RESUMO
RNA is a fundamental nucleic acid for life and it plays important roles in the regulation of gene transcription, post-transcriptional regulation, and epigenetic regulation. Recently, the focus on this nucleic acid has significantly increased due to the development of mRNA vaccines and RNA-based gene therapy protocols. Unfortunately, RNA based products show constrains mainly owing to instability and easy degradability of the RNA molecules. Indeed, unlike the DNA molecule which has a great intrinsic stability, RNA is more prone to degradation and this process is accelerated under thermal treatment. Here we describe a method that involves the use of Natural Deep Eutectic Solvents (NaDES) capable of slowing down RNA degradation process. Our results show that this technology seems suitable for improving the stability of specific RNA molecules particularly susceptible to thermal-induced degradation. Therefore, this technique represents a valuable tool to stabilize RNA molecules used in gene therapy and mRNA vaccines.
Assuntos
Solventes Eutéticos Profundos , RNA , Solventes , Epigênese Genética , Extratos VegetaisRESUMO
trans-Resveratrol is a natural bioactive compound with well-recognized health promoting effects. When exposed to UV light, this compound can undergo a photochemically induced trans/cis isomerization and a 6π electrochemical cyclization with the subsequent formation of 2,4,6-trihydroxyphenanthrene (THP). THP is a potentially harmful compound which can exert genotoxic effects. In this work we improved the chromatographic separation and determination of the two resveratrol isomers and of THP by using a non-commercial pentafluorophenyl stationary phase. We assessed the effect of natural deep eutectic solvents (NaDES) as possible photo-protective agents by evaluating cis-resveratrol isomer and THP formation under different UV-light exposure conditions with the aim of enhancing resveratrol photostability and inhibiting THP production. Our results demonstrate a marked photoprotective effect exerted by glycerol-containing NaDES, and in particular by proline/glycerol NaDES, which exerts a strong inhibitory effect on the photochemical isomerization of resveratrol and significantly limits the formation of the toxic derivative THP. Considering the presence of resveratrol in various commercial products, these results are of note in view of the potential genotoxic risk associated with its photochemical degradation products and in view of the need for the development of green, eco-sustainable and biocompatible resveratrol photo-stable formulations.
Assuntos
Solventes Eutéticos Profundos , Glicerol , Isomerismo , Fenantrenos , Resveratrol/química , Resveratrol/farmacologia , Solventes/químicaRESUMO
Extra virgin olive oil (EVOO) phenols represent a significant part of the intake of antioxidants and bioactive compounds in the Mediterranean diet. In particular, hydroxytyrosol (HTyr), tyrosol (Tyr), and the secoiridoids oleacein and oleocanthal play central roles as anti-inflammatory, neuro-protective and anti-cancer agents. These compounds cannot be easily obtained via chemical synthesis, and their isolation and purification from EVOO is cumbersome. Indeed, both processes involve the use of large volumes of organic solvents, hazardous reagents and several chromatographic steps. In this work we propose a novel optimized procedure for the green extraction, isolation and purification of HTyr, Tyr, oleacein and oleocanthal directly from EVOO, by using a Natural Deep Eutectic Solvent (NaDES) as an extracting phase, coupled with preparative high-performance liquid chromatography. This purification method allows the total recovery of the four components as single pure compounds directly from EVOO, in a rapid, economic and ecologically sustainable way, which utilizes biocompatible reagents and strongly limits the use or generation of hazardous substances.
Assuntos
Aldeídos/isolamento & purificação , Fracionamento Químico/métodos , Cromatografia Líquida de Alta Pressão/métodos , Monoterpenos Ciclopentânicos/isolamento & purificação , Azeite de Oliva/química , Fenóis/isolamento & purificação , Álcool Feniletílico/análogos & derivados , Extratos Vegetais/isolamento & purificação , Álcool Feniletílico/isolamento & purificaçãoRESUMO
Spermine oxidase (SMOX) is a flavin-containing enzyme that specifically oxidizes spermine to produce spermidine, 3-aminopropanaldehyde and hydrogen peroxide. While no crystal structure is available for any mammalian SMOX, X-ray crystallography showed that the yeast Fms1 polyamine oxidase has a dimeric structure. Based on this scenario, we have investigated the quaternary structure of the SMOX protein by native gel electrophoresis, which revealed a composite gel band pattern, suggesting the formation of protein complexes. All high-order protein complexes are sensitive to reducing conditions, showing that disulfide bonds were responsible for protein complexes formation. The major gel band other than the SMOX monomer is the covalent SMOX homodimer, which was disassembled by increasing the reducing conditions, while being resistant to other denaturing conditions. Homodimeric and monomeric SMOXs are catalytically active, as revealed after gel staining for enzymatic activity. An engineered SMOX mutant deprived of all but two cysteine residues was prepared and characterized experimentally, resulting in a monomeric species. High-sensitivity differential scanning calorimetry of SMOX was compared with that of bovine serum amine oxidase, to analyse their thermal stability. Furthermore, enzymatic activity assays and fluorescence spectroscopy were used to gain insight into the unfolding process.
Assuntos
Amina Oxidase (contendo Cobre)/química , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/química , Desnaturação Proteica , Multimerização Proteica , Amina Oxidase (contendo Cobre)/genética , Animais , Bovinos , Estabilidade Enzimática , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Poliamina OxidaseRESUMO
The present work describes the development and optimization of electrochemical biosensors for specific determination of the biogenic polyamine spermine (Spm) and spermidine (Spmd) whose assessment represents a novel important analytical tool in food analysis and human diagnostics. These biosensors have been prepared using novel engineered enzymes: polyamine oxidase (PAO) endowed with selectivity towards Spm and Spmd and spermine oxidase (SMO) characterized by strict specificity towards Spm. The current design entails biosensors in which the enzymes were entrapped in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ), a photocrosslinkable gel, onto an electrode surface. Screen-printed electrodes (SPEs) were used as electrochemical transducers for enzymatically produced hydrogen peroxide, operating at different potential vs Ag/AgCl according to the material of the working electrode (WE): +700 mV for graphite (GP) or -100 mV for Prussian blue (PB)-modified SPE, respectively. Biosensor performances were evaluated by means of flow injection amperometric (FIA) measurements. The modified electrodes showed good sensitivity, long-term stability and reproducibility. Under optimal conditions, the PAO biosensor showed a linear range 0.003-0.3 mM for Spm and 0.01-0.4 mM for Spmd, while with the SMO biosensor, a linear range of 0.004-0.5 mM for Spm has been obtained. The main kinetic parameters apparent Michaelis constant (K M), turnover number (K cat) and steady-state current (I max) were determined. The proposed device was then applied to the determination of biogenic amines in blood samples. The results obtained were in good agreement with those obtained with the GC-MS reference method.
Assuntos
Amina Oxidase (contendo Cobre)/metabolismo , Técnicas Biossensoriais/métodos , Enzimas Imobilizadas/metabolismo , Espermina/análise , Técnicas Biossensoriais/instrumentação , Humanos , Limite de Detecção , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Proteínas Recombinantes , Espermidina/análise , Espermidina/sangue , Espermina/sangue , Especificidade por Substrato , Zea mays/enzimologia , Poliamina OxidaseRESUMO
SMO (spermine oxidase) and APAO (acetylpolyamine oxidase) are flavoenzymes that play a critical role in the catabolism of polyamines. Polyamines are basic regulators of cell growth and proliferation and their homoeostasis is crucial for cell life since dysregulation of polyamine metabolism has been linked with cancer. In vertebrates SMO specifically catalyses the oxidation of spermine, whereas APAO displays a wider specificity, being able to oxidize both N¹-acetylspermine and N¹-acetylspermidine, but not spermine. The molecular bases of the different substrate specificity of these two enzymes have remained so far elusive. However, previous molecular modelling, site-directed mutagenesis and biochemical characterization studies of the SMO enzyme-substrate complex have identified Glu²¹6-Ser²¹8 as a putative active site hot spot responsible for SMO substrate specificity. On the basis of these analyses, the SMO double mutants E216L/S218A and E216T/S218A have been produced and characterized by CD spectroscopy and steady-state and rapid kinetics experiments. The results obtained demonstrate that mutation E216L/S218A endows SMO with N¹-acetylspermine oxidase activity, uncovering one of the structural determinants that confer the exquisite and exclusive substrate specificity of SMO for spermine. These results provide the theoretical bases for the design of specific inhibitors either for SMO or APAO.
Assuntos
Modelos Moleculares , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Substituição de Aminoácidos , Animais , Domínio Catalítico , Dicroísmo Circular , Ácido Glutâmico/química , Cinética , Camundongos , Mutagênese Sítio-Dirigida , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Oxirredução , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/química , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Conformação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Serina/química , Espermina/análogos & derivados , Espermina/química , Espermina/metabolismo , Especificidade por Substrato , Zea mays/enzimologia , Poliamina OxidaseRESUMO
Polyamine oxidases (PAOs) are flavin-dependent enzymes involved in polyamine catabolism. In Arabidopsis five PAO genes (AtPAO1-AtPAO5) have been identified which present some common characteristics, but also important differences in primary structure, substrate specificity, subcellular localization, and tissue-specific expression pattern, differences which may suggest distinct physiological roles. In the present work, AtPAO5, the only so far uncharacterized AtPAO which is specifically expressed in the vascular system, was partially purified from 35S::AtPAO5-6His Arabidopsis transgenic plants and biochemically characterized. Data presented here allow AtPAO5 to be classified as a spermine dehydrogenase. It is also shown that AtPAO5 oxidizes the polyamines spermine, thermospermine, and N(1)-acetylspermine, the latter being the best in vitro substrate of the recombinant enzyme. AtPAO5 also oxidizes these polyamines in vivo, as was evidenced by analysis of polyamine levels in the 35S::AtPAO5-6His Arabidopsis transgenic plants, as well as in a loss-of-function atpao5 mutant. Furthermore, subcellular localization studies indicate that AtPAO5 is a cytosolic protein undergoing proteasomal control. Positive regulation of AtPAO5 expression by polyamines at the transcriptional and post-transcriptional level is also shown. These data provide new insights into the catalytic properties of the PAO gene family and the complex regulatory network controlling polyamine metabolism.
Assuntos
Arabidopsis/enzimologia , Regulação da Expressão Gênica de Plantas , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Poliaminas/metabolismo , Sequência de Aminoácidos , Arabidopsis/citologia , Arabidopsis/genética , Regulação Enzimológica da Expressão Gênica , Genes Reporter , Cinética , Dados de Sequência Molecular , Mutação , Especificidade de Órgãos , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Raízes de Plantas/citologia , Raízes de Plantas/enzimologia , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , Complexo de Endopeptidases do Proteassoma , Proteínas Recombinantes de Fusão , Plântula/citologia , Plântula/enzimologia , Plântula/genética , Alinhamento de Sequência , Regulação para Cima , Poliamina OxidaseRESUMO
This review provides an update on histamine, on diamine oxidase (DAO) and on their implications in allergy and various conditions or affections, such as food histaminosis, ischemia and inflammatory bowel diseases (IBD). The review also presents, in brief, patent coverage on therapies for allergy and IBD with the focus on histamine-related treatments.
Assuntos
Amina Oxidase (contendo Cobre)/uso terapêutico , Histamina/metabolismo , Hipersensibilidade/terapia , Doenças Inflamatórias Intestinais/terapia , Mastócitos/imunologia , Proteínas de Plantas/uso terapêutico , Amina Oxidase (contendo Cobre)/metabolismo , Animais , Benzilamina Oxidase/sangue , Bovinos , Histamina/imunologia , Humanos , Mastócitos/efeitos dos fármacos , Patentes como Assunto , Proteínas de Plantas/metabolismo , Traumatismo por Reperfusão/terapiaRESUMO
Acetylpolyamine and spermine oxidases are involved in the catabolism of polyamines. The discovery of selective inhibitors of these enzymes represents an important tool for the development of novel anti-neoplastic drugs. Here, a comparative study on acetylpolyamine and spermine oxidases inhibition by the polyamine analogue chlorhexidine is reported. Chlorhexidine is an antiseptic diamide, commonly used as a bactericidal and bacteriostatic agent. Docking simulations indicate that chlorhexidine binding to these enzymes is compatible with the stereochemical properties of both acetylpolyamine oxidase and spermine oxidase active sites. In fact, chlorhexidine is predicted to establish several polar and hydrophobic interactions with the active site residues of both enzymes, with binding energy values ranging from -7.6 to -10.6 kcal/mol. In agreement with this hypothesis, inhibition studies indicate that chlorhexidine behaves as a strong competitive inhibitor of both enzymes, values of Ki being 0.10 µM and 0.55 µM for acetylpolyamine oxidase and spermine oxidase, respectively.
Assuntos
Clorexidina/farmacologia , Inibidores Enzimáticos/farmacologia , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/antagonistas & inibidores , Animais , Domínio Catalítico , Camundongos , Modelos Moleculares , Simulação de Acoplamento Molecular/métodos , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/química , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Conformação Proteica , Putrescina/análogos & derivados , Putrescina/farmacologia , Poliamina OxidaseRESUMO
This chapter describes a zymographic assay of oxidases which is based on a coupled peroxidase or hemin reaction. The enzymatic activity of oxidases (i.e., diamine oxidase/DAO, glucose oxidase, galactose oxidase) can be directly monitored on polyacrylamide gels containing horseradish peroxidase or hemin, in the presence of their specific substrates and ortho-phenylenediamine (OPDA), an oxidizable chromogen. In the presence of hydrogen peroxide, OPDA is oxidized to azo-aniline, which led to well-defined yellow-brown bands on gels, with intensities corresponding to the enzymatic activity of oxidases.
Assuntos
Ensaios Enzimáticos/métodos , Enzimas Imobilizadas/química , Hemina/química , Oxirredutases/química , Resinas Acrílicas/química , Compostos Cromogênicos/química , Corantes/química , Eletroforese em Gel de Poliacrilamida/métodos , Enzimas Imobilizadas/isolamento & purificação , Proteínas Fúngicas/química , Proteínas Fúngicas/isolamento & purificação , Peróxido de Hidrogênio/química , Limite de Detecção , Oxirredução , Oxirredutases/isolamento & purificação , Fenilenodiaminas/química , Proteínas de Plantas/química , Proteínas de Plantas/isolamento & purificação , Conformação Proteica , Putrescina/química , Corantes de Rosanilina/química , Coloração e RotulagemRESUMO
AIM: The aim of this study was to evaluate the utility of a simple colorimetric chair side test detecting amines in saliva as an adjunct test in the oral malodour diagnosis. MATERIAL AND METHODS: Non-stimulated saliva samples were collected from 100 volunteers with different degrees of oral malodour. The amount of amines detected by the test was estimated clinically (colorimetric test), confirmed semi quantitatively in the laboratory (standard addition method) and consequently compared with (i) the organoleptic score (OLS); (ii) the volatile sulphur compounds (VSCs) levels (OralChroma(™)) and (iii) the amount of amines detected by means of gas chromatography - mass spectroscopy. RESULTS: The chair side test correlated well (Spearman correlation coefficient: 0.46-0.77), with the OLS, the level of VSCs, and the amines determined by using gas chromatography - mass spectroscopy. The results of the new test for patients with and without oral malodour were significantly different (Mann-Whitney U-test, p < 0.0001). The sensitivity, specificity, and positive and negative predictive value of this chair side test were similar to those of the VSCs evaluations. CONCLUSIONS: These results support the "fit for purpose" of the new chair side test as adjunctive diagnostic tool for oral malodour.
Assuntos
Colorimetria/métodos , Halitose/diagnóstico , Adolescente , Adulto , Idoso , Aminas/análise , Placa Dentária/classificação , Dissulfetos/análise , Feminino , Cromatografia Gasosa-Espectrometria de Massas/métodos , Gengivite/classificação , Halitose/metabolismo , Hemiterpenos , Humanos , Sulfeto de Hidrogênio/análise , Masculino , Pessoa de Meia-Idade , Índice de Higiene Oral , Ácidos Pentanoicos/análise , Bolsa Periodontal/classificação , Sistemas Automatizados de Assistência Junto ao Leito , Putrescina/análise , Saliva/química , Sensibilidade e Especificidade , Escatol/análise , Compostos de Sulfidrila/análise , Sulfetos/análise , Compostos de Enxofre/análise , Língua/patologia , Compostos Orgânicos Voláteis/análise , Adulto JovemRESUMO
The capacity of carboxymethyl starch (CMS):Chitosan monolithic tablets to protect diamine oxidase and/or catalase therapeutic enzymes against simulated gastric fluid (SGF) and to control their delivery in simulated intestinal fluid (SIF) was investigated. Enzyme formulations loaded with grass pea seedlings diamine oxidase (PSDAO) vegetal extract, catalase, or PSDAO associated to catalase, were obtained by direct compression. The CMS:Chitosan (1:1) matrix afforded a good gastric protection to PSDAO and to catalase, when each enzyme was formulated separately. Variable amounts of DAO were delivered in the SIF containing pancreatin, with maximal release reached at about 8h, a time convenient for tablets to attain the colon. Up to 50% of the initial enzymatic activity of catalase formulated with CMS:Chitosan was found after 8 h in SIF. For the CMS:Chitosan tablets of bi-enzymatic formulations containing PSDAO:Catalase, the releases of DAO and of catalase were synchronized. The hydrogen peroxide (product of DAO activity) was decomposed by the catalase liberated in the same SIF environment. The proposed formulations could allow novel therapeutic approaches for the treatment of inflammatory bowel diseases, intestinal cancers or pseudo-allergic reactions.
Assuntos
Amina Oxidase (contendo Cobre)/química , Catalase/química , Quitosana/química , Intestinos/química , Amido/análogos & derivados , Sequência de Carboidratos , Química Farmacêutica/métodos , Preparações de Ação Retardada , Estabilidade de Medicamentos , Excipientes/química , Suco Gástrico/química , Peróxido de Hidrogênio/química , Mucosa Intestinal/metabolismo , Dados de Sequência Molecular , Amido/química , Comprimidos/químicaRESUMO
Polyamine oxidases (PAOs) are FAD-dependent enzymes involved in polyamine catabolism. In Arabidopsis thaliana, five PAOs (AtPAO1-5) are present with cytosolic or peroxisomal localization. Here, we present a detailed study of the expression pattern of AtPAO1, AtPAO2, AtPAO3 and AtPAO5 during seedling and flower growth and development through analysis of promoter activity in AtPAO::ß-glucuronidase (GUS) transgenic Arabidopsis plants. The results reveal distinct expression patterns for each studied member of the AtPAO gene family. AtPAO1 is mostly expressed in the transition region between the meristematic and the elongation zone of roots and anther tapetum, AtPAO2 in the quiescent center, columella initials and pollen, AtPAO3 in columella, guard cells and pollen, and AtPAO5 in the vascular system of roots and hypocotyls. Furthermore, treatment with the plant hormone abscisic acid induced expression of AtPAO1 in root tip and AtPAO2 in guard cells. These data suggest distinct physiological role(s) for each member of the AtPAO gene family.
Assuntos
Arabidopsis/enzimologia , Flores , Regulação da Expressão Gênica de Plantas , Família Multigênica , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Sequência de Bases , Primers do DNA , Glucuronidase/genética , Plantas Geneticamente Modificadas , Poliamina OxidaseRESUMO
Metabolism of polyamines spermidine and spermine, and their diamine precursor, putrescine, has been a target for antineoplastic therapy since these naturally occurring alkyl amines were found essential for normal mammalian cell growth. Intracellular polyamine concentrations are maintained at a cell type-specific set point through the coordinated and highly regulated interplay between biosynthesis, transport, and catabolism. A correlation between regulation of cell proliferation and polyamine metabolism is described. In particular, polyamine catabolism involves copper-containing amine oxidases and FAD-dependent polyamine oxidases. Several studies showed an important role of these enzymes in several developmental and disease-related processes in both animals and plants through a control on polyamine homeostasis in response to normal cellular signals, drug treatment, environmental and/or cellular stressors. The production of toxic aldehydes and reactive oxygen species, H(2)O(2) in particular, by these oxidases using extracellular and intracellular polyamines as substrates, suggests a mechanism by which the oxidases can be exploited as antineoplastic drug targets. This minireview summarizes recent advances on the physiological roles of polyamine catabolism in animals and plants in an attempt to highlight differences and similarities that may contribute to determine in detail the underlined mechanisms involved. This information could be useful in evaluating the possibility of this metabolic pathway as a target for new antiproliferative therapies in animals and stress tolerance strategies in plants.
Assuntos
Adaptação Fisiológica , Poliaminas Biogênicas/metabolismo , Proliferação de Células , Fenômenos Fisiológicos Vegetais , Estresse Fisiológico , AnimaisRESUMO
Until now, the application of biogenic amines as bio-markers of oral malodour has been limited because of the complexity of their detection. This study explores the usability of a simple colorimetric reaction detecting amines in saliva as an adjunct test for the diagnosis of oral malodour. The colour reaction caused by a newly discovered enzyme capable of detecting amines in saliva was characterized in vitro. Two colour scales were developed by transforming the colours of selected dilutions of a mixture of cadaverine and putrescine into a 5- and a 10-point pink-colour scale. Afterwards, this new enzymatic test was used to assess the amount of amines in saliva samples of 50 volunteers with different degrees of oral malodour. The enzymatic reaction was shown to be linear towards the concentration of amines and stable over a time of ≥4 h. Colour scores correlated well with organoleptic scores and the volatile sulfur compounds. More importantly differences between patients with and without oral malodour were significant. Based on these results, we conclude that this new enzymatic test, interpreted by means of a simple colour scale, has the potential to be used as an adjunct chair-side test for oral malodour diagnosis.
Assuntos
Testes Respiratórios/métodos , Colorimetria/métodos , Halitose/diagnóstico , Saliva/química , Compostos de Enxofre/análise , Adolescente , Adulto , Idoso , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Boca , Reprodutibilidade dos Testes , Adulto JovemRESUMO
Spermidine (Spd) treatment inhibited root cell elongation, promoted deposition of phenolics in cell walls of rhizodermis, xylem elements, and vascular parenchyma, and resulted in a higher number of cells resting in G(1) and G(2) phases in the maize (Zea mays) primary root apex. Furthermore, Spd treatment induced nuclear condensation and DNA fragmentation as well as precocious differentiation and cell death in both early metaxylem and late metaxylem precursors. Treatment with either N-prenylagmatine, a selective inhibitor of polyamine oxidase (PAO) enzyme activity, or N,N(1)-dimethylthiourea, a hydrogen peroxide (H(2)O(2)) scavenger, reverted Spd-induced autofluorescence intensification, DNA fragmentation, inhibition of root cell elongation, as well as reduction of percentage of nuclei in S phase. Transmission electron microscopy showed that N-prenylagmatine inhibited the differentiation of the secondary wall of early and late metaxylem elements, and xylem parenchymal cells. Moreover, although root growth and xylem differentiation in antisense PAO tobacco (Nicotiana tabacum) plants were unaltered, overexpression of maize PAO (S-ZmPAO) as well as down-regulation of the gene encoding S-adenosyl-l-methionine decarboxylase via RNAi in tobacco plants promoted vascular cell differentiation and induced programmed cell death in root cap cells. Furthermore, following Spd treatment in maize and ZmPAO overexpression in tobacco, the in vivo H(2)O(2) production was enhanced in xylem tissues. Overall, our results suggest that, after Spd supply or PAO overexpression, H(2)O(2) derived from polyamine catabolism behaves as a signal for secondary wall deposition and for induction of developmental programmed cell death.
Assuntos
Poliaminas Biogênicas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Xilema/crescimento & desenvolvimento , Fragmentação do DNA , Fluorescência , Peróxido de Hidrogênio/metabolismo , Microscopia Eletrônica de Transmissão , Plantas Geneticamente Modificadas , Nicotiana/crescimento & desenvolvimento , Zea mays/crescimento & desenvolvimentoRESUMO
In this work, we have characterized a diamine oxidase (DAO) from Lathyrus sativus and evaluated its use, for the first time, as biocatalytic component of an electrochemical biosensor for the determination of biogenic amines index in wine and beer samples. Firstly, DAO was electrokinetically characterized free in solution by means of a platinum electrode and then immobilized by using polyazetidine prepolimer on the surface of screen-printed electrodes constituted of two gold working electrodes. The amperometric measurements were carried out by using a flow system at a fixed potential of +600 mV vs the internal silver pseudo reference in phosphate buffer solution (0.1 mol l(-1), pH = 7.4). The analysis of wine and beer samples were performed in flow injection system using the dual channel transducer providing simultaneous detection of sample and blank signal, and the resulting signal (after subtraction of the blank signal) was referred to that of putrescine. The results were compared with those obtained using a modified reference method based on gas chromatography-mass spectrometry analysis on the same samples. The results obtained in the analysis of Italian wines shows the better suitability of DAO-based biosensor in the determination of the biogenic amines (BAs) index expressed as putrescine equivalent in both red and white wines, being less efficient in beer samples where it underestimates by about 50% the BAs content.
Assuntos
Amina Oxidase (contendo Cobre)/química , Cerveja/análise , Aminas Biogênicas/análise , Técnicas Biossensoriais , Lathyrus/enzimologia , Vinho/análise , Amina Oxidase (contendo Cobre)/metabolismo , Biocatálise , Aminas Biogênicas/metabolismo , Eletroquímica , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Ouro/química , Platina/química , Propriedades de SuperfícieRESUMO
Polyamine oxidases are FAD-dependent enzymes catalyzing the oxidation of polyamines at the secondary amino groups. Zea mays PAO (ZmPAO) oxidizes the carbon on the endo-side of the N5-nitrogen of spermidine (Spd) and spermine (Spm). The structure of ZmPAO revealed that the active site is formed by a catalytic tunnel in which the N5 atom of FAD lies in close proximity to the K300 side chain, the only active-site residue conserved in all PAOs. A water molecule, (HOH309), is hydrogen-bound to the amino group of K300 and mutation of this residue results in a 1400-fold decrease in the rate of flavin reduction. The structural studies on the catalytically impaired ZmPAO-K300M mutant described here show that substrates are bound in an 'out-of-register' mode and the HOH309 water molecule is absent in the enzyme-substrate complexes. Moreover, K300 mutation brings about a 60 mV decrease in the FAD redox potential and a 30-fold decrease in the FAD reoxidation rate, within a virtually unaltered geometry of the catalytic pocket. Taken together, these results indicate that the HOH309-K300 couple plays a major role in multiple steps of ZmPAO catalytic mechanism, such as correct substrate binding geometry as well as FAD reduction and reoxidation kinetics.
Assuntos
Oxirredutases atuantes sobre Doadores de Grupo CH-NH/química , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Poliaminas/metabolismo , Zea mays/enzimologia , Catálise , Cristalografia por Raios X , Oxirredução , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Proteínas de Plantas/genética , Estrutura Secundária de Proteína , Espermidina/metabolismo , Espermina/metabolismo , Poliamina OxidaseRESUMO
Spermine oxidase (SMO) and acetylpolyamine oxidase (APAO) are FAD-dependent enzymes that are involved in the highly regulated pathways of polyamine biosynthesis and degradation. Polyamine content is strictly related to cell growth, and dysfunctions in polyamine metabolism have been linked with cancer. Specific inhibitors of SMO and APAO would allow analyzing the precise role of these enzymes in polyamine metabolism and related pathologies. However, none of the available polyamine oxidase inhibitors displays the desired characteristics of selective affinity and specificity. In addition, repeated efforts to obtain structural details at the atomic level on these two enzymes have all failed. In the present study, in an effort to better understand structure-function relationships, SMO enzyme-substrate complex has been probed through a combination of molecular modeling, site-directed mutagenesis and biochemical studies. Results obtained indicate that SMO binds spermine in a similar conformation as that observed in the yeast polyamine oxidase FMS1-spermine complex and demonstrate a major role for residues His82 and Lys367 in substrate binding and catalysis. In addition, the SMO enzyme-substrate complex highlights the presence of an active site pocket with highly polar characteristics, which may explain the different substrate specificity of SMO with respect to APAO and provide the basis for the design of specific inhibitors for SMO and APAO.