The American Heritage® Dictionary of the English Language, 4th Edition
n. An enzyme that catalyzes the removal of hydrogen from a substrate and the transfer of the hydrogen to an acceptor in an oxidation-reduction reaction.
n. Any of several enzymes that catalyze the removal of hydrogen (a proton) from biological compounds.
Word Usage
"The University of Leeds researchers said the compounds work by preventing the enzyme dihydroorotate dehydrogenase, which is essential to the growth of the parasite Plasmodium falciparum, from working."