Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.11.1.7 (peroxidase)
 65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new enzyme which catalyzes the oxidation of the side chain of tryptophan and other indole derivatives, has been purified to apparent homogeneity from Pseudomonas and crystallized. The overall purification was about 25-fold with a yield of 4.5%. The purified enzyme was apparently homogeneous as judged by polyacrylamide gel electrophoresis. The molecular weight estimated by gel filtration was approximately 280,000 and sedimentation coefficient (S20,w) was 11 by sucrose density gradient ultracentrifugation. The absorption spectra indicated that the enzyme was a hemoprotein. The purified enzyme was shown to catalyze the reaction in which 1 mol each of NH3 and CO2 was formed at the expense of 1 mol each of L-tryptophan and molecular oxygen. Neither peroxidase nor catalase activity was detected in the purified enzyme and no formation of H2O2 was observed during the enzyme reaction. The product(s) of the reaction was unstable but was converted to and was identified as its stable quinoxaline derivative, 2-(3-indolyl)quinoxaline, in the presence of o-phenylenediamine. These results indicate that the product of the reaction was 3-indolylglycoaldehyde or 3-indolylglyoxal. A variety of other indole derivatives such as D-tryptophan, 5-hydroxyl-L-tryptophan, tryptamine, serotonin, melatonin, N-acetyl-L-tryptophan, N-acetyl-L-tryptophanamide, 3-indoleacetamide, 3-indolelactic acid, 3-indolepropionic acid, 3-indoleethanol, and skatole were also substrates.
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PMID:Crystalline hemoprotein from Pseudomonas that catalyzes oxidation of side chain of tryptophan and other indole derivatives. 1 95

The effects of K2PtCl4, cis-Pt(NH3)2Cl2, and trans-Pt(NH3)2Cl2 on the activities of glyceraldehyde-3-phosphate dehydrogenase, glucose-6-phosphate dehydrogenase, dihydrofolate reductase, fructose-1,6-bisphosphate aldolase, catalase, tyrosinase, and peroxidase have been investigated. All of the enzymes which are thought to have essential sulfhydryl groups (glyceraldehyde-3-phosphate dehydrogenase, aldolase, and glucose-6-phosphate dehydrogenase) were significantly inhibited by K2PtCl4. The other four enzymes studied are not known to have essential sulfhydryl groups, and were not significantly affected by the Pt compounds under the conditions employed. Glyceraldehyde-3-phosphate dehydrogenase was the only enzyme inhibited by all three Pt compounds tested, with K2PtCl4 being the most effective and cis-Pt(NH3)2Cl2 the least effective inhibitor. Semilogarithmic plots of residual activity versus inhibition time indicated that the inhibition reactions were not simple first-order processes, except for the inhibition of glucose-6-phosphate dehydrogenase by K2PtCl4 which appeared to be first-order with respect to enzyme concentration.
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PMID:The effects of platinum complexes on seven enzymes. 11 85

The chlorination of dipeptides by the myeloperoxidase/H2O2/Cl- system takes place at the N-terminal amino group, whereas no chlorination of the amide nitrogen of the peptide bond can be observed. The N-terminal amino group is chlorinated to N-monochloroamine or/and N-dichloroamine. N-Monochloropeptides were the main products at higher pH values, at lower pH at mixture of N-monochloropeptides and N-dichloropeptides was formed owing to the dismutation of N-monochloroamine to N-dichloroamine. N-Monochloropeptides decompose, yielding NH3 and the corresponding N-(2-oxoacyl)amino acids. N-Dichlorodipeptides decompose faster but to nitriles and the free C-terminal amino acids. N-Dichloroglycyl-amino acid decomposes through a relatively stable intermediate (cyano-formylamino acid) to hydrogen cyanide, cyanogen chloride and the free C-terminal amino acid. Insulin chlorination also yields N-terminal glycyl and phenylalanyl N-monochloro derivatives, which deaminate to glyoxylyl and phenylpyruvyl residues.
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PMID:N-(2-Oxoacyl)amino acids and nitriles as final products of dipeptide chlorination mediated by the myeloperoxidase/H2O2/Cl- system. 21 10

A simple and relatively sensitive procedure was developed for determination of L-lysine at 3-30 mmole/L concentration. The procedure does not involve the carcinogenic compound o-dianisidine. L-lysine alpha-oxidase catalyzed oxidative deamination of L-lysine with O2 consumption and formation of H2O2, NH3 and alpha-keto-epsilon-aminocaproic acid. Horseradish peroxidase and a non-carcinogenic compound 3,3,5,5'-tetramethylbenzidine dihydrochloride as an electron donor were used in determination of H2O2 formed. The procedure developed enabled also to measure the L-lysine alpha-oxidase activity at the enzyme concentrations of 10-500 ng/ml. The only limitation of the procedure is relatively low pH-values of the reaction medium.
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PMID:[A spectrophotometric method for determining the concentration of L-lysine using L-lysine-alpha-oxidase from Trichoderma sp. and 3,3',5,5'-tetramethylbenzidene dihydrochloride]. 194 95

Myocardial ischemia is characterized by the liberation of adenosine and by complement-mediated inflammation. We have reported that amidated C3, formed when ammonia (NH3) disrupts the thiolester bond of C3, serves as an alternative pathway convertase, generates C5b-9, and stimulates phagocytic oxidative metabolism. We investigated whether the deamination of adenosine by adenosine deaminase in hematopoietic cells might liberate sufficient ammonia to form amidated C3 and thereby trigger complement-mediated inflammation at ischemic sites. In the presence of 4 mM adenosine, NH3 production per erythrocyte (RBC) was equal to that per neutrophil (PMN) (3.3 X 10(-15) mol/cell per h). Because RBC outnumber PMN in normal blood by a thousandfold, RBC are the major source of NH3 production in the presence of adenosine. NH3 production derived only from the deamination of adenosine by the enzyme adenosine deaminase and was abolished by 0.4 microM 2'-deoxycoformycin, a specific inhibitor of adenosine deaminase. When purified human C3 was incubated with 5 X 10(8) human RBC in the presence of adenosine, disruption of the C3 thiolester increased more than twofold over that measured in C3 incubated with buffer, or in C3 incubated with RBC (P less than 0.05). The formation of amidated C3 was abolished by the preincubation of RBC with 2'-deoxycoformycin (P less than 0.001). Amidated C3 elicited statistically significant release of superoxide, myeloperoxidase, and lactoferrin from PMN. Thus, the formation of amidated C3 by RBC deamination of adenosine triggers a cascade of complement-mediated inflammatory reactions.
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PMID:The erythrocyte as instigator of inflammation. Generation of amidated C3 by erythrocyte adenosine deaminase. 278 75

We identify the cyanogenic substrate for horseradish peroxidase (HRP) as a conjugated enamine and explore this unusual reaction using alpha-aminocinnamate (RH) as follows. 1) HRP catalyzes the oxidation of RH by O2 (and its peroxidation by H2O2 to form R-R) to produce, simultaneously, CN- and benzaldehyde cyanohydrin. 2) RH is transient and must be generated in situ. The properties of the cyanogenic reaction of HRP are independent of the method of preparation of RH (whether this be condensation of NH3 with phenylpyruvate, enzymatic hydrolysis of glycyldehydrophenylalanine, or oxidation of L-phenylalanine by L-amino acid oxidase). 3) The oxidation of RH is a free radical chain reaction initiated by HRP Compounds I and II (I (or II) + RH----R. + II (or HRP], propagated by RO2. (R. + O2----RO2., RO2. + RH----R. + RO2H), and terminated by recombination reactions such as 2R.----R2 and RO2.----R' + HO2. followed by R. + HO2.----RH + O2. KMnO4 and K3Fe(CN)6 can substitute for HRP. 4) The proximal precursor of CN- and cyanohydrin is postulated to be RO2H (phi-CH(-O2H)-CCO2-(= NH]. These results explain why cyanide is generated from the synergistic action of HRP and L-amino acid oxidase on aromatic L-amino acids and O2 and suggest that the requirement for a beta-aryl substituent on the enamine originates in the reaction of RH with HRP, or of R with O2, rather than the imine/enamine tautomerization of the L-amino acid oxidase product.
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PMID:The cyanogenic substrate for horseradish peroxidase is a conjugated enamine. 311 Jan 55

Conditions were sought to increase the yield of HCN from L-histidine incubated with L-amino acid oxidase (L-amino acid:oxygen oxidoreductase (deaminating), EC 1.4.3.2) from snake venom, and horseradish peroxidase (donor:hydrogen-peroxide oxidoreductase, EC 1.11.1.7). Small amounts of histidine and high buffer concentrations favored high HCN yields, which reached a maximum of 72%. Imidazole 4-aldehyde and imidazole 4-carboxylic acid were identified among the reaction products, together with CO2, NH3, H2O2 and imidazole acetic acid. The CO2 formed was equal to the histidine oxidized, and to the sum of NH3 plus HCN formed. The production of HCN was associated with an increased O2 uptake, which was established from the beginning of the reaction, with no apparent lag and ranged from 1.2 to 1.6 mumol extra O2 taken up/mumol HCN formed. The system was inhibited by catalase, but added superoxide dismutase caused a small stimulation of both HCN production and O2 consumption, and a larger stimulation of H2O2 accumulation. Added hydroxylamine was cooxidized to nitrite in an amount equimolar with the HCN formed. This nitrite formation was inhibited by superoxide dismutase. The facts could be interpreted in terms of superoxide anion formation during the HCN-producing reaction. cytochrome c, heme, or ferricyanide could be substituted for peroxidase, but were less effective. The initial rates of HCN formation from phenylalanine, tyrosine and tryptophan were higher, but the eventual yields of HCN from these amino acids were lower than those from histidine.
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PMID:The formation of hydrogen cyanide from histidine in the presence of amino acid oxidase and peroxidase. 735 Sep 10

The structure-activity relationships for the interactions of a number of sulfhydryl compounds on the transformation of (Z)-3-(4-bromophenyl)-3-(3-pyridyl)allylamine (CPP 200) by an MPO-H2O2-Cl-(-)system at pH 5.25 have been studied. It was found that the inhibitory effect of the thiol group was strongly dependent on the presence of an electron-withdrawing NH3(+)-group in the molecule. Also, the acid-base properties of the thiolic compounds were involved in the inhibitory mechanisms.
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PMID:Influence of thiols on the chlorinating effect of a myeloperoxidase system. 776 41

The luminal surface of mammalian bladder is exposed to urine with a composition widely different from that of plasma that bathes the basolateral surface of epithelium. Therefore we predict that the bladder permeability barrier, which is likely located in the apical membrane (AM), will exhibit low permeabilities to water, urea, NH3, H+, and small nonelectrolytes. AM surface area increases as the bladder fills with urine and decreases during emptying, a process that involves cyclical endocytosis and reinsertion of membrane from a pool of AM endosomes (AME). Rigid-appearing plaques composed of three proteins, uroplakins, have been identified and occupy 70-90% of AM surface area. To determine permeability properties of the AM permeability barrier, we purified AME and measured their permeabilities. Rabbit urinary bladders were removed, and their apical surface was exposed to carboxyfluorescein (CF) or horseradish peroxidase (HRP). Exposure to hypotonic and then isotonic basolateral solutions induced endocytosis of luminal CF or HRP into AME. Electron microscopy of bladders after this treatment revealed HRP entrapped within AME bordered by plaques. AME were purified by differential and sucrose-gradient centrifugation, and CF-containing AME were purified 17.0 +/- 3-fold (SD) with respect to homogenate. Analysis of purified AME by flow cytometry showed that > 95% of vesicles contained CF entrapped from luminal solution and were selectively labeled with anti-uroplakin antibody. AME osmotic water permeability averaged 2.3 +/- 0.66 x 10(-4) cm/s and exhibited a high activation energy, indicating that AM contains no water channels. Permeability to urea and NH3 averaged 7.8 +/- 3.7 x 10(-7) and 1.5 +/- 0.3 x 10(-3) cm/s, respectively, which are exceptionally low and similar to permeabilities of other water-tight membranes, including toad urinary bladder and gastric mucosa. AME behaved as a single population in all permeability studies, which will permit future characterization of protein and lipid structure responsible for these unique permeability properties.
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PMID:Permeability properties of the mammalian bladder apical membrane. 797 9

This study addresses the mechanism of covalent aggregation of human Cu,Zn-superoxide dismutase (hSOD1WT) induced by bicarbonate (HCO3-)-mediated peroxidase activity. Higher molecular weight species (apparent dimers and trimers) of hSOD1WT were formed from incubation mixtures containing hSOD1WT, H2O2, and HCO3-. HCO3--dependent peroxidase activity and covalent aggregation of hSOD1WT were mimicked by UV photolysis of hSOD1-WT in the presence of a [Co(NH3)5CO3]+ complex that generates the carbonate radical anion (CO3.). Human SOD1WT has but one aromatic residue, a tryptophan residue (Trp-32) on the surface of the protein. Substitution of Trp-32 with phenylalanine produced a mutant (hSOD1W32F) that exhibits HCO3--dependent peroxidase activity similar to wild-type enzyme. However, unlike hSOD1WT, incubations containing hSOD1W32F,H2O2, and HCO3-did not result in covalent aggregation of SOD1. These findings indicate that Trp-32 is crucial for CO3.-induced covalent aggregation of hSOD1WT. Spin-trapping results revealed the formation of the Trp-32 radical from hSOD1WT, but not from hSOD1W32F. Spin traps also inhibited the covalent aggregation of hSOD1WT. Fluorescence experiments revealed that Trp-32 was further oxidized by CO3., forming kynurenine-type products in the presence of oxygen. Molecular oxygen was needed for HCO3-/H2O2-dependent aggregation of hSOD1WT, implicating a role for a Trp-32-dependent peroxidative reaction in the covalent aggregation of hSOD1WT. Taken together, these results indicate that Trp-32 oxidation is crucial for covalent aggregation of hSOD1. Implications of HCO3--dependent SOD1 peroxidase activity in amyotrophic lateral sclerosis disease are discussed.
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PMID:Bicarbonate-dependent peroxidase activity of human Cu,Zn-superoxide dismutase induces covalent aggregation of protein: intermediacy of tryptophan-derived oxidation products. 1268 60


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