In enzymology, a malonate-semialdehyde dehydrogenase () is an enzyme that catalyzes the chemical reaction 3-oxopropanoate + NAD(P)+ + H2O malonate + NAD(P)H + 2 H+ The 4 substrates of this enzyme are 3-oxopropanoate, NAD+, NADP+, and H2O, whereas its 4 products are malonate, NADH, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 3-oxopropanoate:NAD(P)+ oxidoreductase. This enzyme participates in beta-alanine metabolism. References EC 1.2.1 NADPH-dependent enzymes NADH-dependent enzymes Enzymes of unknown structure