In enzymology, a 2-(hydroxymethyl)-3-(acetamidomethylene)succinate hydrolase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are 2-(hydroxymethyl)-3-(acetamidomethylene)succinate and H<sub>2</sub>O, whereas its 4 products are acetate, 2-(hydroxymethyl)-4-oxobutanoate, NH<sub>3</sub>, and CO<sub>2</sub>.
This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amides. The systematic name of this enzyme class is 2-(hydroxymethyl)-3-(acetamidomethylene)succinate amidohydrolase (deaminating, decarboxylating). Other names in common use include compound B hydrolase, alpha-hydroxymethyl-alpha'-(N-acetylaminomethylene)succinic acid, and hydrolase. This enzyme participates in vitamin B<sub>6</sub> metabolism.