3 Oxygenases: Dioxygenases

摘要: Publisher Summary Pyrocatechase was isolated from cells of a pseudomonad, which catalyzed oxidative ring cleavage the benzene catechol forming cis, cis-muconic acid as reaction product. This enzyme exhibited properties unlike those an oxidase or dehydrogenase because it not associated with any previously known coenzymes electron carriers, and none dyes artificial acceptors tested could replace oxygen oxidant. Biological oxidation proceeded exclusively by removal electrons hydrogen atoms substrates, directs addition molecular excluded consideration. Oxygen act only ultimate acceptor in biological that all incorporated into substrates are derived water. chapter proposes new term, “oxygenase” to designate enzymes catalyze fixation reactions, terms “di” “mono” oxygenases generally assigned enzymes. Dioxygenases defined catalyzing reactions both substrates. In many instances where one substrate can acceptor. play important roles biosynthesis, transformation, degradation essential metabolites, such amino acids, lipids, sugars, nucleic porphyrins, vitamins, hormones. They also crucial role various aromatic compounds drugs, insecticides, carcinogens.