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At least 127 records · Page 7Linked to original sources
PubMed2000

The reactivity of phenolic and non-phenolic residual kraft lignin model compounds with Mn(II)-peroxidase from Lentinula edodes.

Three phenolic model compounds representing bonding patterns of residual kraft lignin were incubated with manganese peroxidase from Lentinula edodes. Extensive degradation of all the phenolic models, mainly occurring via side-chain benzylic oxidation, was observed. Among the tested model compounds the diphenylmethane alpha-5 phenolic model was found to be the most reactive, yielding several products showing oxidation and fragmentation at the bridging position. The non-phenolic 5-5' biphenyl and 5-5' diphenylmethane models were found unreactive.

Biodegradation, Environmental↗
PubMed2003

The role of acidic dissociation of substrate's phenol group in the mechanism of tyrosine phenol-lyase.

pH dependencies of the main kinetic parameters for the reaction of tyrosine phenol-lyase (TPL) with L-tyrosine were studied earlier at pH from 6.0 to 9.5. At this range, L-tyrosine, whose pK(a) for the phenol hydroxyl is 10.5, exists as the zwitterion. It was concluded that zwitterion is the only "active" form for any tyrosine-like substrate. In the present work, we examined pH dependencies for 2-fluorotyrosine, 3-fluorotyrosine, 3,5-difluorotyrosine, 2,5-difluorotyrosine, 2,6-difluorotyrosine, and 3-chlorotyrosine which are more acidic than tyrosine. Respective pK(a)'s are 9.2, 8.7, 7.3, 7.9, 8,35, and 8.3. At higher pH, most of these substrates exist predominantly as anions, having two negative charges at the carboxylic and phenol groups, and one positive charge at the amino group. No decrease of k(cat)/K(m) values attributable to acidic dissociation of the phenol group was found. From comparison of theoretical curves with the experimental data, we conclude that most likely, both zwitterion and anion forms of 3-fluorotyrosine, 3,5-difluorotyrosine, 2,5-difluorotyrosine, 2,6-difluorotyrosine, and 3-chlorotyrosine may be bound and subsequently catalytically transformed by TPL. The reactivities of the two forms are quite comparable. The roles of catalytic groups in the active site, especially Arg381 and Thr-124, are discussed.

Binding Sites↗
PubMed2005

Hydrogen bonding in phenol, water, and phenol-water clusters.

Structure, stability, and hydrogen-bonding interaction in phenol, water, and phenol-water clusters have been investigated using ab initio and density functional theoretical (DFT) methods and using various topological features of electron density. Calculated interaction energies at MP2/6-31G level for clusters with similar hydrogen-bonding pattern reveal that intermolecular interaction in phenol clusters is slightly stronger than in water clusters. However, fusion of phenol and water clusters leads to stability that is akin to that of H(2)O clusters. The presence of hydrogen bond critical points (HBCP) and the values of rho(r(c)) and nabla(2)rho(r(c)) at the HBCPs provide an insight into the nature of closed shell interaction in hydrogen-bonded clusters. It is shown that the calculated values of total rho(r(c)) and nabla(2)rho(r(c)) of all the clusters vary linearly with the interaction energy.

Electrons↗
PubMed2002

Sensitive determination of low molecular mass phenols by liquid chromatography with chemiluminescence detection for the determination of phenol and 4-methylphenol in urine.

A rapid, reliable method for the routine determination of phenol and 4-methylphenol in urine samples by liquid chromatography with peroxyoxalate chemiluminescence detection was developed. Phenols were first cleaned up by passing the sample through a LiChrolut EN sorbent column and then derivatized straightforwardly with dansyl chloride (15 min at room temperature) thanks to the micellar catalytic effect provided by Triton X-100 micelles. The derivatives were successfully separated in 15 min on a C18 analytical column and determined using an integrated derivatization chemiluminescence detection unit based on the bis(2,4,6-trichlorophenyl) oxalate-hydrogen peroxide system. Linear ranges from 3 to 500 microg L(-1), limits of detection at a signal-to-noise ratio of 3 from 0.3 to 0.5 microg L(-1) and relative standard deviations from 2.8 to 4.7% were obtained. The proposed method was applied to the assay of different human urine samples (healthy, smoker and petrol station worker volunteers) and free and total phenol and 4-methylphenol were determined. The proposed method surpasses other chromatographic alternatives for the determination of these phenols in terms of limit of detection and sample requirements for the analysis.

Chromatography, Liquid↗
PubMed2006

In vitro and in vivo analysis of the thyroid system-disrupting activities of brominated phenolic and phenol compounds in Xenopus laevis.

We investigated the effects of the brominated phenolic and phenol compounds, some of which are brominated flame retardants, on the binding of (125)I-3,3',5-L-triiodothyronine ((125)I-T(3)) to purified Xenopus laevis transthyretin (xTTR) and to the ligand-binding domain of X. laevis thyroid hormone receptor beta (xTR LBD), on the induction of a T(3)-responsive reporter gene in a recombinant X. laevis cell line (XL58-TRE-Luc) and on T(3)-induced or spontaneous metamorphosis in X. laevis tadpoles. Of the brominated phenolic and phenol compounds tested, 3,3',5-tribromobisphenol A and 3,3'-dibromobisphenol A were the most potent competitors of (125)I-T(3) binding to xTTR and the xTR LBD, respectively. Structures with a bromine in either ortho positions with respect to the hydroxy group competed more efficiently with T(3) binding to xTTR and the xTR LBD. 3,3',5-Tribromobisphenol A and 3,3',5,5'-tetrabromobisphenol A, at 0.1-1.0 microM, exerted both T(3) agonist and antagonist activities in the T(3)-responsive reporter gene assay. Sera obtained from fetal bovine and bullfrog tadpoles weakened the T(3) agonist and antagonist activities of 3,3',5-tribromobisphenol A, but not the T(3) antagonist activity of o-t-butylphenol, for which xTTR has no significant affinity. The T(3) agonist and antagonist activities of 0.5 microM 3,3',5-tribromobisphenol A were confirmed in the in vivo, short-term gene expression assay in premetamorphic X. laevis tadpoles using endogenous, T(3)-responsive genes as molecular markers. Our results suggest that 3,3',5-tribromobisphenol A affects T(3) binding to xTTR and xTR and that it interferes with the intracellular T(3) signaling pathway.

Animals↗
PubMed1995

Conversion of phenol derivatives to hydroxylated products by phenol hydroxylase from Trichosporon cutaneum. A comparison of regioselectivity and rate of conversion with calculated molecular orbital substrate characteristics.

This study describes the regioselective hydroxylation and the rates of conversion of a series of fluorinated phenol derivatives by phenol hydroxylase from the yeast Trichosporon cutaneum. The natural logarithm of the kcat value for the conversion of the phenolic substrates correlates with the calculated energy of the reactive electrons in the highest occupied molecular orbital of the substrate (r = 0.85). This observation supports the hypothesis that at physiological pH (7.6) and 25 degrees C, in the absence of monovalent anions, the nucleophilic attack of the electrons in the highest occupied molecular orbital of the substrate on the C(4a)-hydroperoxyflavin enzyme intermediate is of major importance in determining the overall rate of catalysis. Results from 19F-NMR analysis of the incubation mixtures demonstrate for phenols with two identical ortho substituents, that the ortho position which becomes preferentially hydroxylated is the one with the highest density of the reactive electrons in the highest occupied molecular orbital. A halogen substituent at a meta position decreases the chances for hydroxylation at the adjacent ortho position further than expected on the basis of the calculated reactivity. This result indicates a contribution of a protein/substrate dipolar interaction, influencing the time-averaged orientation of the substrate with respect to the reactive C(4a)-hydroperoxyflavin intermediate.

Hydroxylation↗
PubMedDate not supplied

[Role of phenol-decomposing microorganisms in the process of phenol destruction in the Black Sea].

The number and species of phenol decomposing microorganisms, as well as the activity of their biochemical oxidation of phenol, were studied in waters of the shelf zone of the Black Sea, from the Danube estuary to Batumi. The number of these microorganisms and their phenol decomposing activity were higher in waters near harbours than in regions outside the anthropogenic activity. These parameters were highest in contaminated waters of the river origin. Most of these phenol decomposing microorganisms belong to the genera Pseudomonas and Bacterium, with the predominance of the species of Bacterium album and Pseudomonas desmolyticum (subspecis Pseudomonas rathionis).

Marine Biology↗
PubMed2003

Comparison of yeast (Candida maltosa) and bacterial (Rhodococcus erythropolis) phenol hydroxylase activity and its properties in the phenolic compounds biodegradation.

Aromatic contaminants of the environment, to which belongs phenol and its derivatives, are toxic and in most of the cases hard to degrade. Removal of these pollutants by biological, gentle and effective way, depends on specific environmental conditions in the locality and on the biodegradation potential of the used microbial population. Closer characterization of the biodegradation and enzyme mechanisms is therefore an essential assumption of the successful implementation of microbes. This paper is focused on comparison of the biodegradation activity between the soil yeast Candida maltosa and bacteria Rhodococcus erythropolis towards various aromatics connected with determination of the first enzyme of the phenol biodegradation pathway: phenol hydroxylase (PH). The effect of substrate type, substrate concentration, growth phase of the microorganisms and presence of humic acids in the cultivation medium, on phenol biodegradation and PH activity are discussed.

Air Pollutants↗
PubMed1997

Assignment of the Vibrations in the Near-Infrared Spectra of Phenol-OH(OD) Derivatives and Application to the Phenol-Pyrazine Complex

The near-infrared spectra (7200-3800 cm-1 ) of seven phenols OH-OD (4-CH3 , H, 4-Cl, 4-Br, 3-Br, 3,4-diCl, 3-5-diCl) are investigated at room temperature in carbon tetrachloride. The mid-infrared spectra of some phenol-OD have also been studied. Beside the first overtone of the nu(OH) stretching vibration, six absorptions disappear upon deuteration. The absorptions are assigned to combinations involving the nu(OH) stretching mode and aromatic ring vibrations, the nu(C-O) mode, or the delta(OH) mode. The anharmonicity and coupling constants are discussed. The isotopic ratio of the nu(OH) stretching fundamentals, of their first overtone, and the ratio of the anharmonicity constants are very insensitive to the nature of the phenol. The stability constants of complexes between phenols and base can be computed from several near-infrared absorptions and this is illustrated for the 3,5-dichlorophenol-pyrazine complex.

Journal Article↗
PubMed1995

Isolation of cDNAs for mouse phenol and bilirubin UDP-glucuronosyltransferases and mapping of the mouse gene for phenol UDP-glucuronosyltransferase (Ugtla1) to chromosome 1 by restriction fragment length variations.

The mouse gene for phenol UDP-glucuronosyltransferase (UDPGT; Ugtla1) was mapped at 42 cM on chromosome 1, a position identical to that of the gene for bilirubin UDPGT (Ugtla1), from linkage analysis of a three-point cross test with Idh-1, En-1, and Ugtla1 as marker genes. The cDNAs for mouse phenol and bilirubin UDPGTs, isolated after amplification by PCR, shared an identical 3'-half region. Our results strongly suggest that mouse bilirubin and phenol UDPGTs are expressed from a single gene and involve alternative splicing events. We also detected duplication of the gene for phenol UDPGT in all mouse strains examined with the exception of MOL-MIT and SUB-SHH.

Animals↗
PubMed1990

Purification and characterization of human liver phenol-sulfating phenol sulfotransferase.

The phenol-sulfating form of phenol sulfotransferase (P-PST) was purified and characterized from human liver cytosol using DEAE-cellulose, Sephacryl S-200, and 3',5'-diphosphoadenosine-agarose affinity chromatography. During the purification procedure, P-PST was resolved from the monoamine-sulfating form of phenol sulfotransferase (M-PST) and dehydroepiandrosterone sulfotransferase, which are also present in human liver cytosol. P-PST activity was purified 560-fold as compared to liver cytosol and the purified enzyme possessed a specific activity of 340 nmol phenol sulfated per minute per milligram protein. Enzymatically active P-PST has an apparent molecular size of 68,000 Da as determined by Sephacryl S-200 chromatography and a subunit molecular weight of 32,000 Da as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that P-PST exists in vivo as a homodimer. Antibodies raised to human platelet M-PST cross-reacted strongly with pure P-PST suggesting the two PSTs are structurally closely related. Two types of P-PST activity have been identified in different human livers by their thermostability and elution during anion-exchange chromatography. Each of the livers examined possessed only one type of P-PST activity. Both types of P-PST were shown to possess the same subunit molecular weight and immunoreactivity, whereas the differences in thermostability of the two P-PST activities appeared to be related to the method of preparation of liver cytosol. Both types of P-PST activity were inhibited to similar extents by incubation with 50 microM N-ethylmaleimide or 5 mM phenylglyoxal. These results suggest that the two types of P-PST in different human livers are very similar and probably represent different allelic forms of the enzyme.

Arylsulfotransferase↗
PubMed1987

Extrahepatic sulfation of phenols. Bovine lung and intestinal phenol sulfotransferases.

Phenol sulfotransferases (PST) from bovine lung and small intestine were purified about 1000-fold. PST from bovine small intestine, similarly as the bovine lung enzyme, catalyzes sulfation of only exogenous phenols. A single thermostable form of PST, active with high concentrations of phenol (Km = 1.43 mM) was found in the small intestine. The effect of divalent cations on the activity of the two phenol sulfotransferases was determined. The molecular weight of the native enzymes was estimated as about 69,000 and subunit molecular weight determined by sodium dodecyl sulfate gel electrophoresis as 35,000. In double immunodiffusion tests the bovine lung PST showed antigenic identity with the bovine small intestine enzyme but complete immunological incompatibility with rat liver sulfotransferase.

Animals↗
PubMed2003

Pemphigus can be induced by topical phenol as well as by foods and drugs that contain phenols or thiols.

Pemphigus is an autoimmune disease that results from the interaction between predisposing genetic factors and exogenous factors, the most common environmental factors being drugs and food. Topical phenol has induced pemphigus in one patient. Drugs and foods that induce pemphigus are divided into three main groups according to their chemical structure: thiols (containing a sulfhydryl group), phenol, nonthiol nonphenol. Thiol and phenol compounds can induce acantholysis in tissue cultures in vitro. The suggested mechanisms for thiol acantholysis include direct biochemical impairment of cell adhesion, protease activation and immunological reaction with the formation of a neoantigen. Possible mechanisms of phenol-induced pemphigus include the induction of IL-1alpha and TNF-alpha release by keratinocytes. These cytokines have been shown to be relevant in the regulation and synthesis of complement and proteases, like plasminogen activator, which has been implicated in the pathogenesis of acantholysis in pemphigus vulgaris. Avoiding exposure of genetically predisposed individuals to these factors is important in treating and preventing this disease.

Journal Article↗
PubMed1995

Structure-activity relationship of phenolic compounds (phenol, pyrocatechol and hydroquinone) on natural lymphocytotoxicity of carp (Cyprinus carpio).

We have tested the effects of phenol and two diphenols (pyrocatechol and hydroquinone) on a non-specific immune response, i.e. the natural cytotoxic activity, of the carp. After a 12-day exposure of fish, at a concentration of 0.1 mg/l, hydroquinone appeared to exert the most immunotoxic effect in vivo. In vitro, after a preincubation of 1 h, phenol (10(-2) M), pyrocatechol (4.25 x 10(-4) M) and hydroquinone (4.25 x 10(-5) M) decreased the natural cytotoxic activity of lymphoid cell suspension. In vivo and in vitro experiments show that hydroquinone is the most toxic compound, whereas diphenols are more toxic than phenol. These results demonstrate that the study of immune systems can reveal the presence of toxic substances with varying degrees of toxicity. Also, the position of a second hydroxic group on the benzonic nucleus seems to influence the compound toxicity.

Animals↗
PubMed1994

Concentrations of phenol, o-cresol, and 2,5-xylenol in the urine of workers employed in the distillation of the phenolic fraction of tar.

Phenol (87.3 mg/l), p-cresol (58.6 mg/l), o-cresol (76.9 mg/l), and 2,5-xylenol (36.7 mg/l) were detected in the urine of workers employed in the distillation of the high temperature phenolic fraction of tar (carbolic oil). The concentrations of these compounds in the urine of non-exposed male workers was 11.7 mg/l, 25.7 mg/l, 68.1 micrograms/l, and 69 micrograms/l respectively. The excretion rates were 4.20 mg/h for phenol, 2.4 mg/h for p-cresol, 3.3 mg/h for o-cresol; and 1.5 mg/h for 2,5-xylenol. The highest concentrations of the mentioned compounds were detected in urine collected between eight and 10 hours from the beginning of exposure. The kinetics of excretion are considered.

Chemical Industry↗
PubMed1981

[Controlled dissecting laboratory trial of different phenol-free-embalming fluids in comparison with phenol-formalin-solution (author's transl)].

Phenyl and formaline, which are contained in a series of embalming fluid formulas, are considered to be disadvantageous in some respect. Different approaches were envisaged in order to minimize risks and to maintain a safe and suitable condition of specimens. Concentrations of phenol and formaldehyde in our customary formula were reduced to 4.1 and 0.82% respectively. Quality of specimen, which had been preserved with this fluid, was compared with that obtained with different phenol-free formulas in standardized dissecting laboratory trials. Best results were registered in bodies preserved with a solution containing ethanol, formaline and glycerine (Tutsch 1975). Quality of specimens preserved with phenol/formaline did not fall short of these to a decisive degree, whereas other solutions (Jores 1913; Neumann 1974) turned out to yield less desirable effects. Successful substitution of preservation with phenol proved to be practicable. Nevertheless high cost of alternative fluids prevented the substitution of our traditional phenol/formaline solution at large scale. In addition to results on comparison of effects of different embalming fluids a survey on our experience with consequent low-pressure injection of bodies and with a new storage system is given.

Anti-Infective Agents, Local↗
PubMed1975

Quantitative determination of phenol in phenolated calamine lotion USP.

A method for the quantitative analysis of phenol in phenolated calamine lotion USP is described. The method is based on spectrophotometrically measuring the color produced by reacting phenol with either ferric chloride or ferric nitrate. Beer's law is followed. The effect of ferric-ion concentration on the sensitivity of the assay method is reported.

Colorimetry↗
PubMed2000

Purification and characterization of hepatic and intestinal phenol sulfotransferase with high affinity for benzo[a]pyrene phenols from channel catfish, Ictalurus punctatus.

Cytosol from channel catfish liver and intestinal mucosa has high sulfotransferase activity with low concentrations of 3-, 7-, or 9-hydroxybenzo[a]pyrene. To further investigate this conjugation pathway, sulfotransferase activity toward 9-hydroxybenzo[a]pyrene was isolated from catfish intestinal and hepatic cytosol by chromatography on anion exchange and PAP-agarose affinity columns. SDS-PAGE of the active fractions showed that one major band with molecular size of about 41,000 Da was isolated from intestine, while two bands of about 41,000 and 31,000 Da were obtained from liver. Antibodies against human phenol-sulfating sulfotransferase cross-reacted strongly with the 41,000-Da bands from liver and intestine, but weakly with the hepatic 31,000-Da protein. N-Terminal sequence information could not be obtained from the pure proteins. Following digestion, an internal sequence of 20 amino acid residues was obtained from the hepatic 41,000-Da protein, which matched a sequence found in several mammalian sulfotransferases. No fish sulfotransferase sequences were available for comparison. The identity of the hepatic 31,000-Da protein was not established. The purified 41,000-Da proteins had very high activities with 3-, 7-, or 9-hydroxybenzo[a]pyrene, with K(m) values in the 40-100 nM range and V(max) 125-300 nmol/min/mg of protein. Substrate inhibition was observed when the concentrations of hydroxylated benzo[a]pyrenes were above 0.5 microM. As well as benzo[a]pyrene phenols, the purified 41,000-Da sulfotransferases catalyzed sulfation of 2-naphthol, 4-nitrophenol, 4-methylumbelliferone, 7-(hydroxymethyl)-12-methylbenz[a]anthracene, dehydroepiandrosterone, estrone, and 17beta-estradiol. Phenolic compounds were the preferred substrates for the purified enzymes.

Amino Acid Sequence↗