In reality, many enzymes have more than one substrate (A, B) and more than one product (P, Q). For example, the enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol with NAD (a biological o...In reality, many enzymes have more than one substrate (A, B) and more than one product (P, Q). For example, the enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol with NAD (a biological oxidizing agent) to form acetaldehyde and NADH.