Final answer:
Dehydrogenases are enzymes that transfer hydrogen atoms from a substrate to acceptor molecules, typically coenzymes like NAD or NADP, playing a crucial role in cellular metabolism.
Step-by-step explanation:
Dehydrogenases are a subgroup of oxidoreductases that participate in oxidation-reduction reactions. They play a crucial role in metabolism by transferring hydrogen atoms from substrates to acceptor molecules. These hydrogen acceptors are typically coenzymes such as NAD (Nicotinamide Adenine Dinucleotide) or NADP (Nicotinamide Adenine Dinucleotide Phosphate), FAD (Flavin Adenine Dinucleotide), and FMN (Flavin Mononucleotide).
When a substrate is the donor, dehydrogenases remove a hydrogen ion (proton) along with two electrons, which is essentially a hydride ion (H⁻), and transfer it to an acceptor. In aerobic conditions, dehydrogenases like pyruvate dehydrogenase can transfer the extracted hydrogen directly to oxygen to form water. In anaerobic conditions, the hydrogen can be transferred to other substrates or substances such as the cytochromes mentioned. This process is integral to energy production in cells, particularly in pathways such as glycolysis and the citric acid cycle.