In enzymology, a crotonoyl-[acyl-carrier-protein] hydratase is an enzyme that catalyzes the chemical reaction -3-hydroxybutanoyl-[acyl-carrier-protein] ⇌ {\displaystyle \rightleftharpoons } but-2-enoyl-[acyl-carrier-protein] + H2OHence, this enzyme has one substrate, [[-3-hydroxybutanoyl-[acyl-carrier-protein]]], and two products, [[but-2-enoyl-[acyl-carrier-protein]]] and H2O. Wikipedia