrogenase, PdxA, and 4-(phosphonooxy)-L-threonine:NAD⁺ oxidoreductase. This enzyme participates in vitamin B₆ metabolism.