RESUMO
The use of saliva as a biological sample has many advantages, being especially relevant in pigs where the blood collection is highly stressful and painful, both for the animal and the staff in charge of the sampling. Currently one of the main uses of saliva is for diagnosis and detection of infectious diseases, but the saliva can also be used to measure biomarkers that can provide information of stress, inflammation, immune response and redox homeostasis. This review will be focused on the analytes that can be used for such evaluations. Emphasis will be given in providing data of practical use about their physiological basis, how they can be measured, and their interpretation. In addition, some general rules regarding sampling and saliva storage are provided and the concept of sialochemistry will be addressed. There is still a need for more data and knowledge for most of these biomarkers to optimize their use, application, and interpretation. However, this review provides updated data to illustrate that besides the detection of pathogens in saliva, additional interesting applicative information regarding pigs´ welfare and health can be obtained from this fluid. Information that can potentially be applied to other animal species as well as to humans.
Assuntos
Saliva , Doenças dos Suínos , Animais , Biomarcadores , Homeostase , Sistema Imunitário , Inflamação/diagnóstico , Inflamação/veterinária , Oxirredução , Saliva/metabolismo , Suínos , Doenças dos Suínos/diagnósticoRESUMO
The biological pretreatment of lignocellulosic biomass for the production of bioethanol is an environmentally friendly alternative to the most frequently used process, steam explosion (SE). However, this pretreatment can still not be industrially implemented due to long incubation times. The main objective of this work was to test the viability of and optimise the biological pretreatment of lignocellulosic biomass, which uses ligninolytic fungi (Pleurotus eryngii and Irpex lacteus) in a solid-state fermentation of sterilised wheat straw complemented with a mild alkali treatment. In this study, the most important parameters of the mechanical and thermal substrate conditioning processes and the most important parameters of the fungal fermentation process were optimised to improve sugar recovery. The largest digestibilities were achieved with fermentation with I. lacteus under optimised conditions, under which cellulose and hemicellulose digestibility increased after 21 days of pretreatment from 16 to 100 % and 12 to 87 %, respectively. The maximum glucose yield (84 %) of cellulose available in raw material was obtained after only 14 days of pretreatment with an overall ethanol yield of 74 % of the theoretical value, which is similar to that reached with SE.
Assuntos
Biomassa , Etanol/metabolismo , Glucose/metabolismo , Lignina , Pleurotus/crescimento & desenvolvimento , Triticum/química , Lignina/química , Lignina/metabolismoRESUMO
The aim of this study was to validate automated methods to measure iron (Fe), zinc (Zn), copper (Cu) and ferritin in pig saliva samples. A complete analytical validation was performed of all assays. In addition, these methods were applied to saliva of Fe supplemented (n = 22) and non-supplemented (n = 20) piglets. All assays were able to measure these biomarkers in pig saliva with adequate precision, accuracy and high sensitivity and, in case of trace elements without needing a deproteinization pre-process. The group of piglets supplemented with Fe presented significantly higher levels of ferritin and Zn in saliva. In conclusion, the automated assays evaluated were able to measure Fe, Zn, Cu and ferritin in saliva of pigs, and in case of trace elements, they have the advantage of not needing a deproteinization pre-treatment and thus these analytes can be measured in a simple and fast manner.
Assuntos
Oligoelementos , Suínos , Animais , Oligoelementos/metabolismo , Ferro/metabolismo , Saliva/metabolismo , Zinco/metabolismo , FerritinasRESUMO
D-dimer is a peptide found in serum and is derived from the degradation of blood clots. Even though it has been analysed in human saliva, D-dimer has not been previously evaluated in the saliva of any veterinary species, and its source and role remain unknown. The objectives of this research were firstly, to validate the use of an automated method for the measurement of D-dimer in porcine saliva, and secondly, to evaluate whether D-dimer concentration changes in pig saliva after an acute stress stimulus. For this purpose, a complete analytical validation of a commercially-available immunoturbidimetric assay was carried out. In addition, an experimental acute stress model was induced in 11 pigs based on a technique involving restraint by nose-snare immobilisation for 1 min. Saliva samples were subsequently collected at different times and D-dimer, salivary alpha-amylase (sAA) and cortisol were assessed in order to evaluate changes in its concentrations after the stress induction. The D-dimer automated assay showed adequate reproducibility and sensitivity, with coefficients of variation below 10% and a limit of quantification of 0.167 µg/mL fibrinogen equivalent units (FEU). It also showed a high accuracy, determined by linearity under dilution and recovery tests. In the stress model, a significant increase (P < 0.05) in salivary D-dimer 15 min after the stress stimulus and a positive correlation between D-dimer and sAA (r = 0.51; P < 0.001) were observed. These results indicate that D-dimer can be measured in porcine saliva with an automated method and suggest that its concentration can be influenced by stressful conditions.
Assuntos
Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Saliva/metabolismo , Estresse Fisiológico , Doenças dos Suínos/metabolismo , Animais , Bioensaio/veterinária , Biomarcadores/metabolismo , Feminino , Masculino , Reprodutibilidade dos Testes , Restrição Física/veterinária , SuínosRESUMO
The characteristics of neutral cholesteryl ester hydrolase activities found in the microsomal and cytosolic subcellular fractions of rat lactating mammary tissue were investigated. The enzymes were assayed using cholesteryl oleate dispersed as a mixed micelle with phosphatidylcholine and sodium taurocholate (molar ratio 1:4:2) as substrate. This method gave activities approx. 20-fold higher than those seen when cholesteryl oleate was added in ethanol. Addition of phosphatidylcholine and sodium taurocholate to the assays using the ethanol-dissolved substrate did not increase the activities observed. When the cholesteryl oleate was dispersed with phosphatidylcholine only (molar ratio, 1:4) the activity of the two neutral cholesteryl ester hydrolases was also decreased considerably compared to that found with mixed micelles. In this case, however, approx. 60% of the cytosolic, but only 10% of the microsomal activity, was restored by separate addition of sodium taurocholate. The activities of both the microsomal and the cytosolic neutral cholesteryl ester hydrolases were inhibited by MgCl2, and this inhibition was almost completely reversed by the addition of an equimolar concentration of ATP. At a fixed concentration of MgCl2 increasing concentrations of ATP increased the enzyme activities in a dose-dependent way. The activity of the microsomal, but not the cytosolic enzyme was enhanced by a cyclic AMP-dependent protein kinase and both activities were inhibited by alkaline phosphatase (bovine milk). These results provide evidence for the regulation of neutral cholesteryl ester hydrolases in the rat lactating mammary gland by mechanisms involving phosphorylation-dephosphorylation and therefore suggest that these enzymes may be under hormonal control.
Assuntos
Lactação/metabolismo , Glândulas Mamárias Animais/enzimologia , Esterol Esterase/metabolismo , Trifosfato de Adenosina/farmacologia , Fosfatase Alcalina/farmacologia , Animais , AMP Cíclico/farmacologia , Citosol/enzimologia , Ácido Edético/farmacologia , Feminino , Concentração de Íons de Hidrogênio , Cinética , Cloreto de Magnésio/farmacologia , Glândulas Mamárias Animais/ultraestrutura , Micelas , Microssomos/enzimologia , Fosfatidilcolinas/farmacologia , Fosforilação , Gravidez , Proteínas Quinases/metabolismo , Proteínas Quinases/farmacologia , Ratos , Ratos Endogâmicos , Fluoreto de Sódio/farmacologia , Ácido Taurocólico/farmacologiaRESUMO
INTRODUCTION: Ameloblastomas are the most frequent odontogenic tumors of the maxilla. In spite of their benign cytohistological appearance, they behave as invasive recurring tumors, with the possibility of metastasis. FNAB is a rapid, bloodless test that provides a pre-surgical diagnosis, thus, on occasions avoiding the need for diagnostic biopsies. We present the cytological characteristics of two cases of jugal recurrences of mandibular ameloblastomas diagnosed by FNAB, as well as their cytohistological correlation. CLINICAL CASES: Two patients, a 36-year-old woman, and a 62-year-old male who both attended with mandibular swelling of a few months evolution. In both cases the first diagnostic approximation was the histological study of the tumoral mass, together with the radiological studies. Following therapeutic extirpation both cases recurred. The diagnosis of the recurrences was established cytologically by means of FNAB. The cytologic smears revealed a granular background with isolated macrophages and giant multinucleate cells and an abundant epithelial cellularity of basaloid appearance arranged in cohesive groups forming images of peripheral palidasing, as well as small groups of squamous metaplastic cells. DISCUSSION: FNAB is considered to be a rapid, bloodless and reliable method for the diagnosis of ameloblastoma. The cytology of these tumors reveals components of the lesion that, in general, are sufficient for the diagnosis of ameloblastoma, especially in cases of recurrence.
Assuntos
Ameloblastoma/patologia , Neoplasias Mandibulares/patologia , Adulto , Biópsia por Agulha Fina , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/diagnósticoRESUMO
We report cloning and sequencing of gene ps1 encoding a versatile peroxidase combining catalytic properties of lignin peroxidase (LiP) and manganese peroxidase (MnP) isolated from lignocellulose cultures of the white-rot fungus Pleurotus eryngii. The gene contains 15 putative introns, and the deduced amino acid sequence consists of a 339-residue mature protein with a 31-residue signal peptide. Several putative response elements were identified in the promoter region. Amino acid residues involved in oxidation of Mn(2+) and aromatic substrates by direct electron transfer to heme and long-range electron transfer from superficial residues as predicted by analogy with Phanerochaete chrysosporium MnP and LiP, respectively. A dendrogram is presented illustrating sequence relationships between 29 fungal peroxidases.
Assuntos
Celulose/metabolismo , Clonagem Molecular , Lignina/metabolismo , Peroxidase/metabolismo , Pleurotus/enzimologia , Sequência de Aminoácidos , Sequência de Bases , Meios de Cultura , Fungos/enzimologia , Fungos/genética , Genes Fúngicos , Dados de Sequência Molecular , Peroxidase/química , Peroxidase/genética , Pleurotus/genética , Pleurotus/crescimento & desenvolvimento , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
Pyrrole was electropolymerized onto a Pt electrode in the presence of LiClO(4) and horseradish peroxidase (HRP). This HRP-based biosensor has been used for the amperometric detection of rifampicin (RIF) in the presence of a constant concentration of H(2)O(2). The C(H(2)O(2)) as well as the applied potential (E(ap)) and the pH of the phosphate buffer have simultaneously been optimized through a central composite design. Under these conditions, repeatability, reproducibility, and stability of the modified electrode have been analyzed. The detection limit for RIF has been calculated taking into account the probability of false-positive (alpha) and -negative (beta), reaching a value of 5.06x10(-6) mol dm(-3). The biosensor was applied to the determination of RIF in pharmaceutical preparations and biological samples.
Assuntos
Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Materiais Revestidos Biocompatíveis/química , Eletroquímica/instrumentação , Eletroquímica/métodos , Peroxidase do Rábano Silvestre/química , Rifampina/análise , Rifampina/química , Contaminação de Medicamentos/prevenção & controle , Enzimas Imobilizadas/química , Polímeros/química , Pirróis/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Urinálise/instrumentação , Urinálise/métodosRESUMO
Screening to detect genes encoding lignin peroxidase (LiP) and aryl-alcohol oxidase (AAO) has been carried out with 30 fungal strain using DNA probes from genes lpo of Phanerochaete chrysosporium (encoding LiP isoenzyme H8) and aao of Pleurotus eryngii. Evidence for the presence of genes closely related to lpo was found in Bjerkandera adusta, Fomes fomentarius, Ganoderma applanatum, Ganoderma australe, Lentinula degener, Peniophora gigantea, P. chrysosporium, Phanerochaete flavido-alba and Trametes tersicolor, whereas the gene aao was detected in Pleurotus species and B. adusta. The presence of both genes was only detected in B. adusta. These results suggest that different enzymatic system, formed by enzymes encoded by different genes, are responsible for lignin degradation by white-rot fungi.
Assuntos
Oxirredutases do Álcool/genética , Basidiomycota/enzimologia , Basidiomycota/genética , Peroxidases/genética , Oxirredutases do Álcool/metabolismo , Biodegradação Ambiental , Southern Blotting , DNA Fúngico/análise , Lignina/metabolismo , Peroxidases/metabolismoRESUMO
PURPOSE: To compare the in vitro adherence of slime-producing and non-slime-producing Staphylococcus epidermidis to different intraocular lenses (IOLs) to study the organism's contribution to postoperative endophthalmitis. METHODS: Strains of slime-positive (ATCC 35984) and slime-negative (ATCC 12228) S epidermidis were used. The IOLs were made of poly(methyl methacrylate) (PMMA), PMMA with polypropylene haptics, silicone, hydrogel, acrylic, heparin-surface-modified (HSM) PMMA, and fluorine-surface-modified PMMA. The lenses were incubated overnight with bacteria, then sonicated and vortexed to separate the adhered bacteria. Quantitative cultures were performed and the results statistically analyzed. RESULTS: Slime-negative strains of S epidermidis adhered to all IOLs but at a lower level than slime-positive strains. The most adherent lenses were acrylic with the positive strain and PMMA with the negative strain. The least adherent IOLs were PMMA with the positive strain and hydrogel with the negative strain. There were no significant differences between rigid and foldable lenses. Polypropylene was significantly more adherent than PMMA to the slime-positive strain. The acrylic and the HSM PMMA IOLs were significantly more adherent to the positive strain. CONCLUSIONS: In vitro, there were significant differences in bacterial adhesion among IOL materials. Slime-positive strains of S epidermidis were more adherent than slime-negative ones.
Assuntos
Aderência Bacteriana , Lentes Intraoculares/microbiologia , Staphylococcus epidermidis/fisiologia , Materiais Biocompatíveis , Contagem de Colônia Microbiana , Endoftalmite/microbiologia , Infecções Oculares Bacterianas/microbiologia , Humanos , Técnicas In Vitro , Polimetil Metacrilato , Elastômeros de Silicone , Infecções Estafilocócicas/microbiologia , Infecção da Ferida Cirúrgica/microbiologiaRESUMO
A method using differential pulse anodic stripping voltammetry after microwave oven digestion was developed for the simultaneous determination of Cd(II) and Pb(II) in the deciduous teeth of children. Each tooth was weighed; deposited in a 120 mL capped Teflon vessel with 5 mL 65% nitric acid, Suprapur analytical grade; and digested in a 2-step microwave oven for 15 min. The detection limits for Cd(II) and Pb(II) in the final solution were 0.078 and 0.323 microg/L, and the quantitation limits 0.394 and 1.613 microg/L, respectively, with a linearity range of 2 microg/L for Cd(II) and 23.3 microg/L for Pb(II). The sensitivity was 2.51 nA/microg-L and 1.37 nA/microg-L, for Cd(II) and Pb(II). The main advantages of this technique are a complete and satisfactory dissolution of the tooth material with the proposed microwave oven digestion procedure, without sample pretreatments, such as drying, ashing, or powdering. The voltammetric procedure proved to be well designed because of significant goodness of fit to a linear model, and the accuracy of the method was established as compared with standard reference material. The methodology has enabled us to study Cd(II) and Pb(II) in 371 deciduous teeth from school children in Cartagena, Spain.
Assuntos
Cádmio/análise , Chumbo/análise , Dente/química , Adolescente , Poluentes Atmosféricos/análise , Calibragem , Criança , Pré-Escolar , Eletroquímica , Feminino , Humanos , Indicadores e Reagentes , Masculino , Micro-Ondas , Soluções , Espanha , Tempo (Meteorologia)RESUMO
The purpose of the study was to determine the accumulation of lead in deciduous teeth in children living in the area of Pamplona (Spain). In this manner, we tried to make a relationship between the quantity of lead accumulated in the tooth against certain factors of exposure that were documented on a questionnaire carried out at the time that the tooth was presented. We analysed 457 deciduous teeth using a technique of microwave digestion follow by Atomic Absorption Spectrometry (AAS), to determine the concentration of lead in the sample. The mean lead concentration was 2.60+/-1.36 microg/g (range 0.25-10.71 microg/g). The lead concentration in our study is inferior to those observed in other European studies.
RESUMO
The heterogeneity of biomass makes it difficult if not impossible to make sweeping generalizations concerning thermochemical treatment systems and the optimal equipment to be used in them. Chemical differences in the structural components of the biomass (cellulose, hemicellulose, and lignin) have a direct impact on its chemical reactivity. The aim of this research was to study the influence of the organic components of the raw material from olive trees (leaves, pruning residues, and wood) in the combustion behavior of this biomass, as well as to find the component responsible for the higher ash content of olive leaves. Accordingly, the study used a thermogravimetric analyzer to monitor the different states and complex transitions that occurred in the biomass as the temperature varied. The decomposition rates of the different samples were analyzed in order to establish a link between each combustion phase and the composition of the raw materials. Two methods were used to determine the hemicellulose and cellulose contents of biomass from olive trees. Significant differences among the results obtained by the different methods were observed, as well as important variations regarding the chemical composition and consequently the thermal behavior of the raw materials tested.
Assuntos
Biocombustíveis/análise , Biomassa , Olea/química , Lignina/análise , Folhas de Planta/química , Polissacarídeos/análise , Termogravimetria , Madeira/químicaRESUMO
Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder characterised by sparse hair, lack of sweat glands and malformation of teeth. The X-linked form of the disease, caused by mutations in the EDA gene, represents the majority of HED cases. Autosomal forms result from mutations in either the EDAR or the EDARADD gene. The X-linked and autosomal forms are phenotypically indistinguishable. For the purpose of genetic counselling, it is, therefore, important to know which gene is involved. In this study, we ascertained a Spanish family demonstrating the autosomal recessive form of HED. Affected individuals in the family showed the characteristic features of HED, including fine and sparse scalp hair, sparse eyebrows and eyelashes, periorbital hyperpigmentation, prominent lips, hypodontia and conical teeth, reduced sweating, and dry and thin skin. Sequence analysis of the EDAR gene revealed a novel compound heterozygous mutation [c.52-2A>G; c.212G>A (p.Cys71Tyr)]. Our finding extends the body of evidence that supports the significance of the EDAR signalling pathway in the ectodermal morphogenesis.
Assuntos
Análise Mutacional de DNA , Displasia Ectodérmica Hipo-Hidrótica Autossômica Recessiva/genética , Receptor Edar/genética , Adulto , Anodontia , Displasia Ectodérmica Hipo-Hidrótica Autossômica Recessiva/diagnóstico , Displasia Ectodérmica Hipo-Hidrótica Autossômica Recessiva/fisiopatologia , Ectodisplasinas/genética , Ectodisplasinas/metabolismo , Receptor Edar/metabolismo , Proteína de Domínio de Morte Associada a Edar/genética , Proteína de Domínio de Morte Associada a Edar/metabolismo , Família , Feminino , Heterozigoto , Humanos , Hiperpigmentação , Masculino , Mutação/genética , Linhagem , EspanhaRESUMO
Aryl-alcohol oxidase (AAO), an extracellular enzyme characteristic of fungi from the genus Pleurotus, constitutes a source for H2O2 required in lignin biodegradation. The gene aao has been cloned, sequenced and characterized for the first time in Pleurotus eryngii. Both cDNA and genomic libraries were screened with probes obtained by PCR using as primers oligonucleotides corresponding to the N-terminus and internal sequences of AAO. DNA sequences from positive clones showed a unique open reading frame of 1779 nucleotides interrupted by 12 introns. The conceptual translation of the protein agrees with the partial amino acid sequences obtained from protein sequencing. A search for proteins with related amino-acid sequences revealed that glucose oxidase from Aspergillus niger has 33% identity and 51% similarity. A comparison with other oxidoreductases showed common motifs in both N- and C-terminal regions corresponding, respectively, to the FAD-binding region and the enzyme active site. However, AAO probably has structural differences with other oxidases, as deduced from its unique ability to generate H2O2 from the oxidation of aromatic alcohols.
Assuntos
Oxirredutases do Álcool/genética , Genes Fúngicos , Lignina/metabolismo , Pleurotus/genética , Oxirredutases do Álcool/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Sítios de Ligação/genética , Domínio Catalítico/genética , Clonagem Molecular , Flavina-Adenina Dinucleotídeo , Dados de Sequência Molecular , Pleurotus/enzimologia , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
We report here on bioturbation traces, with micro-dendrite textures, composed of a mixture of altered aluminum and polycarbonate, which have been developed in a common compact disk (CD), destroying information pits. Fungal hyphae proliferated in these deteriorated zones, and Geotrichum-type fungus was isolated from surface-sterilized CD fragments. The severe biodeterioration described is attributed to the slow growth of this arthroconidial fungus on the CD material in the tropical indoor environment of Belize, Central America (approximately 30 degrees C, approximately 90% humidity).
Assuntos
Discos Compactos , Geotrichum/crescimento & desenvolvimento , Alumínio , Belize , Geotrichum/classificação , Geotrichum/isolamento & purificação , Cimento de Policarboxilato , Clima TropicalRESUMO
A variety of simple aromatic compounds were identified in liquid cultures of the basidiomycetes Pleurotus cornucopiae, P. eryngii, P. floridanus, P. pulmonarius, P. ostreatus, and P. sajor-caju by using gas chromatography-mass spectrometry. Such compounds were detected in fungal cultures on lignin- and straw-containing media, but it was found that they were also produced in the absence of aromatic precursors. Anisylic and hydroxybenzylic compounds (such as alcohols, aldehydes, and acids) were identified, p-anisaldehyde being the most characteristic extracellular metabolite synthesized by these ligninolytic fungi. Small amounts of 3-chloro-p-anisaldehyde were also detected in several species. It is postulated that the balance between the more-or-less-oxidized aromatic compounds can be explained in terms of the activity of fungal enzymes, including aryl-alcohol oxidase and dehydrogenase. The former enzyme shows high affinity for p-anisyl alcohol, which is oxidized to p-anisaldehyde with production of H2O2. The aryl-alcohol dehydrogenase was detected only in the mycelium, where it reduces aromatic aldehydes in the presence of NADPH. Both enzymes could be involved in the redox cycling of these aromatic compounds, providing H2O2 to ligninolytic peroxidases.
Assuntos
Oxirredutases do Álcool/metabolismo , Benzaldeídos/metabolismo , Polyporaceae/metabolismo , Biodegradação Ambiental , Lignina/metabolismo , Polyporaceae/enzimologia , Especificidade da EspécieRESUMO
Quinone redox cycling is generally known as an intracellular process that implies the reduction of quinones (Q) into semiquinones (Q-.) or hydroquinones (QH2), which autoxidize reducing oxygen to superoxide anion radical (O-.2). We demonstrate here for the first time the existence of quinone redox cycling in a ligninolytic fungus, Pleurotus eryngii, showing two particularities: extracellular production of O-.2 and involvement of ligninolytic enzymes. Experiments were performed with P. eryngii cultures, showing laccase activity, and four quinones: 1,4-benzoquinone (BQ), 2-methyl-1,4-benzoquinone (MeBQ), 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ), and 2-methyl-1,4-naphthoquinone (menadione, MD). The overall process consisted of cell-bound divalent reduction of quinones, followed by extracellular laccase-mediated oxidation of hydroquinones into semiquinones, which autoxidized to a certain extent producing O-.2 (at the pH values of natural degradation of lignin, some autoxidation of hydroquinones was observed only with DQH2 and MDH2). The existence of a redox cyclic system involving quinones was evidenced by determining the chemical state of quinones along incubation under several conditions (either different O2 concentrations and pH values or laccase amounts). Thus, QH2/Q ratios at system equilibrium decreased as either pH values and oxygen concentration (allowing hydroquinones autoxidation) or the amount of laccase increased. Once the cyclic nature of the system was demonstrated, special attention was paid to the production of O-.2 during hydroquinone oxidation. Except in the case of BQH2, production of O-.2 was found in samples containing hydroquinones and laccase. By the use of agents promoting the autoxidation of semiquinones (superoxide dismutase and Mn2+), production of O-.2 during oxidation of BQH2 could finally be demonstrated.
Assuntos
Lignina/metabolismo , Polyporaceae/metabolismo , Quinonas/metabolismo , Superóxidos/metabolismo , Concentração de Íons de Hidrogênio , Oxirredução , Espécies Reativas de Oxigênio/metabolismo , Espectrofotometria UltravioletaRESUMO
We investigated the transformation of six industrial azo and phthalocyanine dyes by ligninolytic peroxidases from Bjerkandera adusta and other white rot fungi. The dyes were not oxidized or were oxidized very little by Phanerochaete chrysosporium manganese peroxidase (MnP) or by a chemically generated Mn3+-lactate complex. Lignin peroxidase (LiP) from B. adusta also showed low activity with most of the dyes, but the specific activities increased 8- to 100-fold when veratryl alcohol was included in the reaction mixture, reaching levels of 3.9 to 9.6 U/mg. The B. adusta and Pleurotus eryngii MnP isoenzymes are unusual because of their ability to oxidize aromatic compounds like 2,6-dimethoxyphenol and veratryl alcohol in the absence of Mn2+. These MnP isoenzymes also decolorized the azo dyes and the phthalocyanine complexes in an Mn2+-independent manner. The reactions with the dyes were characterized by apparent Km values ranging from 4 to 16 microM and specific activities ranging from 3.2 to 10.9 U/mg. Dye oxidation by these peroxidases was not increased by adding veratryl alcohol as it was in LiP reactions. Moreover, the reaction was inhibited by the presence of Mn2+, which in the case of Reactive Black 5, an azo dye which is not oxidized by the Mn3+-lactate complex, was found to act as a noncompetitive inhibitor of dye oxidation by B. adusta MnP1.