Biochemistry

Taking away hydrogen atoms from the substrate, nicotinamide passes from the oxidized form to the reduced form, and from the hydrogen acceptor becomes its donor. Substrate + NADP2 + H ‘ Substrate-H, + NAD NAD (oxidizing form) HO' y-OOHH 2 R NADP2 (reduced form) Flavin enzymes. The next acceptor of hydrogen atoms is a group of flavin enzymes that transfer hydrogen (electrons and protons) from the reduced form of NAD (NADH 2 ) to cytochromes. ¥\avm dehydrogenases include complex enzymes, the non-protein part of which are flavin adenine dinucleotide (FAD). In contrast to nicotinamide adenine dinucleotide, FAD contains, instead of nicotinic acid amide, a vitamin B 2 residue . It is combined with ribose derivatives (ribitol), two phosphoric acid residues, ribose and adenine. FMN ■FAD The heterocyclic core of vitamin В 2 is isoalloxazine. Its compounds are called flavins, and proteins combined with flavins are called flavoproteins . These include enzyme being dehydrogenase which reacts with NADH 2 . Therefore, this flavoprotein, as a rule, does not react directly with oxidizing organic compounds, therefore it is called secondary dehydrogenase . At the same time, there are substrates that are directly oxidized by flavoproteins, they transport the detached protons and electrons to oxygen, and as a result, not water, but hydrogen oxide is 107