An enzyme that catalyses the removal of hydrogen from a substrate is classified as a

Explanation

Enzymes are usually named from the substrate or the reaction plus the suffix ase, so a dehydrogenase removes hydrogen, as succinate dehydrogenase does in the Krebs cycle, passing it to a coenzyme such as NAD. Hydrolases split bonds by adding water, isomerases rearrange a molecule into its isomer and ligases join two molecules together. Knowing the suffix system lets an unfamiliar enzyme name be interpreted on sight.