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At least 253 records · Page 14Linked to original sources
PubMed1994

Decrease in cytochrome c oxidase and cytochrome oxidase subunit I messenger RNA levels in preeclamptic pregnancies.

OBJECTIVE: To elucidate the possible relation between mitochondrial gene expression and placental dysfunction. METHODS: We measured the activity of cytochrome c oxidase and the expression of cytochrome oxidase subunit I in mitochondria from human placentas of women whose gestations were appropriate for gestational age (AGA) and those with preeclampsia. In addition, the amounts of normal mtDNA and deleted mitochondrial DNA were examined in the two groups by Southern blot analysis and polymerase chain reaction, respectively. RESULTS: Cytochrome c oxidase activity and expression of cytochrome oxidase subunit I were significantly lower in the preeclamptic group than in the AGA group. There were no differences between the groups in the amounts of mitochondrial DNA. In addition, no mutant mitochondrial DNA with a 4977-base pair deletion was detected in the two groups. CONCLUSION: These results suggest that reduced expression of the mitochondrial gene is involved in placental dysfunction in preeclamptic pregnancy.

Actins↗
PubMed1993

Metabolism-based transformation of myoglobin to an oxidase by BrCCl3 and molecular modeling of the oxidase form.

The stoichiometric reductive debromination of BrCCl3 to a trichloromethyl radical by myoglobin caused the prosthetic heme to become covalently cross-linked to the protein moiety and transformed myoglobin from an oxygen storage protein to an oxidase. This was shown in experiments in which oxygen consumption was measured during redox cycling of the altered myoglobin in the presence of ascorbate or an enzymatic reducing system containing diaphorase and NADH. Redox cycling eventually led to loss of the protein-bound heme adduct and oxidase activity of myoglobin. We have used molecular modeling and the known structure of the protein-bound heme adduct to identify probable mechanisms for transformation of myoglobin to an oxidase. Based on these modeling studies, the most likely structure of the experimentally observed adduct involves ligation to the heme iron of the epsilon-nitrogen atom of histidine 97 and/or that of histidine 64. The model structures revealed access of solvent to the heme active site, which could facilitate oxygen reduction. The transformation of myoglobins and perhaps other hemoproteins to oxidases may have toxicological importance in causing the tissue damage resulting from exposure to various xenobiotics and endogenous chemicals as well as explaining how hemoproteins are inactivated during catalysis.

Animals↗
PubMed1991

Plasma amine oxidase activities in Norrie disease patients with an X-chromosomal deletion affecting monoamine oxidase.

Two individuals with an X-chromosomal deletion were recently found to lack the genes encoding monoamine oxidase type A (MAO-A) and MAO-B. This abnormality was associated with almost total (90%) reductions in the oxidatively deaminated urinary metabolites of the MAO-A substrate, norepinephrine, and with marked (100-fold) increases in an MAO-B substrate, phenylethylamine, confirming systemic functional consequences of the genetic enzyme deficiency. However, urinary concentrations of the deaminated metabolites of dopamine and serotonin (5-HT) were essentially normal. To investigate other deaminating systems besides MAO-A and MAO-B that might produce these metabolites of dopamine and 5-HT, we examined plasma amine oxidase (AO) activity in these two patients and two additional patients with the same X-chromosomal deletion. Normal plasma AO activity was found in all four Norrie disease-deletion patients, in four patients with classic Norrie disease without a chromosomal deletion, and in family members of patients from both groups. Marked plasma amine metabolite abnormalities and essentially absent platelet MAO-B activity were found in all four Norrie disease-deletion patients, but in none of the other subjects in the two comparison groups. These results indicate that plasma AO is encoded by gene(s) independent of those for MAO-A and MAO-B, and raise the possibility that plasma AO, and perhaps the closely related tissue AO, benzylamine oxidase, as well as other atypical AOs or MAOs encoded independently from MAO-A and MAO-B may contribute to the oxidative deamination of dopamine and 5-HT in humans.

Adolescent↗
PubMed2006

Increased monoamine oxidase and semicarbazide-sensitive amine oxidase activities in white adipose tissue of obese dogs fed a high-fat diet.

Adipocytes express two types of amine oxidases: the cell surface semicarbazide-sensitive amine oxidase (SSAO) and the mitochondrial monoamine oxidase (MAO). In human abdominal subcutaneous adipose tissue, it has been reported that SSAO substrates stimulate glucose transport and inhibit lipolysis while MAO activity is decreased in obese patients when compared to age-matched controls. However, no information has been reported on visceral WAT. To further investigate the obesity-induced regulations of MAO and SSAO in white adipose tissue (WAT) from different anatomical locations, enzyme activities and mRNA abundance have been determined on tissue biopsies from control and high-fat fed dogs, an obesity model already described to be associated with arterial hypertension and hyperinsulinemia. MAO activity was increased in the enlarged omental WAT of diet-induced obese dogs, but not in their mesenteric WAT, another intra-abdominal fat depot. Subcutaneous WAT did not exhibit any change in MAO activity, as did the richest MAO-containing tissue: liver. Similarly, SSAO was increased in omental WAT of diet-induced obese dogs, but was not modified in other WAT and in aorta. The increase in SSAO activity observed in omental WAT likely results from an increased expression of the AOC3 gene since mRNA abundance and maximal benzylamine oxidation velocity were increased. Finally, plasma SSAO was decreased in obese dogs. Although the observed regulations differ from those found in subcutaneous WAT of obese patients, this canine model shows a tissue- and site-specific regulation of peripheral MAO and SSAO in obesity.

Adipose Tissue, White↗
PubMed1985

Inactivation of Escherichia coli glutamine synthetase by xanthine oxidase, nicotinate hydroxylase, horseradish peroxidase, or glucose oxidase: effects of ferredoxin, putidaredoxin, and menadione.

Previous studies have shown that several mixed-function oxidation (MFO) systems are capable of catalyzing the inactivation of glutamine synthetase (GS) [R.L. Levine, C. N. Oliver, R. M. Fulks, and E. R. Stadtman (1978) Proc. Natl. Acad. Sci. USA 78, 2120-2124] and a number of the other enzymes [L. Fucci, C. N. Oliver, M. J. Coon, and E. R. Stadtman (1983) Proc. Natl. Acad. Sci. USA 80, 1521-1525]. It has now been found that in the presence of Fe(III), O2, and an appropriate electron donor (hypoxanthine or NADPH, respectively) glutamine synthetase is also inactivated by either milk xanthine oxidase or Clostridial nicotinate hydroxylase. Inactivation of glutamine synthetase by either of these flavoproteins is greatly stimulated by the presence of electron carrier proteins possessing nonheme-iron-sulfur (NHIS) clusters (i.e., ferredoxin or putidaredoxin) or by the presence of menadione. The inactivation reactions are partially inhibited by free radical scavengers, superoxide dismutase, (SOD), histidine, mannitol, dimethyl sulfoxide, and dimethylthiourea, and are inhibited completely by either Mn(II), EDTA, or catalase. The sensitivity to SOD inhibition is greatly suppressed when the xanthine oxidase system is supplemented with either ferredoxin or redoxin. In the presence of the latter NHIS-proteins (and only when they are present), MFO systems, comprised of either horseradish peroxidase and H2O2 or glucose oxidase, O2, and glucose, can also catalyze the inactivation of GS. The ability of ferredoxin and putidaredoxin to promote oxidation modification of GS by any one of these MFO systems suggests that proteins with NHIS centers may mediate the generation (or stabilization) of highly reactive radical intermediates.

Adenosine Diphosphate↗
PubMed1989

Coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase activities in human liver biopsies with special reference to alcoholic liver disease.

The activities of coproporphyrinogen oxidase, protoporphyrinogen oxidase and ferrochelatase have been assayed in human liver biopsies using recently developed highly sensitive specific enzyme assays. The specific activities (nmol/min/mg protein) in controls were 0.010 +/- 0.003 (mean +/- S.D., n = 11), 0.18 +/- 0.07 (n = 9) and 0.062 +/- 0.022 (n = 8), respectively. The total activities (mumol/min/liver) were determined, using ultrasound to determine liver volumes, and were 2.6 +/- 0.6 (n = 5), 36.6 +/- 13.9 (n = 6) and 14.2 +/- 5.4 (n = 3), respectively. Both specific and total enzyme activities in alcoholics with fatty liver were not significantly different from normal controls. Decreased protoporphyrinogen oxidase activity (0.08 nmol/min/mg protein or 20.2 mumol/min/liver) was found in two patients with variegate porphyria. In a patient with erythrohepatic protoporphyria a reduction of the ferrochelatase activity (0.01 nmol/min/mg protein) was demonstrated.

Biopsy↗
PubMed1979

Monoamine oxidase inhibitors and whole blood, platelet and plasma monoamine oxidase.

1. Whole lysed blood monoamine oxidase activity using benzylamine as substrate, represents an addition of platelet and plasma activity. 2. Enzyme activity measured in whole lysed blood in the presence of 10(-4)M pargyline gave a value equivalent to plasma monoamine oxidase, and by subtraction gives a value for platelet enzyme activity. 3. This method of measuring platelet and plasma monoamine oxidase activities from a single whole blood sample, has the advantage of not requiring physical separation of the blood fraction.

Blood Platelets↗
PubMedDate not supplied

Aldehyde dehydrogenases, aldehyde oxidase and xanthine oxidase from baboon tissues: phenotypic variability and subcellular distribution in liver and brain.

Isoelectric focusing (IEF) and cellulose acetate electrophoresis were used to examine the multiplicity and distribution of aldehyde dehydrogenases (ALDHs), aldehyde oxidase (AOX) and xanthine oxidase (XOX) from tissues of olive and yellow baboons. Five ALDHs were resolved and distinguished on the basis of their differential tissue and subcellular distribution or substrate specificity. Some ALDHs exhibited multiple activity zones. Baboon liver ALDHs were differentially distributed in cytosol (ALDHs II, III and V) and large granular (mitochondrial) fractions (ALDHs I and IV). The major liver ALDHs (I and II) were also broadly distributed in other tissues, as was the major stomach enzyme (ALDH-III). Three brain ALDHs were resolved, which were also differentially distributed between large granular (mitochondrial) (ALDHs I and IV) and cytosolic (ALDH-III) fractions. Electrophoretic variability between individuals was observed for the major liver mitochondrial isozyme (ALDH-I), the major stomach isozyme (ALDH-III) and the minor liver isozymes (ALDHs IV and V). Single forms of AOX and XOX were found in baboon tissue extracts, with the highest activities in liver (AOX) and intestine extracts (XOX). Both oxidases were predominantly localized in the liver soluble fraction.

Aldehyde Dehydrogenase↗
PubMed2002

Towards a new T-fold protein?: the coproporphyrinogen III oxidase sequence matches many structural features from urate oxidase.

Urate oxidase (UOX) and coproporphyrinogen III oxidase (CPO) are two unusual oxidases as they accomplish their catalytic act with no co-factor nor metal ion. They both require molecular oxygen, and lead to hydrogen peroxide in addition to the product. UOX is composed of two contiguous Tunneling-fold domains and CPO appears to be also divided into two structurally equivalent domains. Moreover, each of these putative domains can be coherently aligned on UOX domains. Although their sequences are very distant, we therefore suggest that functional CPO dimer is built around a tunnel, with the substrate sitting above it, on the N- and C-terminal side. This overall model is supported by mutation data and is coherent with the chemical events expected for substrate processing by CPO.

Amino Acid Sequence↗
PubMed1995

Imidazoline/guanidinium binding domains on monoamine oxidases. Relationship to subtypes of imidazoline-binding proteins and tissue-specific interaction of imidazoline ligands with monoamine oxidase B.

Pharmacologically active compounds with an imidazoline and/or guanidinium moiety are recognized with high affinity by a family of membrane-bound proteins collectively known as imidazoline binding sites or imidazoline/guanidinium receptive sites. Two such receptive sites may correspond to imidazoline binding domains identified on the A and B isoforms of monoamine oxidase (MAO), but the detection of monoamine oxidase isoforms in multiple tissues contrasts with the restricted expression of imidazoline-binding proteins. To address these issues, we determined the relationship between monoamine oxidase isoforms and subtypes of imidazoline-binding proteins in human tissues known to express one or both isoforms of MAO. 2-(3-Azido-4-[125I]iodophenoxy)methylimidazoline ([125I]A-ZIPI), a photoaffinity adduct that selectively labels imidazoline-binding proteins, photolabeled an M(r) = approximately 59,000 peptide in liver and an M(r) = approximately 63,000 peptide in placenta, consistent with the M(r) of the MAO isoforms identified by immunoblots in these tissues. The photolabeled species in liver was immunoprecipitated with MAO-B selective antibodies, whereas the photolabeled species in placenta was immunoprecipitated by MAO-A selective antibodies consistent with the isoform of MAO predominantly expressed in these tissues. The imidazoline/guanidinium ligands interact with the enzyme at a site distinct from the substrate recognition domain, and the immunoprecipitated peptides in liver and placenta display distinct ligand recognition properties consistent with those reported for subtypes of imidazoline binding sites. However, the imidazoline binding domain was not detected in platelet membrane preparations containing amounts of MAO-B equivalent to those in the photolabeled liver membranes indicating that recognition of this domain is tissue-restricted. Restricted access to the imidazoline binding domain on platelet MAO-B was not altered by membrane washing with 500 mM KCl or by solubilization and partial purification of the enzyme suggesting that there are distinct subpopulations of MAO. Identification of a binding domain on MAO that recognizes this class of pharmacologically active compounds suggests a novel mechanism for regulation of substrate oxidation/selectivity or that the enzyme may subserve an as yet undefined function.

Affinity Labels↗
PubMed2005

The NADPH oxidase Nox3 constitutively produces superoxide in a p22phox-dependent manner: its regulation by oxidase organizers and activators.

Nox3, a member of the superoxide-producing NADPH oxidase (Nox) family, participates in otoconia formation in mouse inner ears, which is required for perception of balance and gravity. The activity of other Nox enzymes such as gp91(phox)/Nox2 and Nox1 is known to absolutely require both an organizer protein (p47(phox) or Noxo1) andanactivatorprotein (p67(phox) or Noxa1); for the p47(phox)-dependent activation of these oxidases, treatment of cells with stimulants such as phorbol 12-myristate 13-acetate is also indispensable. Here we show that ectopic expression of Nox3 in various types of cells leads to phorbol 12-myristate 13-acetate-independent constitutive production of a substantial amount of superoxide under the conditions where gp91(phox) and Nox1 fail to generate superoxide, i.e. in the absence of the oxidase organizers and activators. Nox3 likely forms a functional complex with p22(phox); Nox3 physically interacts with and stabilizes p22(phox), and the Nox3-dependent superoxide production is totally dependent on p22(phox). The organizers p47(phox) and Noxo1 are capable of enhancing the superoxide production by Nox3 in the absence of the activators, and the enhancement requires the interaction of the organizers with p22(phox), further indicating a link between Nox3 and p22(phox). The p47(phox)-enhanced Nox3 activity is further facilitated by p67(phox) or Noxa1, whereas the activators cancel the Noxo1-induced enhancement. On the other hand, the small GTPase Rac, essential for the gp91(phox) activity, is likely dispensable to the Nox3 system. Thus Nox3 functions together with p22(phox) as an enzyme constitutively producing superoxide, which can be distinctly regulated by combinatorial use of the organizers and activators.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Uncoupling of endothelial nitric oxidase synthase by hypochlorous acid: role of NAD(P)H oxidase-derived superoxide and peroxynitrite.

OBJECTIVE: The aim of the present study is to determine whether hypochlorous acid (HOCl), the major oxidant of leukocyte-derived myeloperoxidase (MPO), oxidizes the zinc-thiolate center of endothelial nitric oxide synthase (eNOS) and uncouples the enzyme. METHODS AND RESULTS: Exposure of purified recombinant eNOS to HOCl (> or = 100 micromol/L) released zinc and disrupted the enzyme-active eNOS dimers. In parallel with increased detections of both O2*- and ONOO-, clinically relevant concentrations of HOCl disrupted eNOS dimers in cultured human umbilical vein endothelial cells (HUVEC) at concentration 10- to 100-fold lower than those required for recombinant eNOS. In HUVEC, HOCl increased the translocation of both p67(phox) and p47(phox) of NAD(P)H oxidase and the phosphorylation of atypical protein kinase C-zeta. Further, genetic or pharmacological inhibition of either NAD(P)H oxidase-derived O2*- or PKC-zeta or NOS abolished the effects of HOCl on eNOS dimers. Consistently, HOCl increased both O2*- and ONOO- and eNOS dimer oxidation in isolated mouse aortas from C57BL/6 but less in those of gp91(phox) knock-out mice. Finally, in human carotid atherosclerotic arteries, eNOS predominantly existed as monomers in parallel with increased staining of both MPO and 3-nitrotyrosine. CONCLUSIONS: We conclude that HOCl uncouples eNOS by ONOO- generated from PKC-zeta-dependent NAD(P)H oxidase.

Animals↗
PubMed1981

[Changes in the state of the histamine--diamine oxidase and serotonin--monoamine oxidase systems and the activity of the sympatho-adrenal system following experimental occlusion of the aortic trifurcation in dogs].

Experiments on 12 dogs have shown that alterations in the intrasystemic parameters of histamine-diamine oxidase, serotonin-monoamine oxidase, adrenaline-noradrenaline and in the intersystemic patterns of adrenaline-histamine indicate the biological adaptation under conditions of embolism of aorta trifurcation induced by 3-hour occlusion. Alterations in the activity of the enzymes studied underlie the adaptational syndrome. During 6-hour occlusions the activity of monoamine oxidase was relatively decreased. Meanwhile the content of serotonin and noradrenaline remained at a high level. These amines might participate in the development of pronounced hypoxic impairments seen in the course of the observation period. It is recommended that adrenoblockers and inhibitors of synthesis of serotonin or serotonin-reactive structures may be used for correction of metabolic disorders.

Acute Disease↗
PubMed1980

[State of serotonin--monoamine oxidase and histamine--diamine oxidase systems in circulating blood in ischemic strokes].

The serotonin-monoamine oxidase and histamine-diamine oxidase systems in the arteria and venous blood of the brain were examined in 65 patients with ischemic cerebral stroke. The examinations have shown that in the acute period of the disease the metabolism of serotonin and histamine is disturbed, the degree and the character of these disturbances depending substantially on the stroke clinical manifestations, process localization and the disease outcome. In infarctions in the large hemispheres without the secondary stem syndrome, the changes of the amine metabolism are determined by the state of the enzymes inactivating them. In patients with the secondary stem syndrome, the monoamine oxidase content in the blood leaving the brain is lowered, the methylation processes are activated, and the histamine level decreased, while the serotonin level is high. In cases of primary affection of the brain stem and the lethal outcome of the disease the blood levels of serotonin and histamine are high. Use of serotonin antagonists in ischemic stroke and antihistaminic drugs in primary affection of the brain stem is substantiated.

Adrenocorticotropic Hormone↗
PubMed1982

Platelet monoamine oxidase and blood plasma benzylamine oxidase activity in cirrhotic patients.

Plasma and platelet benzylamine oxidase activity was tested before and after portacaval shunt in patients with histologically-confirmed cirrhosis of the liver. The level of plasma benzylamine oxidase activity was always higher in cirrhotic patients than in control subjects and was unchanged by the surgical operation. Platelet benzylamine oxidase activity was lower in cirrhotic than in control patients before the surgical operation, and higher afterwards but it returned to the original value at 80 days after surgery.

Benzylamine Oxidase↗
PubMed1995

Cyanide inhibition of porcine kidney diamine oxidase and bovine plasma amine oxidase: evidence for multiple interaction sites.

The interactions of cyanide and phenylhydrazine with porcine kidney diamine oxidase (PKDAO) and bovine plasma amine oxidase (BPAO) (EC 1.4.3.6) have been investigated. Cyanide displays mixed noncompetitive inhibition against amine substrates and also against O2. EPR spectroscopy shows that cyanide binds to an equatorial site on Cu(II) and can be displaced by chloride, which is not an inhibitor, without recovery of activity, indicating that Cu(II)-bound cyanide is not inhibitory. 14CN-. studies have shown that one cyanide in PKDAO and two in BPAO are covalently and irreversibly bound per enzyme dimer at an unknown site, even under conditions where cyanide is not bound to Cu(II). These cyanides have no effect on activity or on binding of phenylhydrazine to the enzymes. Cyanide also binds reversibly to the organic cofactor in both enzymes, presumably as a cyanohydrin, leading to the observed mixed noncompetitive inhibition against substrate. In both enzymes, two phenylhydrazines react per enzyme dimer. The kinetics of phenylhydrazine titration are affected by cyanide, which indicates that phenylhydrazine and cyanide react at the same carbonyl group in the enzymes. The results suggest that inhibition of amine oxidases by cyanide is through a carbonyl reagent and a Cu(I) ligand rather than through a Cu(II) ligand.

Amine Oxidase (Copper-Containing)↗
PubMed1988

Monoclonal glucose-oxidase-anti-glucose-oxidase (GAG) immunosandwich assay for the detection of monoclonal antibodies on routine hematological smears.

A murine monoclonal antibody specific for aspergillus niger glucose oxidase has been prepared and used in an unlabeled antibody bridge technique for the detection of monoclonal antibodies. This procedure--the monoclonal glucose oxidase anti-glucose oxidase (GAG) immunosandwich assay--provides excellent immunocytochemical labeling of routine hematological films in combination with optimal preservation of cellular details. In contrast to conventional immunofluorescence procedures, routine hematological films can be used, and these can be stored before and after the immunolabeling. Compared with other immunoenzyme techniques such as those using alkaline phosphatase or peroxidase, the GAG assay is as sensitive and has the advantage that no problems with endogenous enzyme activity are encountered. The availability of alcohol-resistant disclosing reagents allows for routine hematological counterstaining which provides a very clear visualization of both the immunoreaction and the individual morphology of the blood cells.

Antibodies, Monoclonal↗
PubMed1983

Fatal lipid storage myopathy with deficiency of cytochrome-c-oxidase and carnitine. A contribution to the combined cytochemical-finestructural identification of cytochrome-c-oxidase in longterm frozen muscle.

Two newborn female siblings fell ill with apathy, failure of suckling and a generalized progressive muscular hypotonia. Death occured at the age of 7 weeks, obviously caused by impairment of respiratory musculature. Biochemical studies in one child revealed carnitine deficiency especially in skeletal muscle; hepatic encephalopathy was absent. Both children had a generalized hyperaminoaciduria, an unusual finding in primary carnitine deficiency. Besides fatty metamorphosis of the liver, bilateral hydroureters and tubular calcifications of both kidneys, morphological studies showed a generalized lipid storage myopathy which predominated in Type-I-fibres and was accentuated in the muscles of the neck. Enzymehistochemical electron microscopy in longterm frozen muscle demonstrated that cytochrome-c-oxidase activity was absent not only in myopathic but also in most of the morphological unchanged muscle fibres. Only some fibres and endothelial cells displayed normal activity of mitochondria. Biochemically no cytochrome aa3 (cytochrome-c-oxidase) could be found in skeletal muscle; cytochrome b was almost undetectable. --In newborns with fatal lipid storage myopathy and carnitine deficiency it seems necessary to look for additional defects in the respiratory chain. Enzyme histochemical electron microscopy is a sensitive method in identifying cytochrome-c-oxidase even after a 12 months period of storage.

Carnitine↗