Figure 1: Alcohol Metabolism. The enzymes alcohol dehydrogenase (ADH), cytochrome P450 (CYP450) and catalase, all contribute to the oxidative metabolism of ethanol. ADH in the cell converts alcohol to acetaldehyde, which is then metabolized mainly by aldehyde dehydrogenase (ALDH) in the mitochondria to form acetate and NADH + H+.