Oxidation arginines

NO Arginine oxidation (haem) G-protein Haem oxidation... 

Fig. 4. Oxidation of arginine. 5-Hydroxy-2-aminovaleric acid, which is the arginine oxidation end product, may also be produced during oxidation of proline.

Nitric oxide, called also nitrogen monoxide ( NO), a (bioactive) free radical, is produced in various cells/tissues by NO-synthase (NOS) enzymes. The three distinct NOS isoforms are P j -related hemoproteins that during L-arginine oxidation to L-citmlline produce NO. Two of the permanently present enzymes that participate in the regulation of the blood vessel tonus are termed constitutive NOS (cNOS), while the third one is called an inducible NOS (iNOS). The level of NO produced by iNOS increases markedly during inflammation, a process accompanied with abundant production of the superoxide anion radical. 

The production of NO by NO-synthase (NOS) (Figure 12) involves two domains, a reductase which binds flavin and an oxygenase which comprises a heme unit to which the substrate L-arginine binds. Three different forms of NOS are known, an inducible (iNOS), an endothelial (eNOS) and a neuronal one (nNOS). The details of the arginine oxidation mechanism have been studied in recent years, but only at the level of free-radical formation as far as EPR is concerned, so that the heme related part has not been addressed in great detail since the last review. The free-radical part involves determination of not only NO but also the superoxide anion and the tetrahydrobiopterin radical, to name the most prominent representatives. For the purpose of the present context we only mention briefly some of the relevant investigations. The production of O2 from the nNOS oxygenase domain was reported, as was its release by iNOS and by eNOS. A review on this aspect has become available. The role of NO in relation ofNO and ONOO has been reviewed with respect to consequences in postischemic myocardium. The detection of the tetrahydrobiopterin radical in the first reaction cycle of eNOS and nNOS has been reported. The interplay... 

Particles from the blue-green algae Anacy sti s nidulans Synechococcu s leopoliensis) can catalyze O2 evolution with ferricyanide as acceptor in the light and the dark oxidation >f L-arginine (and other basic amino acids). The two eactions are both inhibited by o-phenanthroline, but respond to certain trivalent, divalent and monovalent cations (like e. g. La +, Ca " " and K" ") in different ways. These metals stimulate the Hill reaction with ferricyanide as acceptor, but totally inhibit L-arginine oxidation. 

Active photosystem II particles have also been isolated from Anacystis membrane fractions. They can catalyze 2,6-di-chloroindophenol reduction with diphenyIcarbazide as donor in the light. They retain L-arginine oxidation activity in the presence of EDTA. Both reactions are inhibited by o-phenanthroline. Moreover, it could be shown that one of the protein bands which has been shown to be characteristic for photosystem II particles of A, nidulans (Koenig, Vernon, 1981), CO-chromatographs with the purified L-amino acid oxidase on SDS gels. An antibody prepared to the purified L-amino acid oxidase also gave a precipitin line with detergent-treated photosystem II particles (Pistorius, Voss,... 

That is, Mg2+ and Ba2+ may be more effective in preventing the rebinding of Mn " " than they are in causing Mn2+ removal. We do not know whether the Mn + is bound to the L-amino acid oxidase. If the enzyme was responsible for binding both ions, Mn2+ would probably be bound at a different site than Ca t. we have previously shown that some transition metals inhibit the L-arginine oxidation in a lower concentration range than the alkali earth metals (Pistorius, Voss, 1980). A dual requirement of Mn2+ and Ca2+ for the activation of the latent water-oxidation center has also been shown for intact chloroplasts isolated from wheat leaves grown under intermittent flash illumination (Ono,... 

Our experience conditions us to focus on the organic components of the reaction—l arginine and l citrul line—and to give less attention to the inorganic one—nitric oxide (nitrogen monoxide NO) To do so however would lead us to overlook one of the most important discoveries in biology in the last quarter of the twentieth century... 

RL Cutler, AM Davies, S Creighton, A Warshel, GR Moore, M Smith, AG Mauk. Role of arginine-38 in regulation of the cytochrome c oxidation-reduction equilibrium. Biochemistry 28 3188-3197, 1989. 

NO synthases (NOS, L-arginine, NADPH oxygen oxi-doreductases, nitric oxide forming EC 1.14.13.39) represent a family of enzymes that catalyze the formation of nitric oxide (NO) from the amino acid L-arginine. In mammals, three isoforms of NOS have been identified. They are termed neuronal NOS (nNOS, NOS I, NOS1), inducible NOS (iNOS, NOS H, NOS2), and endothelial... 

Arginine serves as the formamidine donor for creatine biosynthesis, participates in polyamine biosynthesis, and provides the nitrogen of nitric oxide (NO). 

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