Oxidase Type Research Articles

N-(2-cyanoethyl)tranylcypromine, a potential prodrug of tranylcypromine: its disposition and interaction with catecholamine neurotransmitters in brain.

The disposition of the N-cyanoethyl analogue of tranylcypromine (TCP) and the TCP formed from it have been studied in the rat brain following intraperitoneal (ip) administration (0.1 mmol/kg) and the resultant data compared with those obtained following an equimolar dose of TCP. Brain concentrations of the neurotransmitter amines dopamine (DA) and noradrenaline (NA) have also been determined, as well as the percentage inhibition of monoamine oxidase (MAO) types A and B. Our results indicate that the N-cyanoethyl analogue may be a useful prodrug of TCP, providing lower but more sustained concentrations of TCP in brain. Brain levels of DA were increased in a similar pattern after CE-TCP or TCP. Brain levels of NA were decreased by TCP at most time intervals, while CE-TCP produced a much less pronounced effect. Both CE-TCP and TCP inhibited MAO-A and MAO-B, with maximum inhibition occurring 60 min after CE-TCP dosing and 30 min after dosing with TCP, times at which brain concentrations of CE-TCP and TCP were at the maximum.

13] Purification of the aa3-type cytochrome-c oxidase from Rhodopseudomonas sphaeroides

This chapter describes the purification of the aa 3 -type cytochrome-c oxidase from Rhodopseudomonas sphaeroides . The chapter outlines the procedures for the preparation of the bacterial membranes and purification of the oxidase. R. sphaeroides is a nonsulfur bacterium that, when grown anaerobically in the light, develops a photosynthetic apparatus. In the dark and in the presence of oxygen, the photosynthetic apparatus is suppressed and the bacterium utilizes a respiratory chain. The cytochrome-c oxidase from R. sphaeroides can easily and quickly be prepared in small amounts. The enzyme is immunologically related to that found both in yeast mitochondria and P. denitrificans. This oxidase appears to be structurally similar to other bacterial aa 3 -type oxidases, though does not function as a proton pump. The success of the purification of the oxidase critically depends on the purity of the cytoplasmic membrane preparation.

15] Cytochrome c oxidase from Paracoccus denitrificans

Publisher Summary This chapter describes the cytochrome c from Paracoccus denitrificans . Most bacterial- (heme aa 3 ) type oxidases appear to closely match the eukaryotic enzyme in terms of redox ligands, spectral and kinetic properties, and, in some cases, even their ability to act as redox-linked proton pumps. Among the best-characterized bacterial oxidases is the one from Paracoccus denitrificans , a bacterium long known for its close relationship to mitochondria. The protocol presented in the chapter provides a description of important steps in the growth of the organism, the preparation of membranes, and the purification of reasonable amounts of the enzyme suitable for structural and functional studies. Protein estimation in the presence of sodium dodecyl sulfate, spectral heme determinations, metal quantitations by atomic absorption spectroscopy, enzyme activity measurements, reconstitution, immune precipitation, and gel electrophoresis are performed. Proton pumping measurements of reconstituted Paracoccus oxidase , kinetic data, EPR studies, sedimentation analysis, cytochrome c binding, and a partial amino acid sequence analysis are presented.

Histochemical localization of monoamine oxidase types A and B in the adrenal gland.

The distribution of monoamine oxidase types A and B within the adrenal gland was studied in several mammals by histochemical methods. Controls showed that the methods were valid. The bovine adrenal medulla contained mostly the B type enzyme, distributed heterogeneously, with some A type associated with endothelium, nerves, and cells surrounding the nerves. The bovine adrenal cortex showed a marked zonation of the two types of monoamine oxidase. The zona glomerulosa contained the B type enzyme and the zona fasciculata and zona reticularis contained the type A enzyme. The adrenal medulla of the dog, cat, and rat demonstrated relatively little enzyme activity and it appeared to be both type A and B. The adrenal cortex of these animals appeared to contain mostly the B type enzyme, except the canine zona reticularis, which contained some A type monoamine oxidase as well.

Cytochrome a1 of Nitrosomonas europaea resembles aa3-type cytochrome c oxidase in many respects

Cytochrome c oxidase of Nitrosomonas europaea has been called cytochrome a 1 by Erickson et al. (Erickson, R.H., Hooper, A.B. and Terry, K.R. (1972) Biochim. Biophys. Acta 283, 155–166) because the reduced form of their preparation had the α peak at 595 nm. In the present studies, the enzyme was purified to an electrophoretically almost homogeneous state and some of its properties were studied. The enzyme much resembled cytochrome aa 3-type oxidase although its reduced form showed the α peak at 597 nm. (1) The absorption spectra of the CO compound of the reduced enzyme and CN − compounds of the oxidized and reduced enzyme were similar to those of the respective compounds of cytochrome aa 3, as well as the absorption spectrum of the intact enzyme resembled that of the cytochrome. (2) The enzyme possessed two molecules of haem a and 1–2 atoms of copper in the molecule. (3) The enzyme molecule was composed of two kinds of subunits of M r 50000 and 33000, respectively, as are other bacterial cytochromes aa 3. Although the enzyme resembled other bacterial cytochromes aa 3 in many properties, it differed greatly in two properties; its CO compound was easily dissociated into the oxidized enzyme and CO in air, and 50% inhibition of its activity by CN − required approx. 100 μM of the reagent. The enzyme oxidized 0.57, 1.6 and 1.8 mol horse, Candida krusei and N. europaea ferrocytochromes c per s per mol haem a, respectively, in 10 mM phosphate buffer, pH 6.0. The turnover numbers with eukaryotic ferrocytochromes c were increased to 32 and 14, respectively, by addition of cardiolipin (14 μ · ml −1).

Normetanephrine and metanephrine oxidized by both types of monoamine oxidase.

Both normetanephrine and metanephrine were found to be oxidized by both types of monoamine oxidase in mouse liver mitochondria. Both Km and Vmax values of type B MAO for both substrates were higher than those of type A MAO, which caused the shift of inhibition curves with clorgyline and deprenyl according to the increase in substrate concentration.

Expression of A and B types of monoamine oxidase in differentiated neuroblastoma hybrid cells.

The total activities of monoamine oxidase (MAO) and the ratio of type B/type A activities were determined in mouse neuroblastoma N1E-115 cells, and in NX31T and NG108-15 hybrid cells derived from mouse neuroblastoma X rat sympathetic ganglion hybrid or mouse neuroblastoma X rat glioma hybrid cells. N1E-115 and NX31T cells possessed type A activities exclusively, although NG108-15 cells showed both type A (65-90%) and type B (10-35%) MAO activities. The activity of type A MAO in NX31T and N1E-115 cells was relatively constant during culturing periods in the presence or absence of dibutyryl cyclic AMP (Bt2cAMP), whereas total MAO activity and the ratio of type B MAO/type A MAO in NG108-15 cells increased as a function of culture periods. Prostaglandin E1 (PGE1) and theophylline, the best known combination to increase intracellular cyclic AMP content of NG108-15 cells, caused similar increases of MAO and of the type B/type A ratio in NG108-15 cells. The results suggest that MAO activity and expression of MAO B activity are regulated in NG108-15 cells in a cyclic AMP-dependent manner.

Cytochrome o type oxidase from Escherichia coli. Characterization of the enzyme and mechanism of electrochemical proton gradient generation.

Cytochrome o type oxidase purified from the membrane of Escherichia coli consists of four polypeptides (Mr 66000, 35000, 22000, and 17000), and the monomeric form predominates in octyl beta-D-glucopyranoside. The oxidase complex contains two b-type cytochromes (b-558 and b-563) and 2 mol of heme/mol of enzyme. Cytochrome o utilizes ubiquinol-1 and a number of other artificial electron donors as substrates but does not oxidize reduced cytochrome c or ferrocyanide. Activity is highly dependent upon exogenous phospholipids and/or Tween 20, and the quinone analogues 2-heptyl-4-hydroxyquinoline N-oxide and 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole are potent inhibitors. Proteoliposomes were formed by detergent dilution or dialysis in the presence of the oxidase and phospholipids, followed by freeze-thaw/sonication. Vesicles formed by this means are unilamellar and contain a random distribution of 85-90-A intramembranous particles on the convex and concave fracture surfaces. During oxidase turnover, the reconstituted system generates a proton electrochemical gradient (interior negative and alkaline) of -115 to -140 mV; however, respiratory control is minimal (i.e., respiratory control ratios of about 1.5 are observed). By using a glass electrode to measure changes in external pH and the fluorescence of entrapped 8-hydroxy-1,3,6-pyrenetrisulfonate to measure changes in internal pH, it is apparent that during ubiquinol oxidation, protons are released on the external surface of the membrane and consumed on the internal surface. In contrast, with N,N,N',-N'-tetramethyl-p-phenylenediamine, an electron donor that carries few protons at neutral pH, little change in external pH is observed until the protonophore carbonyl cyanide m-chlorophenylhydrazone is added, at which point the medium becomes alkaline. The results taken as a whole are consistent with the concept that oxidase turnover generates an electrical potential (interior negative) due to vectorial electron flow from the outer to the inner surface of the membrane. The pH gradient (interior alkaline), on the other hand, appears to result from scalar (i.e., nonvectorial) reactions that consume and release protons at the inner and/or outer surfaces of the membrane, respectively. In other words, cytochrome o oxidase from Escherichia coli does not appear to catalyze vectorial proton translocation.

Nonhemorrhagic infarcton of the thalamus

<h3>Abstract</h3> <i>Vibrio cholerae</i> respires both aerobically and anaerobically and, while oxygen may be available to it during infection, other terminal electron acceptors are proposed for population expansion during infection. Unlike gastrointestinal pathogens that stimulate significant inflammation leading to elevated levels of oxygen or alternative terminal electron acceptors, <i>V. cholerae</i> infections are not understood to induce a notable inflammatory response. To ascertain the respiration requirements of <i>V. cholerae</i> during infection, we used Multiplex Genome Editing by Natural Transformation (MuGENT) to create <i>V. cholerae</i> strains lacking aerobic or anaerobic respiration. <i>V. cholerae</i> strains lacking aerobic respiration were attenuated in infant mice 10⁵-fold relative to wild type, while strains lacking anaerobic respiration had no colonization defect, contrary to earlier work suggesting a role for anaerobic respiration during infection. Using several approaches, including one we developed for this work termed Comparative Multiplex PCR Amplicon Sequencing (CoMPAS), we determined that the <i>bd</i>-I and <i>cbb</i>₃ oxidases are essential for small intestinal colonization of <i>V. cholerae</i> in the infant mouse. The <i>bd</i>-I oxidase was also determined as the primary oxidase during growth outside the host, making <i>V. cholerae</i> the only example of a Gram-negative bacterial pathogen in which a <i>bd</i>-type oxidase is the primary oxidase for energy acquisition inside and outside of a host. <h3>Author Summary</h3> The bacterium that causes cholera, <i>Vibrio cholerae</i>, can grow with or without oxygen. When growing without oxygen it may use other molecules that serve the same purpose as oxygen, acting as a terminal electron acceptor in an energy-generating process known as respiration. Given the largely anaerobic nature of the gastrointestinal tract, and the lack of significant inflammation during cholera infection, a process that can stimulate elevated levels of oxygen and other terminal electron acceptors, we sought to understand the respiratory mechanisms of <i>V. cholerae</i> during infection. We used a powerful genome-editing method to construct mutant strains of <i>V. cholerae</i> lacking some or all of the complement of proteins required for aerobic or anaerobic respiration. By analyzing these mutants in the laboratory and in intestinal colonization of infant mice, we determined that the ability to respire without oxygen is completely dispensable for <i>V. cholerae</i> to thrive during infection. We determined that two of the four oxygen-dependent respiration mechanisms are essential for <i>V. cholerae</i> to grow during infection, with the other two dispensable for wild type levels of colonization.

Fate of hydralazine in man. II. Formation of tetrazolo(5,1-a)phthalazine in vivo and inhibition of monoamine oxidase by this metabolite.

Tetrazolo [5, 1-α] phthalazine (Tetra-P) was detected in the urine of a patient on hydralazine treatment. Tetra-P is a new type of monoamine oxidase (MAO) inhibitor.

The terminal oxidase of Photobacterium phosphoreum. A novel cytochrome

The terminal oxidase of Photobacterium phosphoreum has been purified to the electrophoretically homogeneous state and some of its properties have been studied. The enzyme catalyses oxidation of ascorbate in the presence of phenazine methosulphate or N, N, N′, N′-tetramethyl- p-phenylenediamine. The reaction is inhibited by cyanide. Nitrite at comparatively high concentrations inhibits the enzyme, but the enzyme does not catalyse nitrite reduction with ascorbate plus the electron mediator as the electron donor. The enzyme shows the absorption peaks at 632, 565, 534 and 436 nm in the reduced form. It has two kinds of haems: protohaem and haem d. Namely, the enzyme is a ‘cytochrome bd’-type oxidase; a novel cytochrome.

Catalytic activity of copper(II) complexes with carboxyphenylaminopyrim-idines (antiphlogistics) in model reactions of the oxidase and catalase types

Catalytic activity of copper(II) complexes with carboxyphenylaminopyrim-idines (antiphlogistics) in model reactions of the oxidase and catalase types

Degradation of the transmitter amines by specific types of monoamine oxidase

Publisher Summary This chapter discusses a study analyzing degradation of the transmitter amines by specific types of monoamine oxidases. Monoamine oxidase exists in multiple forms in mammalian tissue. Two forms of enzyme could be revealed in homogenates of rat brain with the drug, clorgyline. The enzyme most sensitive to clorgyline was designated as A and the enzyme that was more resistant to clorgyline was designated as B. The 1000-fold difference in the concentration of clorgyline required to block A and B enzyme activity in vitro suggests that it might be possible to block these enzymes selectively in vivo . Pargyline, which is similar in structure to clorgyline and deprenyl is an irreversible inhibitor of monoamine oxidase. In a study, it was found that deprenyl and clorgyline inhibited irreversibly also. When increasing doses of clorgyline or deprenyl were administered intravenously, there was a selective blockade of A or B enzyme activity of brain when assayed in vitro with the specific substrates for A and B enzymes, serotonin and phenylethylamine, respectively. Following the administration of clorgyline, which blocks primarily enzyme A activity, norepinephrine, serotonin and dopamine concentrations increased in brain.

Studies on Monoamine Oxidase (Report 13) Isolation of Two Different Types of Monoamine Oxidase from Beef Liver Mitochondria

Studies on Monoamine Oxidase (Report 13) Isolation of Two Different Types of Monoamine Oxidase from Beef Liver Mitochondria