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PubMed1976

Neurogenic influences of bilateral adrenalectomy on monoamine oxidase.

Bilateral adrenalectomy (10 days) increased the monoamine oxidase activity of the rat heart, vas deferens, spleen, superior cervical ganglion, and hypothalamus but not that of the rest of the brain, kidney, and liver. Experiments were made to determine whether the increased activity was due to neurogenic influences and whether the enhanced activity of monoamine oxidase was intra- or extraneuronally located. Ganglionic blockade with chlorisondamine failed to alter the rise in cardiac monoamine oxidase. Likewise, superior cervical ganglion monoamine oxidase was unaffected by surgical denervation. 6-Hydroxydopamine abolished the increase in monoamine oxidase activity of the vas deferens, spleen, and superior cervical ganglion but failed to alter that of the kidney, hypothalamus, and the rest of the brain. Cardiac monoamine oxidase was reduced markedly by 6-hydroxydopamine, but the remaining activity was still significantly elevated over the respective control values. The data suggest that the increase in organ monoamine oxidase is predominantly of neuronal origin and that this increase is not due to transsynaptic induction.

Adrenal Glands↗
PubMed1982

Plasma membrane and phagosome localisation of the activated NADPH oxidase in elicited peritoneal macrophages of the guinea-pig.

The subcellular distribution of the NADPH oxidase of guinea-pig peritoneal-elicited macrophages was investigated. Post-nuclear supernatants obtained from PMA-stimulated macrophages were fractionated in discontinuous sucrose gradients. The NADPH oxidase was found to be enriched at the interface between 20 and 34 per cent sucrose. This interface was also enriched in 5'-nucleotidase, a plasma membrane marker and in glucose-6-phosphatase and NADPH-cytochrome c reductase, two endoplasmic reticulum markers. The distribution in the gradient of beta-glucuronidase, a marker of lysosomes and of succinate dehydrogenase, a marker of mitochondria was clearly different from that of NADPH oxidase and of the markers of plasma membrane and of endoplasmic reticulum. These results indicated that in stimulated-elicited macrophages the NADPH oxidase is associated with a membrane fraction. With the fractionation technique employed it was not possible to clarify whether the oxidase is located in the plasma membrane or in the endoplasmic reticulum. In order to clarify this matter the isolation of phagosomes was performed. NADPH oxidase was found to be enriched in the phagosomal fraction. Phagosomes were also found to be enriched in the plasma membrane marker 5'-nucleotidase. Glucose-6-phosphatase,, a marker of endoplasmic reticulum, and beta-glucuronidase, a marker of lysosomes were not enriched in the phagosomal fraction. The results obtained clearly suggest that the activated NADPH oxidase of peritoneal elicited macrophages of guinea pig is located in the plasma membrane.

Animals↗
PubMed1997

Folate utilization by monomeric versus heterotetrameric sarcosine oxidases.

There are two types of bacterial sarcosine oxidases. The heterotetrameric enzymes contain subunits ranging in size from about 10 to 100 kDa, noncovalently bound FAD and NAD+, and covalently bound FMN attached to the beta subunit (42-45 kDa). Monomeric sarcosine oxidases are similar in size to the beta subunit in the heterotetramers and contain covalently bound FAD. Formaldehyde formation during sarcosine oxidation by several heterotetrameric sarcosine oxidases was suppressed in the presence of 50 microM [6S]-tetrahydrofolate, accompanied by a 25-50% increase in the rate of sarcosine oxidation. In contrast, [6S]-tetrahydrofolate caused only a modest decrease in the rate of formaldehyde production with monomeric sarcosine oxidases (approximately 25%), an effect which was virtually entirely attributable to an accompanying decrease in the rate of sarcosine oxidation. In the presence of 100 microM [6R,S]-tetrahydropteroyltriglutamate [H4Pte(Glu)3], the heterotetrameric enzymes catalyzed the formation of 5,10-methylenetetrahydropteroyltriglutamate [5,10-CH2-H4Pte(Glu)3] at a rate which was 35-60% faster than the rate of sarcosine oxidation in the absence of folate. An apparent Km value of 3.1 microM was estimated for [6S]-H4Pte(Glu)3 with the heterotetrameric corynebacterial sarcosine oxidase. In contrast, slow formation of 5,10-CH2-H4Pte(glu)3 was detected during sarcosine oxidation with monomeric sarcosine oxidases, attributable to the nonenzymatic reaction of free formaldehyde with H4Pte(Glu)3. The results show that only the heterotetrameric sarcosine oxidases can use tetrahydrofolates as substrates and, in this regard, they resemble mammalian sarcosine and dimethylglycine dehydrogenases.

Corynebacterium↗
PubMed1996

In situ detection of diamine oxidase activity using enhanced chemiluminescence.

In need of a simple and sensitive method for detection of diamine oxidase (EC 1.4.3.6) activity in connection with diamine oxidase purification from human placenta, we have developed an enhanced chemiluminescence method using putrescine as substrate and horseradish peroxidase and luminol for the detection of the H2O2 produced by diamine oxidase. The method allows direct detection of small amounts of diamine oxidase in serum samples after agarose gel electrophoresis and allows visualization of diamine oxidase activity in tissue sections. Employing this method we have detected diamine oxidase in sera from cow, horse, monkey, rabbit, and pregnant women. On tissue sections from term human placenta diamine oxidase activity was exclusively localized to the maternal side and was concentrated in vessels and fibrinoid areas.

Amine Oxidase (Copper-Containing)↗
PubMed1998

4-Hydroxyanisole: the most suitable monophenolic substrate for determining spectrophotometrically the monophenolase activity of polyphenol oxidase from fruits and vegetables.

A continuous spectrophotometric method for determining the monophenolase activity of polyphenol oxidase from several plant sources is described. This assay method is based on the coupling reaction between 3-methyl-2-benzothiazolinone hydrazone and the quinone product of the oxidation of 4-hydroxyanisole in the presence of polyphenol oxidase. 4-Hydroxyanisole proved to be the best monophenol assayed to measure the monophenolase activity of polyphenol oxidase from apple, artichoke, avocado, medlar, pear, and strawberry. Kinetic constants of 4-hydroxyanisole were compared to those of p-hydroxyphenyl propionic acid, a very sensitive monophenol previously reported to assay the monophenolase activity of polyphenol oxidase from apple, pear, and mushroom. The high values of the maximum steady state rate obtained for 4-hydroxyanisole suggest the existence of high catalytic constant toward this monophenol. These kinetic values were supported by nuclear magnetic resonance assays which predicted the highest reactivity of 4-hydroxyanisole. Therefore nuclear magnetic resonance assays proved to be a valuable and useful tool to predict the best monophenolic substrate for plant polyphenol oxidases. The 3-methyl-2-benzothiazlolinone-adduct for 4-hydroxyanisole was stable, with high molar absorptivity at the optimum pHs of the polyphenol oxidases assayed. All this together makes the use of 4-hydroxyanisol as monophenolic substrate and 3-methyl-2-benzothiazolinone as coupling reagent the most sensitive and precise assay method up to date reported in the literature to determine the monophenolas activity of polyphenol oxidase from fruits and vegetables.

Anisoles↗
PubMed2000

Purification, cloning, and three-dimensional structure prediction of Micrococcus luteus FAD-containing tyramine oxidase.

The FAD-containing tyramine oxidase enzyme and gene from the Gram (+) bacterium Micrococcus luteus were isolated, and computer prediction was used to propose a preliminary 3D model of the protein. A 2.8-kb Sau3AI fragment containing the structural gene of tyramine oxidase was cloned from a M. luteus genomic DNA library. The 1332 bp gene encodes a protein of 443 amino acids, with a calculated molecular mass of 49.1 kDa. The enzyme was found to be a homodimer with a molecular weight of 49,000. It oxidizes tyramine, adrenaline, 3-hydroxytyramine, dopamine, and noradrenaline, and was reversibly inhibited by FAD-containing monoamine oxidase A and B specific inhibitors. Sequence comparison show that tyramine oxidase is smaller than other FAD-amine oxidases but that it contains well-conserved amino acid residues reported in all other FAD-amine oxidases. A hypothetical three-dimensional structure of tyramine oxidase has also been proposed based on secondary structure predictions, threading, and comparative modeling.

Amino Acid Sequence↗
PubMed1990

Ischaemic brain oedema and xanthine-xanthine oxidase system.

The formation of oxygen-derived free radicals in cerebral ischaemia has been implicated in altering the BBB permeability, cause oedema and tissue damage. However little attention has been paid regarding the involvement of xanthine oxidase in the cerebral ischaemic events. Recently we demonstrated that cerebral ischaemia promotes the conversion of xanthine oxidase type D (nicotinamide adenine dinucleotide-dependent dehydrogenase) to type 0 (oxygen-dependent superoxide-producing oxidase). This investigation was concerned with elucidating the relationship between the conversion of xanthide oxidase and the duration of brain ischaemia. Four vessel-occlusion served as a model for the induction of cerebral ischaemia in rats. Xanthine oxidase was assayed by high pressure liquid chromatography using ultraviolet and electrochemical detection. The enzymatic conversion of xanthine oxidase from type D to type O increased with time from 7.6-15% during 5 min ischaemia to 27% and 36% at 15 min and 30 min after ischaemia, respectively. These results support the contention that xanthine oxidase may participate in free radical-induced ischaemic brain oedema.

Animals↗
PubMed1995

Studies on the import and processing of the alternative oxidase precursor by isolated soybean mitochondria.

Import of the synthetic precursor of the alternative oxidase from soybean was shown to be dependent on a membrane potential and ATP. The membrane potential in soybean mitochondria may be formed either by respiration through the cytochrome pathway, or through the alternative oxidase pathway with NAD(+)-linked substrates. Import of the alternative oxidase precursor in the presence of succinate as respiratory substrate was inhibited by KCN. Import in the presence of malate was insensitive to KCN and SHAM added separately, but was inhibited by KCN and SHAM added together (inhibitors of the cytochrome and alternative oxidases respectively). Import of the alternative oxidase was accompanied by processing of the precursor to a single 32 kDa product in both cotyledon and root mitochondria. This product had a different mobility than the two alternative oxidase bands detected by immunological means (34 and 36 kDa), suggesting that the enzyme had been modified in situ. When the cDNA clone of the alternative oxidase was modified by a single mutation (-2 Arg changed to -2 Gly), the processing of the precursor was inhibited.

Amino Acid Sequence↗
PubMed1995

Monoamine oxidase-B-positive granular structures in the hippocampus of aged senescence-accelerated mouse (SAMP8).

We examined the histochemical localization of monoamine oxidase in the hippocampus of young and old senescence-accelerated mouse (SAM). We found a monoamine oxidase-B-positive granular structure (MGS) in the hippocampus of old SAMP8, an accelerated senescence-prone line of SAM. The MGS was a round-shaped granular structure of 0.5 to 5 microns diameter and usually formed a cluster, the largest diameter of which ranged from 50 to 150 microns. No MGS were found in the hippocampus of young SAMP8 or of young SAMR1, an accelerated senescence resistant line of SAM, and only few, if any, were seen in old SAMR1. A monoamine oxidase-positive astrocyte was usually observed in the central area of each cluster of MGS. Furthermore, the MGS was in close anatomical relationship with monoamine oxidase-positive astrocytic processes. The enzyme inhibition experiments showed that monoamine oxidase activities localized in the MGS and astrocytes were both predominantly of type B. These findings suggest MGS occurs at least partly in monoamine oxidase-B-positive astrocytes. Furthermore, the MGS was similar to a periodic acid-Schiff-positive granular structure, a polyglucosan body previously documented in the brains of old SAMP8 and some other aged mice strains including C57BL/6 and nude mice, in terms of their size, morphological appearances and topographical distribution in the hippocampus. Thus, the present results suggest that monoamine oxidase type B is a proteinaceous component of the periodic acid-Schiff-positive granular structure in aged mice brains, and might provide some clues for clarifying the mechanisms of age-related occurrence of periodic acid-Schiff-positive granular structures in mice brains.

Aging↗
PubMed1988

Subcellular localization and dynamics of components of the respiratory burst oxidase.

Membrane and cytosolic factors cooperate to generate NADPH-oxidase. The study of the syndrome of NADPH-oxidase deficiencies, chronic granulomatous disease, has enabled the identification of two membrane factors: a flavin adenine dinucleotide flavoprotein and a b cytochrome. The nature of the cytosolic components is still unknown, but a 47-kD protein, whose phosphorylation occurs in parallel with the generation of a respiratory burst in intact cells, seems to be one of the cytosolic factors. The subcellular localization of the membrane-bound NADPH-oxidase components has been studied in neutrophils: In unstimulated cells, only a minute fraction of the NADPH-oxidase components is localized in the plasma membrane, whereas approximately 80% is localized in the membrane of the specific granules and the majority of the rest is in a newly described membrane-bound compartment, the secretory granules, identified by latent alkaline phosphatase. During stimulation, these NADPH-oxidase components are translocated to the plasma membrane as a result of fusion of granule membrane with plasma membrane. Only the NADPH-oxidase components present in the plasma membrane are incorporated in the respiratory burst oxidase generated in intact cells.

Animals↗
PubMed1988

Decreased plasma postheparin diamine oxidase levels in celiac disease.

The highest diamine oxidase activity is contained in small-bowel mucosa and, after heparin administration, the enzyme is released by the intestine into the plasma. Previous experimental studies showed that measurement of plasma postheparin diamine oxidase activity is a sensitive test for quantitating the length and severity of small-bowel mucosal injury. On this basis, we measured plasma diamine oxidase activity in celiac disease, a condition characterized by a loss of mature enterocyte mass. Twenty-five untreated celiac patients, 21 celiac patients on a gluten-free diet, 16 patients with small-bowel diseases other than celiac disease (abnormal controls), and 18 healthy controls were studied. Diamine oxidase activity was measured using [14C]putrescine as substrate and expressed as units per milliliter of plasma. Basal diamine oxidase levels in controls and patients were too low for significant differences between the groups to be detected. After preliminary experiments in which, on separate occasions, heparin was intravenously administered at doses of 75 and 150 units/kg and in which the second blood sample was taken 10 and 30 min after heparin injection, it was decided to use the 150 unit/kg dose and to measure plasma diamine oxidase activity in the blood sample taken 10 min after heparin stimulation in all the remaining subjects taking part in the study. Postheparin diamine oxidase levels were significantly lower in untreated celiac patients (mean 1.53 units/ml) than in healthy controls (mean 5.85), treated celiac patients (mean 4.82), and abnormal controls (mean 2.62). Except in three patients, no overlap between healthy controls and untreated celiac patients was observed. No significant difference was detected between healthy controls and treated celiac patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Mechanisms for the activation/electron transfer of neutrophil NADPH-oxidase complex and molecular pathology of chronic granulomatous disease.

Professional phagocytes, neutrophils, possess a unique membrane-associated NADPH-oxidase system, dormant in resting cells, which becomes activated upon exposure to the appropriate stimuli and catalyzes the one-electron reduction of molecular oxygen to superoxide, O2-. Oxidase activation involves the assembly, in the plasma membrane, of membrane-bound and cytosolic constituents of the oxidase system, which are disassembled in the resting state. The oxidase system consists of two plasma membrane-bound components; low-potential cytochrome b558, which is composed of two subunits of 22-kDa, and 91-kDa, and a possible flavoprotein related to the electron transport between NADPH and cytochrome b558. Recent reports have indicated that FAD-binding sites of the oxidase are contained in cytochrome b558. At least two cytosolic components, 67-kDa protein and a phosphorylated 47-kDa protein, are known to translocate to the plasma membrane, ensuring assembly of an active O2(-)-generating NADPH-oxidase system. It is the purpose of this review to focus on recent data concerning electron transfer mechanisms of the activated neutrophil NADPH-oxidase complex and molecular pathology of chronic granulomatous disease.

Electron Transport↗
PubMed1989

Lysosomal enzyme leakage during the hypoxanthine/xanthine oxidase reaction.

Impairment of lysosomal stability due to reactive oxygen species generated during the oxidation of hypoxanthine by xanthine oxidase was studied in rat liver lysosomes isolated in a discontinuous Nycodenz gradient. Production of O2.- and H2O2 during the hypoxanthine/xanthine oxidase reaction occurred for at least 5 min, while lysosomal damage, indicated by the release of N-acetyl-beta-glucosaminidase, occurred within 30 s, there being no further damage to these organelles thereafter. The extent of lysosomal enzyme release increased with increasing xanthine oxidase concentration. Superoxide dismutase and catalase did not prevent lysosomal damage during the hypoxanthine/xanthine oxidase reaction. Lysosomes reduced xanthine oxidase activity, as assessed in terms of O2 consumption, only slightly but substantially inhibited in a competitive manner the O2.- -mediated reduction of cytochrome c. This inhibition was almost completely reversed by potassium cyanide, thus pointing to the presence of a cyanide-sensitive superoxide dismutase in the lysosomal fraction. However, potassium cyanide did not affect the hypoxanthine/xanthine oxidase-mediated lysosomal damage, thus suggesting an inability of the lysosomal superoxide dismutase to protect the organelles. Negligible malondialdehyde formation was observed in the lysosomes either during the hypoxanthine/xanthine oxidase reaction or with different selective experimental approaches known to produce lipid peroxidation in other organelles such as microsomes and mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗
PubMed1999

Purification and spectroscopic studies on catechol oxidases from Lycopus europaeus and Populus nigra: evidence for a dinuclear copper center of type 3 and spectroscopic similarities to tyrosinase and hemocyanin.

We purified two catechol oxidases from Lycopus europaeus and Populus nigra which only catalyze the oxidation of catechols to quinones without hydroxylating tyrosine. The molecular mass of the Lycopus enzyme was determined to 39,800 Da and the mass of the Populus enzyme was determined to 56,050 Da. Both catechol oxidases are inhibited by thiourea, N-phenylthiourea, dithiocarbamate, and cyanide, but show different pH behavior using catechol as substrate. Atomic absorption spectrosopic analysis found 1.5 copper atoms per protein molecule. Using EPR spectroscopy we determined 1.8 Cu per molecule catechol oxidase. Furthermore, EPR spectroscopy demonstrated that catechol oxidase is a copper enzyme of type 3. The lack of an EPR signal is due to strong antiferromagnetic coupling that requires a bridging ligand between the two copper ions in the met preparation. Addition to H2O2 to both enzymes leads to oxy catechol oxidase. In the UV/Vis spectrum two new absorption bands occur at 345 nm and 580 nm. In accordance with the oxy forms of hemocyanin and tyrosinase the absorption band at 345 nm is due to an O2(2-) (pi sigma *)-->Cu(II) (dx2 - y2) charge transfer (CT) transition. The absorption band at 580 nm corresponds to the second O2(2)- (pi v*)-->Cu(II) (dx2 - y2) CT transition. The UV/Vis bands in combination with the resonance Raman spectra of oxy catechol oxidase indicate a mu-eta 2:eta 2 binding mode for dioxygen. The intense resonance Raman peak at 277 cm-1, belonging to a Cu-N (axial His) stretching mode, suggests that catechol oxidase has six terminal His ligands, as known for molluscan and arthropodan hemocyanin.

Binding Sites↗
PubMed1983

Chemical and catalytic properties of the peroxisomal acyl-coenzyme A oxidase from Candida tropicalis.

The peroxisomal acyl-CoA oxidase has been purified from extracts of the yeast Candida tropicalis grown with alkanes as the principal energy source. The enzyme has a molecular weight of 552,000 and a subunit molecular weight of 72,100. Using an experimentally determined molar extinction coefficient for the enzyme-bound flavin, a minimum molecular weight of 146,700 was determined. Based on these data, the oxidase contains eight perhaps identical subunits and four equivalents of FAD. No other beta-oxidation enzyme activities are detected in purified preparations of the oxidase. The oxidase flavin does not react with sulfite to form an N(5) flavin-sulfite complex. Photochemical reduction of the oxidase flavin yields a red semiquinone; however, the yield of semiquinone is strongly pH dependent. The yield of semiquinone is significantly reduced below pH 7.5. The flavin semiquinone can be further reduced to the hydroquinone. The behavior of the oxidase flavin during photoreduction and its reactivity toward sulfite are interpreted to reflect the interaction in the N(1)-C(2)O region of the flavin with a group on the protein which acts as a hydrogen-bond acceptor. Like the acyl-CoA dehydrogenases which catalyze the same transformation of acyl-CoA substrates, the oxidase is inactivated by the acetylenic substrate analog, 3-octynoyl-CoA, which acts as an active site-directed inhibitor.

Acyl-CoA Oxidase↗
PubMed1989

Stabilization of the superoxide-generating respiratory burst oxidase of human neutrophil plasma membrane by crosslinking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide.

The superoxide-generating respiratory burst oxidase (NADPH-oxidase) of neutrophil plasma membranes is known to be highly unstable. In an attempt to stabilize the enzyme, we investigated the effect of crosslinking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The stability of superoxide-generating activity of plasma membrane was significantly enhanced by crosslinking. The half-life (t1/2) of the activity at 37 degrees C in the absence of crosslinker was about 2 min. Crosslinking extended the t1/2 significantly. Crosslinked material exhibited a biphasic loss of activity: about half was lost in each phase with respective t1/2 values of 20 and 240 min. The lifetime of the crosslinked material at 37 degrees C was further extended (about sixfold) with 30% glycerol, and the crosslinked material was completely stable for more than 2 weeks if stored on ice. Crosslinking also stabilized the activity to the effects of high salt and detergent, both of which have inactivating effects on the oxidase. In addition, crosslinking stabilizes not only the Vm but also the Km of the enzyme, which was noted to increase upon storage in the absence of crosslinking. Unlike the native material, the crosslinked oxidase failed to be stimulated (and in fact was inhibited) by phosphatidylserine, recently reported to be an activator of the oxidase (Tamura et al. (1988) J. Biol. Chem. 263, 17,621-17,626). The crosslinked plasma membrane provides a useful stabilized system for kinetic studies. When the activated plasma membrane was treated with EDC, the stabilized oxidase could not be solubilized effectively using detergents, since greater than 95% of the activity remained with the pellet following centrifugation, perhaps due to crosslinking to the cytoskeleton. However, when the activity was first detergent-solubilized, the soluble activity was also stabilized by EDC. This solubilized, crosslinked material may provide useful starting material for subsequent isolation and characterization of a stabilized active NADPH-oxidase.

Carbodiimides↗
PubMed1990

Effect of glutaraldehyde on NADPH oxidase system of guinea pig polymorphonuclear leukocytes.

In an attempt to elucidate properties and activation mechanisms of the NADPH oxidase system, which is known to be responsible for the production of superoxide anion (O2-) in cell membranes of polymorphonuclear leukocytes (PMNL), intact guinea pig PMNL were treated with glutaraldehyde, a protein crosslinking reagent, before or after stimulation with phorbol 12-myristate 13-acetate (PMA). Then, PMNL were disrupted and NADPH oxidase activity was measured. After the treatment of resting PMNL with glutaraldehyde, NADPH oxidase was no longer activated by PMA. On the other hand, the NADPH oxidase activity enhanced by PMA in advance was markedly retained by the glutaraldehyde treatment of such PMA-stimulated PMNL as compared to that in untreated cells. Similar retention by glutaraldehyde of the stimulated NADPH oxidase activity was observed in PMNL stimulated by formyl-methionyl-leucyl-phenylalanine (FMLP) and cytochalasin D. Furthermore, the oxidase activity of glutaraldehyde-treated PMNL was stable during incubation at 37 degrees C, the half life of the oxidase activity of the treated PMNL being more than 90 min whereas that of the untreated PMNL is about 15 min. This ability of the glutaraldehyde treatment to retain the activity was also observed against inactivation by high concentrations of NaCl and by positively charged alkylamine.

Aldehydes↗
PubMed1990

Involvement of membrane charges in constituting the active form of NADPH oxidase in guinea pig polymorphonuclear leukocytes.

NADPH oxidase activity in a membrane fraction prepared from phorbol 12-myristate 13-acetate (PMA)-stimulated guinea pig polymorphonuclear leukocytes (PMNL) was inhibited by positively charged myristylamine. The inhibitory effect of myristylamine was significantly suppressed by simultaneous addition of a negatively charged fatty acid, such as myristic acid. However, the suppression by myristylamine was not sufficiently restored when myristic acid was added later. On the other hand, pretreatment of PMA-stimulated PMNL with glutaraldehyde, a protein crosslinking reagent, stabilized NADPH oxidase activity against inhibition by myristylamine, but not against that by p-chloromercuribenzenesulfonic acid. In a cell-free system of reconstituted plasma membrane and cytosolic fractions prepared from unstimulated PMNL, arachidonic acid-stimulated NADPH oxidase activity was also inhibited by myristylamine. During the activation of NADPH oxidase by PMA in intact PMNL and by arachidonic acid in the cell-free system, cytosolic activation factor(s) translocated to plasma membranes. The bound cytosolic activation factor(s) was released from the membranes by myristylamine, accompanied by a loss of NADPH oxidase activity. It is plausible from these results that the inhibitory effect of alkylamine on NADPH oxidase is due to induction of the decoupling and/or dissociation of the cytosolic activation component(s) from the activated NADPH oxidase complex by increments of positive charges in the membranes, and that the glutaraldehyde treatment prevents the dissociation of component(s).

Amines↗