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PubMed1985

Differential regulation of hepatic glutathione transferase and glutathione peroxidase activities in the rat.

The effects of the xenobiotics, i.e. butylated hydroxytoluene, beta-naphthoflavone, isosafrole, pregnenolone-16 alpha-carbonitrile, trans-stilbene oxide, 3-methylcholanthrene, phenobarbital, 3,3',4,4'-tetrachlorobiphenyl, 2,2',4,4',5,5'-hexachlorobiphenyl, on rat liver cytosolic glutathione transferase and glutathione peroxidase activities have been investigated. Although the glutathione transferase isozymes (measured by the specific substrates ethacrynic acid and delta 5-androstene-3,17-dione) which have been shown to possess peroxidase activity were significantly increased, little or no increase in peroxidase activity (toward cumene hydroperoxide, tert-butyl hydroperoxide or hydrogen peroxide) was observed. Likewise during a 16-day time course following the administration of Aroclor 1254 or fireMaster BP-6 (each 500 mg/kg, i.p.), potent induction of glutathione transferase activities was seen without any significant increases in peroxidase activities. In fact during the second week of the time course, there were significant decreases in selenium-dependent glutathione peroxidase activity (toward hydrogen peroxide). The inverse regulation of these activities, i.e. the depression of selenium-dependent glutathione peroxidase activity following sustained induction of glutathione transferases, may have direct implications for the toxicity of the polyhalogenated aromatic hydrocarbons.

Animals↗
PubMed1992

Inhibition of mouse glutathione transferases and glutathione peroxidase II by dicumarol and other ligands.

Dicumarol, often used as a specific inhibitor of DT diaphorase (NAD(P)H:(quinone-acceptor) oxidoreductase; EC 1.6.99.2), was found to potently inhibit GSH transferases (EC 2.5.1.18). Dicumarol exhibited an IC50 of 11 microM in inhibiting the conjugation of 1-chloro-2,4-dinitrobenzene (50 microM) by GSH transferase GT-8.7, the major hepatic class mu isoenzyme of CD-1 mice. The activities of GT-8.7 and of the class pi isoenzyme, GT-9.0, toward a carcinogenic substrate, 4-nitroquinoline 1-oxide (100 microM), were inhibited by dicumarol with IC50 values of 14 and 9 microM, respectively. Dicumarol also affected GSH peroxidase II activity, inhibiting the reduction of cumene hydroperoxide by GT-10.6, the predominant class alpha GSH transferase of mouse liver, with an IC50 of 14 microM. GSH peroxidase I (EC 1.11.1.9) and GSH peroxidase II activities were resolved by chromatography of liver and testis cytosols. While inhibiting GSH peroxidase II with IC50 of 9-10 microM, dicumarol did not affect the activity of the selenoenzyme, GSH peroxidase I. Whereas several other non-substrate ligands were more potent inhibitors of 1-chloro-2,4-dinitrobenzene conjugation, dicumarol effectively inhibited GSH transferase and GSH peroxidase II activities in the range of dicumarol concentrations frequently used for detection of DT diaphorase action. These results indicate that physiological consequences resulting from the use of supramicromolar concentrations of dicumarol should not be interpreted in terms of DT diaphorase inhibition alone.

4-Nitroquinoline-1-oxide↗
PubMed1982

Modulation of estrogen-induced peroxidase activity in the rat uterus by thyroid hormones.

The effect of thyroid hormones, iodide, propylthiouracil and other thyroid-active agents on estrogen receptor concentration and on the induction of peroxidase in the immature rat uterus by estradiol (E2) was examined T3 (0.5 mg/Kg) given daily for 6 days produced a large decrease in E2-induced uterine peroxidase but lowered only slightly the concentration of cytosolic or nuclear receptors in this organ. T4 also decreased the effect of E2 on uterine peroxidase induction and the inhibitory action of T3 was observed in thyroidectomized rats. The administration of iodide (10 mM) in the drinking water for 6 days caused a 2-fold increase in estrogen-induced peroxidase in both normal and thyroidectomized immature animals without influencing the estrogen receptor concentration in the uterus. The effect of other thyroid-active agents on serum T3 and T4 levels was also determined. Treatment for 6 days with propylthiouracil (6 mM) increased the concentration of estrogen receptors in the uterus and decreased serum T3 and T4 levels without any effect on uterine peroxidase activity while bromide and perchlorate did not influence these parameters. Possible mechanisms for the inhibitory effects of thyroid hormones on uterine peroxidase induction by E2 are discussed.

Animals↗
PubMed1979

Blood-brain barrier dysfunction to peroxidase after air embolism, aggravated by acute ethanol intoxication.

Ethanol-intoxicated and non-intoxicated rats were injected with horseradish peroxidase and Evan's blue-labelled albumin and given a small air embolus in the right common carotid artery after ligation of the external carotid branch. In both ethanol-intoxicated and non-intoxicated rats, some endothelial cells, mainly in arteries and arterioles, showed a diffuse distribution of peroxidase in the cytoplasm. In some arterioles with a diffuse endothelial distribution of peroxidase there was a detachment of endothelial cells from the vessel wall, with an exposure of the adluminal basement membrane to blood elements. This endothelial detachment was mainly observed in ethanol-intoxicated rats. The vascular basement membranes underlying detached endothelial cells contained peroxidase, both in ethanol-intoxicated and in non-intoxicated rats. There was a considerable leakage of peroxidase via endothelial pinocytotic vesicles into the vascular basement membranes, mainly in arterioles, but also in capillaries and venules of the embolised hemisphere. This transendothelial pinocytotic transport of peroxidase was more prominent in ethanol-intoxicated than in non-intoxicated rats.

Alcoholic Intoxication↗
PubMed1976

Human leukocyte peroxidase: activity of a soluble and membrane-bound enzyme form in normal persons and patients with neuronal ceroid-lipofuscinosis.

Human leukocytes contain a peroxidase fraction soluble in 0.1 M phosphate buffer and an insoluble peroxidase component with 10--15 times higher specific activity which can be extracted by 0.1 M phosphate buffer + 0.2% Triton X-100 + 0.2% sodium taurocholate and sonication. Both enzyme components have been estimated spectrophotometrically with the substrate hydrogen peroxide (final concentration 1 mM) and the hydrogen donor p-phenylenediamine (final concentration 28-55 mM) within the first 60 sec. The pH-optimum of the soluble and membrane-bound leukocyte peroxidase is at pH 7.0 with a second smaller peak at pH 5.5. Using 0.2 M boric acid/0.05 M sodium borate buffer (pH 7.6) instead of phosphate buffer a 40%-50% increase of enzyme activity can be achieved. In two patients with the juvenile form of neuronal ceroid-lipofuscinosis (type Spielmeyer-Vogt) the activity of soluble leukocyte peroxidase was considerably reduced, in one patient with the late infantile form (type Jansky-Bielschowsky) the activity was just below the normal range, and in two patients with the adult form (type Kuf) activity was normal. In all patients the activity of membrane-bound leukocyte peroxidase was not significantly altered. Only one of four heterozygotes for the juvenile type had deficient values of the soluble enzyme. The variability of the peroxidase findings in patients and carriers with neuronal ceroid-lipofuscinosis make it uncertain whether this represents the primary enzymic defect.

Adolescent↗
PubMed1995

Two cationic peroxidases from cell walls of Araucaria araucana seeds.

We have previously reported the purification and partial characterization of two cationic peroxidases from the cell walls of seeds and seedlings of the South American conifer, Araucaria araucana. In this work, we have studied the amino acid composition and NH2-terminal sequences of both enzymes. We also compare the data obtained from these analyses with those reported for other plant peroxidases. The two peroxidases are similar in their amino acid compositions. Both are particularly rich in glycine, which comprises more than 30% of the amino acid residues. The content of serine is also high, ca 17%. The two enzymes are different in their content of arginine, alanine, valine, phenylalanine and threonine. Both peroxidases have identical NH2-terminal sequences, indicating that the two proteins are genetically related and probably are isoforms of the same kind of peroxidase. The amino acid composition and NH2-terminal sequence analyses showed marked differences from the cationic peroxidases from turnip and horseradish.

Amino Acid Sequence↗
PubMed1996

Carbohydrate moieties of three radish peroxidases.

The carbohydrate moieties of two anionic peroxidases, termed A1 and A2, and one cationic peroxidase, named C3, from Korean radish (Raphanus sativus) were studied. For profiling of N-glycans, each peroxidase was treated with peptidyl N-glycosidase F and hydrazine. These peroxidases were more susceptible to hydrazine than to peptidyl N-glycosidase F. When these three peroxidases were subjected to trifluoroacetic acid treatment, mannose, fucose and N-acetylglucosamine were released. Two major N-glycans of peroxidase C3 were isolated and treated with several glycohydrolases. Analysis of digested products of the two major N-glycans on polyacrylamide gel suggested that core-fucosylated trimannosylchitobiose may contain a different linkage from the typical alpha-1,6 of native N-linked oligosaccharide.

Acetylglucosamine↗
PubMed1991

Age-related changes in Cu,Zn superoxide dismutase, Se-dependent and -independent glutathione peroxidase and catalase activities in specific areas of rat brain.

Oxidative injury of tissues involves both accumulation of damage due to persistent oxidative stress and loss of the proper balance of antioxidative enzymes. These events may produce a faster rate of tissue senescence. In this regard, we have assayed the antioxidative enzyme activities (Cu,Zn superoxide dismutase, glutathione peroxidase and catalase), in various areas of rat brain (prefrontal cortex, parietal cortex, hippocampus, hypothalamus, caudate nucleus, mesencephalon and lower brain stem) for the age groups of 3, 6, 12, 24 months. The results obtained show that the levels of antioxidant enzyme activities differed considerably in the various brain parts studied. Furthermore, changes in the specific activities of superoxide dismutase, catalase, and glutathione peroxidase did not follow the same pattern as a function of aging. In particular, in prefrontal cortex and caudate nucleus, superoxide dismutase and glutathione peroxidase activities did not change, while catalase activity decreased. In parietal cortex and mesencephalon, superoxide dismutase and glutathione peroxidase activities increased, but the catalase activity decreased in parietal cortex and did not change in mesencephalon. In lower brain stem, the activities of glutathione peroxidase and catalase decreased in 3-12-month-old rats. The activity of glutathione peroxidase was increased in the hippocampus and was decreased in hypothalamus during aging. In this area the catalase activity was also significantly diminished.

Aging↗
PubMed1978

Hardening of the sea urchin fertilization envelope by peroxidase-catalyzed phenolic coupling of tyrosines.

Within minutes after its elevation from the egg surface, the sea urchin fertilization envelope (FE) becomes "hardened" by a reaction that renders it resistant to agents that solubilize, denature or degrade most proteins. Peroxidase activity is released into the surrounding seawater from Stronglyocentrotus purpuratus eggs during fertilization. Evidence from several sources indicate that the catalytic action of the peroxidase is responsible for hardening the FE through the phenolic coupling of tyrosyl residues of the FE proteins. First, the peroxidase is localized within the hardened FE and within the crystalline FE precursor material released from egg cortical granules during the fertilization reaction. Second, a direct correlation is established between the effectiveness of compounds in inhibiting the cortical granule peroxidase (CGP) and their effectiveness in inhibiting hardening of the FE. Third, the CGP catalyzes the cross-linking of tyrosines in solution, a reaction known to be catalyzed by horseradish peroxidase (HRP). Fourth, acid hydrolysates of hardened FEs contain cross-linked tyrosines that are identified by comparing their chromatographic ultraviolet absorption and fluorescent characteristics to those known for cross-linked tyrosines formed by HRP. Finally, when eggs are fertilized in the presence of 125I, the CGP heavily labels proteins of the FE and of the crystalline FE precursor material released with the enzyme from the cortical granules. The iodide label reflects the localization of the CGP and may reflect the sites of peroxidase-generated tyrosyl phenyl radicals involved in the tyrosine coupling reaction. Maximal iodide labeling occurs during the first 5 min period following fertilization, corresponding to the period of FE hardening.

Animals↗
PubMed1991

The cDNA sequence of a neutral horseradish peroxidase.

A cDNA clone encoding a horseradish (Armoracia rusticana) peroxidase has been isolated and characterized. The cDNA contains 1378 nucleotides excluding the poly(A) tail and the deduced protein contains 327 amino acids which includes a 28 amino acid leader sequence. The predicted amino acid sequence is nine amino acids shorter than the major isoenzyme belonging to the horseradish peroxidase C group (HRP-C) and the sequence shows 53.7% identity with this isoenzyme. The described clone encodes nine cysteines of which eight correspond well with the cysteines found in HRP-C. Five potential N-glycosylation sites with the general sequence Asn-X-Thr/Ser are present in the deduced sequence. Compared to the earlier described HRP-C this is three glycosylation sites less. The shorter sequence and fewer N-glycosylation sites give the native isoenzyme a molecular weight of several thousands less than the horseradish peroxidase C isoenzymes. Comparison with the net charge value of HRP-C indicates that the described cDNA clone encodes a peroxidase which has either the same or a slightly less basic pI value, depending on whether the encoded protein is N-terminally blocked or not. This excludes the possibility that HRP-n could belong to either the HRP-A, -D or -E groups. The low sequence identity (53.7%) with HRP-C indicates that the described clone does not belong to the HRP-C isoenzyme group and comparison of the total amino acid composition with the HRP-B group does not place the described clone within this isoenzyme group. Our conclusion is that the described cDNA clone encodes a neutral horseradish peroxidase which belongs to a new, not earlier described, horseradish peroxidase group.

Amino Acid Sequence↗
PubMed1991

Structural and functional features of Pseudomonas cytochrome c peroxidase.

The secondary structure of Pseudomonas cytochrome c peroxidase (ferrocytochrome c: hydrogen-peroxide oxidoreductase, EC 1.11.1.5) has been predicted from the established amino acid sequence of the enzyme using a Chou-Fasman-type algorithm. The amount of alpha-helicity thus obtained is in agreement with previously obtained results based on circular dichroic measurements at far UV. The two heme c moieties of the enzyme have earlier been shown to have widely different characteristics, e.g., the redox potentials of the hemes differ with about 600 mV, and carry out different functions in the enzyme molecule. The structural comparisons made in this study enlighten the observed functional differences. The first heme in the polypeptide chain, heme 1, has in its environment a folding pattern generally encountered in cytochromes. In the region of the sixth ligand, however, profound differences are noted. The cytochromal methionine has been replaced by a lysine with a concomitant lowering of redox-potential thus making peroxidatic activity possible. Around heme 2, extra amino acid residues have been added to the peroxidase as compared with Rhodospirillum molischianum cytochrome c2 core structure in the 20's loop. After completion of the cytochromal fold around heme 2 an additional tail consisting of 25 residues is linked. This tail shows no stabilizing elements of secondary structure, but contains a strongly hydrophobic segment which suggests a possible membrane contact site of this extrinsic membrane protein. Heme 2 is concluded to have a cytochromal function in the molecule. To further elucidate the functional properties of the enzyme, a noncovalent two-fragment complex was produced by specific cleavage of the peroxidase by Pseudomonas elastase. The complex was studied with respect to its properties to the native enzyme. The two-fragment complex of Pseudomonas peroxidase retains the overall conformation of the native enzyme showing, however, no heme-heme interaction. Thus, a comparison of the properties of the native enzyme with those of the two-fragment complex permitted some conclusions to be drawn on the structure of the enzyme as well as the mechanism of heme-heme interaction. From the present results we conclude that the two distal heme surfaces in the peroxidase are oriented toward each other. This structural arrangement allows an inter-heme communication in the enzyme molecule and it also forms the structural basis for the enzyme mechanism. The structural comparisons also give insight into the evolution of an ancestral cytochrome c into an efficient peroxidase that has a versatile control mechanism in heme-heme interaction.

Amino Acid Sequence↗
PubMed1992

Oxidation of hydroquinone by both cellular and extracellular grapevine peroxidase fractions.

The oxidation of hydroquinone by two peroxidase (EC 1.11.1.7) fractions obtained from the cells and spent medium of cell cultures of grapevine (Vitis vinifera cv Monastrell) has been studied, and their comparative efficacy (kcat/KM ratio) studied in both the H2O2-consuming and hydroquinone-consuming reactions. While the efficacy in the H2O2-consuming reaction is practically identical for both enzyme fractions, the cellular peroxidase has five-fold more efficacy in the hydroquinone-consuming reaction than the peroxidase located in the spent medium. Screening of cellular peroxidases capable of oxidizing hydroquinone on polyacrylamide gels, by means of a staining reaction based on the nucleophilic attack of 4-aminoantipyrine on p-benzoquinone in acidic media, reveals that all the cellular peroxidase isoenzymes are capable of oxidizing hydroquinone, probably yielding a quinone-diimine as a product of the staining reaction. Since isoperoxidases found in cellular fractions are also present in the spent medium, the values found for the different efficacies in the hydroquinone-consuming reaction must be considered as the results of the different proportions in which each peroxidase isoenzyme was found in the two fractions. The localization of a benzoquinone-generating system of high efficacy inside the plant cell, and probably located in vacuoles, is discussed with respect to the harmful role which the quinone/semiquinone pair might play in cell death, as part of the hypersensitive response expressed within the mechanism of plant disease resistance.

Ampyrone↗
PubMed1981

beta-Adrenergic receptors stimulated peroxidase secretion from rat lacrimal gland.

Incubation of rat extraorbital lacrimal gland slices with the beta-agonist isoproterenol caused peroxidase secretion but no K+ release. The peroxidase secretion was inhibited by propranolol. Addition of dibutyryl cyclic AMP or adenosine 3'5'-cyclic phosphorothioate to lacrimal slices produced peroxidase secretion at a higher rate than that obtained with optimal concentration of isoproterenol. Methyl isobutylxanthine is also a strong stimulator of peroxidase secretion. Peroxidase activity was determined by a modified sensitive guaiacol method. Membrane fraction of lacrimal cells was shown to contain an isoproterenol-stimulated adenylate cyclase activity. It is therefore suggested that there is a beta-adrenergic receptor in the rat lacrimal gland and that its stimulation causes activation of an adenylate cyclase which leads to peroxidase secretion.

1-Methyl-3-isobutylxanthine↗
PubMed1985

The selenoenzyme phospholipid hydroperoxide glutathione peroxidase.

The reduction of membrane-bound hydroperoxides is a major factor acting against lipid peroxidation in living systems. This paper presents the characterization of the previously described 'peroxidation-inhibiting protein' as a 'phospholipid hydroperoxide glutathione peroxidase'. The enzyme is a monomer of 23 kDa (SDS-polyacrylamide gel electrophoresis). It contains one gatom Se/22 000 g protein. Se is in the selenol form, as indicated by the inactivation experiments in the presence of iodoacetate under reducing conditions. The glutathione peroxidase activity is essentially the same on different phospholipids enzymatically hydroperoxidized by the use of soybean lipoxidase (EC 1.13.11.12) in the presence of deoxycholate. The kinetic data are compatible with a tert-uni ping-pong mechanism, as in the case of the 'classical' glutathione peroxidase (EC 1.11.1.9). The second-order rate constants (K1) for the reaction of the enzyme with the hydroperoxide substrates indicate that, while H2O2 is reduced faster by the glutathione peroxidase, linoleic acid hydroperoxide is reduced faster by the present enzyme. Moreover, the phospholipid hydroperoxides are reduced only by the latter. The dramatic stimulation exerted by Triton X-100 on the reduction of the phospholipid hydroperoxides suggests that this enzyme has an 'interfacial' character. The similarity of amino acid composition, Se content and kinetic mechanism, relative to the difference in substrate specificity, indicates that the two enzymes 'classical' glutathione peroxidase and phospholipid hydroperoxide glutathione peroxidase are in some way related. The latter is apparently specialized for lipophylic, interfacial substrates.

Animals↗
PubMed1996

Immunocytochemical localization of seleno-glutathione peroxidase in the adult mouse brain.

Cytoplasmic seleno-glutathione peroxidase, by reducing hydrogen peroxide and fatty acid hydroperoxides, may be a major protective enzyme against oxidative damage in the brain. Oxidative damage is strongly suspected to contribute to normal aging and neurodegenerative process of Alzheimer's and Parkinson's diseases. We report here an immunocytochemical analysis of the localization of glutathione peroxidase in the adult mouse brain, carried out with an affinity-purified polyclonal antibody. Most of the brain areas analysed showed weak to strong glutathione peroxidase immunoreactivity, expressed in both neurons and glial cells. The strongest immunoreactivity was found in the reticular thalamic and red nuclei. Highly immunoreactive neurons were observed in the cerebral cortex (layer II), the CA1, dentate gyrus and pontine nucleus. Other regions, such as the caudate-putamen, septum nuclei, diagonal band of Broca, hippocampus, thalamus and hypothalamus, showed moderate staining. This study provides original information about the wide distribution of glutathione peroxidase in the mouse brain. Double-staining experiments indicated that specific subsets of cholinergic neurons in septal and diagonal band nuclei were negative for this antigen. Similarly, many dopaminergic neurons of the substantia nigra pars compacta expressed low levels of glutathione peroxidase antigen, in contrast to the ventral tegmental area, wherein most catecholaminergic cells were strongly positive. A lack of glutathione peroxidase in subsets of dopaminergic or cholinergic neurons may thus confer a relative sensitivity of these cells to oxidative injury of various origins, including catecholamine oxidation, neurotoxins and excitotoxicity.

Animals↗
PubMedDate not supplied

Mechanisms of the stimulation of rat uterine peroxidase activity by methoxychlor.

Methoxychlor (MXC) has adverse effects on fertility and rat uteri via its active metabolite HPTE (2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane). Uterine peroxidase, a marker of estrogen action, was used to probe potential mechanisms of MXC's adverse effects. Specifically, our objective was to compare the regulation of the effects of estrogen and MXC on uterine peroxidase. Immature female rats were treated with MXC (250 mg/kg; gavage) 24 h prior to the measurement of uterine peroxidase activity, with or without concurrent treatment with actinomycin D, cycloheximide, progesterone, or tamoxifen. MXC alone produced an increase in peroxidase activity. The prior and/or concurrent treatment with the compounds listed blocked the MXC-induced stimulation of peroxidase. These data show similarities between the mechanisms of estrogen MXC action. Both estrogen and MXC act to stimulate uterine peroxidase activity via increased RNA and protein synthesis and this stimulation can be blocked by progesterone and tamoxifen.

Animals↗
PubMed2005

Partially purified bitter gourd (Momordica charantia) peroxidase catalyzed decolorization of textile and other industrially important dyes.

The aim of this study was to evaluate the enzymatic action of partially purified bitter gourd peroxidase for the degradation/decolorization of complex aromatic structures. Twenty-one dyes, with a wide spectrum of chemical groups, currently being used by the textile and other important industries have been selected for the study. Here, for the first time we have shown peroxidases from Momordica charantia (300 EU/gm of vegetable) to be highly effective in decolorizing industrially important dyes. Dye solutions, containing 50-200 mg dye/l, were used for the treatment with bitter gourd peroxidase (specific activity of 99.0 EU/mg protein). M. charantia peroxidases were able to decolorize most of the textile dyes by forming insoluble precipitate. When the textile dyes were treated with increasing concentration of enzyme, it was observed that greater fraction of the color was removed but four out of eight reactive dyes were recalcitrant to decolorization by bitter gourd peroxidase. Step-wise addition of enzyme to the decolorizing reaction mixture at the interval of 1h further enhanced the dye decolorization. The rate of decolorization was enhanced when the dyes were incubated with fixed quantity of enzyme for increasing times. Decolorization of non-textile dyes resulted in the degradation and removal of dyes from the solution without any precipitate formation. Decolorization rate was drastically increased when the textile and other industrially important non-textile dyes were treated with bitter gourd peroxidase in presence of 1.0 mM 1-hydroxybenzotriazole. Complex mixtures of dyes were prepared by taking three to four reactive textile and non-textile dyes in equal proportions. Each mixture was decolorized by more than 80% when treated with the enzyme in presence of 1.0 mM 1-hydroxybenzotriazole. Our data suggest that the peroxidase/mediator system is an effective biocatalyst for the treatment of effluents containing recalcitrant dyes from textile, dye manufacturing, dyeing and printing industries.

Color↗
PubMed2005

The nop gene from Phanerochaete chrysosporium encodes a peroxidase with novel structural features.

Inspection of the genome of the ligninolytic basidiomycete Phanerochaete chrysosporium revealed an unusual peroxidase_like sequence. The corresponding full length cDNA was sequenced and an archetypal secretion signal predicted. The deduced mature protein (NoP, novel peroxidase) contains 295 aa residues and is therefore considerably shorter than other Class II (fungal) peroxidases, such as lignin peroxidases and manganese peroxidases. Comparative modeling of NoP was conducted using the crystal structures of Coprinus cinereus and Arthromyces ramosus peroxidases as templates. The model was validated by molecular dynamics and showed several novel structural features. In particular, NoP has only three disulfide bridges and tryptophan replaces the distal phenylalanine within the heme pocket.

Amino Acid Sequence↗