Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 101
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
ACS Appl Mater Interfaces ; 16(23): 29621-29633, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38806169

RESUMO

The ongoing challenge of viral transmission, exemplified by the Covid pandemic and recurrent viral outbreaks, necessitates the exploration of sustainable antiviral solutions. This study investigates the underexplored antiviral potential of wooden surfaces. We evaluated the antiviral efficacy of various wood types, including coniferous and deciduous trees, against enveloped coronaviruses and nonenveloped enteroviruses like coxsackie virus A9. Our findings revealed excellent antiviral activity manifesting already within 10 to 15 min in Scots pine and Norway spruce, particularly against enveloped viruses. In contrast, other hardwoods displayed varied efficacy, with oak showing effectiveness against the enterovirus. This antiviral activity was consistently observed across a spectrum of humidity levels (20 to 90 RH%), while the antiviral efficacy manifested itself more rapidly at 37 °C vs 21 °C. Key to our findings is the chemical composition of these woods. Resin acids and terpenes were prevalent in pine and spruce, correlating with their antiviral performance, while oak's high phenolic content mirrored its efficacy against enterovirus. The pine surface absorbed a higher fraction of the coronavirus in contrast to oak, whereas enteroviruses were not absorbed on those surfaces. Thermal treatment of wood or mixing wood with plastic, such as in wood-plastic composites, strongly compromised the antiviral functionality of wood materials. This study highlights the role of bioactive chemicals in the antiviral action of wood and opens new avenues for employing wood surfaces as a natural and sustainable barrier against viral transmissions.


Assuntos
Antivirais , Enterovirus , Madeira , Madeira/química , Antivirais/química , Antivirais/farmacologia , Enterovirus/efeitos dos fármacos , Coronavirus/efeitos dos fármacos , Inativação de Vírus/efeitos dos fármacos , Propriedades de Superfície , Quercus/química , Humanos , Pinus/química , Picea/química , Árvores/virologia
2.
ACS Omega ; 9(15): 17089-17096, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38645339

RESUMO

In the development of proteins, aptamers, and molecular imprints for diagnostic purposes, a major goal is to obtain a molecule with both a high binding affinity and specificity for the target ligand. Cushing syndrome or Addison's disease can be diagnosed by cortisol level tests. We have previously characterized and solved the crystal structure of an anti-cortisol (17) Fab fragment having a high affinity to cortisol but also significant cross-reactivity to other glucocorticoids, especially the glucocorticoid drug prednisolone. We used native mass spectrometry (MS) to determine the binding affinities of nine steroid hormones to anti-cortisol (17) Fab, including steroidogenic precursors of cortisol. Based on the results, the number of hydroxyl groups in the structure of a steroid ligand plays a key role in the antigen recognition by the Fab fragment as the ligands with three hydroxyl groups, cortisol and prednisolone, had the highest affinities. The antibody affinity toward steroid hormones often decreases with a decrease in the number of hydroxyl groups in the structure. The presence of the hydroxyl group at position C11 increased the affinity more than did the other hydroxyl groups at positions C17 or C21. The binding affinities obtained by native MS were compared to the values determined by surface plasmon resonance (SPR), and the affinities were found to correlate well between these two techniques. Our study demonstrates that native MS with a large dynamic range and high sensitivity is a versatile tool for ligand binding studies of proteins.

3.
ACS Omega ; 9(8): 9443-9451, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38434869

RESUMO

Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, coupled with electrospray ionization (ESI) or atmospheric-pressure photoionization (APPI), was employed for chemical fingerprinting of baijiu, a traditional Chinese liquor. Baijiu is the most consumed distilled alcoholic beverage globally, with over 10 billion liters sold annually. It is a white (transparent) spirit that exhibits similarities to dark spirits such as whisky or rum in terms of aroma and mouthfeel. In this study, direct-infusion FT-ICR mass spectrometry was used to analyze 10 commercially available baijiu liquors, enabling the examination of both volatile and nonvolatile constituents without the need for tedious sample extractions or compound derivatizations. The chemical fingerprints obtained by FT-ICR MS revealed substantial compositional diversity among different baijiu liquors, reflecting variations in the raw materials and production methods. The main compounds identified included a variety of acids, esters, aldehydes, lactones, terpenes, and phenolic compounds. The use of ESI and APPI provided complementary compositional information; while ESI demonstrated greater selectivity toward polar, aliphatic sample constituents, APPI also ionized semipolar and nonpolar (aromatic) ones.

4.
FEBS J ; 291(3): 510-526, 2024 02.
Artigo em Inglês | MEDLINE | ID: mdl-37863644

RESUMO

Hydroxymethylbilane synthase (HMBS), involved in haem biosynthesis, catalyses the head-to-tail coupling of four porphobilinogens (PBGs) via a dipyrromethane (DPM) cofactor. DPM is composed of two PBGs, and a hexapyrrole is built before the tetrapyrrolic 1-hydroxymethylbilane product is released. During this elongation, stable enzyme (E) intermediates are formed from the holoenzyme, with additional PBG substrates (S): ES, ES2 , ES3 and ES4 . Native PAGE and mass spectrometry of the acute intermittent porphyria (AIP)-associated HMBS variant p.Arg167Gln demonstrated an increased amount of ES3 . Kinetic parameters indicated catalytic dysfunction, however, the product release was not entirely prevented. Isolation and crystal structure analysis of the ES3 intermediate (PDB: 8PND) showed that a pentapyrrole was fully retained within the active site, revealing that polypyrrole elongation proceeds within the active site via a third interaction site, intermediate pyrrole site 3 (IPS3). The AIP-associated HMBS variant p.Arg195Cys, located on the opposite side to p.Arg167Gln in the active site, accumulated the ES4 intermediate in the presence of excess PBG, implying that product hydrolysis was obstructed. Arg167 is thus involved in all elongation steps and is a determinant for the rate of enzyme catalysis, whereas Arg195 is important for releasing the product. Moreover, by substituting residues in the vicinity of IPS3, our results indicate that a fully retained hexapyrrole could be hydrolysed in a novel site in proximity of the IPS3.


Assuntos
Hidroximetilbilano Sintase , Porfiria Aguda Intermitente , Humanos , Hidroximetilbilano Sintase/química , Hidroximetilbilano Sintase/genética , Hidroximetilbilano Sintase/metabolismo , Polímeros , Pirróis , Domínio Catalítico , Mutação
5.
Enzyme Microb Technol ; 169: 110265, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37269617

RESUMO

Unnatural amino acids are unique building blocks in modern medicinal chemistry as they contain an amino and a carboxylic acid functional group, and a variable side chain. Synthesis of pure unnatural amino acids can be made through chemical modification of natural amino acids or by employing enzymes that can lead to novel molecules used in the manufacture of various pharmaceuticals. The NAD+ -dependent alanine dehydrogenase (AlaDH) enzyme catalyzes the conversion of pyruvate to L-alanine by transferring ammonium in a reversible reductive amination activity. Although AlaDH enzymes have been widely studied in terms of oxidative deamination activity, reductive amination activity studies have been limited to the use of pyruvate as a substrate. The reductive amination potential of heterologously expressed, highly pure Thermomicrobium roseum alanine dehydrogenase (TrAlaDH) was examined with regard to pyruvate, α-ketobutyrate, α-ketovalerate and α-ketocaproate. The biochemical properties were studied, which included the effects of 11 metal ions on enzymatic activity for both reactions. The enzyme accepted both derivatives of L-alanine (in oxidative deamination) and pyruvate (in reductive amination) as substrates. While the kinetic KM values associated with the pyruvate derivatives were similar to pyruvate values, the kinetic kcat values were significantly affected by the side chain increase. In contrast, KM values associated with the derivatives of L-alanine (L-α-aminobutyrate, L-norvaline, and L-norleucine) were approximately two orders of magnitude greater, which would indicate that they bind very poorly in a reactive way to the active site. The modeled enzyme structure revealed differences in the molecular orientation between L-alanine/pyruvate and L-norleucine/α-ketocaproate. The reductive activity observed would indicate that TrAlaDH has potential for the synthesis of pharmaceutically relevant amino acids.


Assuntos
Alanina Desidrogenase , Aminoácido Oxirredutases , Alanina Desidrogenase/genética , Alanina Desidrogenase/metabolismo , Aminoácido Oxirredutases/genética , Aminoácido Oxirredutases/metabolismo , Aminação , Alanina , Aminoácidos/metabolismo , Ácido Pirúvico , Especificidade por Substrato
6.
J Agric Food Chem ; 71(18): 7082-7089, 2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-37103967

RESUMO

Gin is one of the most consumed distilled alcoholic spirits worldwide, with more than 400 million liters sold every year. It is most often produced through redistillation of agricultural ethanol in the presence of botanicals, most notably juniper berries, which give gin its characteristic flavor. Due to its natural ingredients, gin is a complex mixture of hundreds of volatile and nonvolatile chemical constituents. In this work, ultrahigh-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry was used for the compositional analysis of 16 commercially produced gins. Two complementary ionization methods, namely, electrospray ionization (ESI) and atmospheric-pressure photoionization (APPI), were employed to cover a wider compositional space. Each gin provided unique chemical fingerprints by ESI and APPI, which allowed semiquantitative analysis of 135 tentatively identified compounds, including terpene hydrocarbons, terpenoids, phenolics, fatty acids, aldehydes, and esters. Most of these compounds have not been previously reported in gins. While chemical fingerprints were rather similar between most products, some products contained unique compounds due to their special natural ingredients or the production methods applied. For instance, a barrel-matured gin contained a high content of syringaldehyde and sinapaldehyde, which are typical phenolic aldehydes originated from oak wood. In addition, the relative abundance of vanillin, vanillic acid, gallic acid, coniferyl aldehyde, and syringaldehyde was clearly higher than in the other gin samples. Ultrahigh-resolution FT-ICR MS serves as a powerful tool for direct chemical fingerprinting of gin or any other distilled spirit, which can be used for rapid product quality screening, product optimization, or possible counterfeit product discovery.


Assuntos
Pressão Atmosférica , Misturas Complexas , Espectrometria de Massas/métodos , Misturas Complexas/química , Etanol , Espectrometria de Massas por Ionização por Electrospray/métodos , Análise de Fourier
7.
Int J Biol Macromol ; 239: 124229, 2023 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-36990412

RESUMO

Major proteins of the seminal plasma in a variety of mammals such as bovine PDC-109, equine HSP-1/2, and donkey DSP-1 contain fibronectin type-II (FnII) domains and are referred to as FnII family proteins. To further our understanding on these proteins, we carried out detailed studies on DSP-3, another FnII protein of donkey seminal plasma. High-resolution mass-spectrometric studies revealed that DSP-3 contains 106 amino acid residues and is heterogeneously glycosylated with multiple acetylations on the glycans. Interestingly, high homology was observed between DSP-1 and HSP-1 (118 identical residues) than between DSP-1 and DSP-3 (72 identical residues). Circular dichroism (CD) spectroscopic and differential scanning calorimetric (DSC) studies showed that DSP-3 unfolds at ~45 °C and binding of phosphorylcholine (PrC) - the head group moiety of choline phospholipids - increases the thermal stability. Analysis of DSC data suggested that unlike PDC-109 and DSP-1, which exist as mixtures of polydisperse oligomers, DSP-3 most likely exists as a monomer. Ligand binding studies monitoring changes in protein intrinsic fluorescence indicated that DSP-3 binds lyso-phosphatidylcholine (Ka = 1.08 × 105 M-1) with ~80-fold higher affinity than PrC (Ka = 1.39 × 103 M-1). Binding of DSP-3 to erythrocytes leads to membrane perturbation, suggesting that its binding to sperm plasma membrane could be physiologically significant.


Assuntos
Equidae , Sêmen , Animais , Cavalos , Bovinos , Masculino , Sêmen/metabolismo , Ligação Proteica , Glicoproteínas/metabolismo , Fosforilcolina , Fosfatidilcolinas , Proteínas de Plasma Seminal/metabolismo
8.
ACS Sustain Chem Eng ; 11(4): 1540-1547, 2023 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-36743392

RESUMO

Coniferous trees are the most dominant trees in Finland with a great economic value for pulp, paper, and timber making. Thus, their utilization also results in large quantities of residues, especially bark and needles. Tree needles are a rich source of bioactive compounds, which have a considerable utilization potential in different pharmaceutical or techno-chemical applications. In this study, hydrothermal extraction (HTE) of the needles from four conifer tree species, namely, Scots pine, Norway spruce, common juniper, and European larch, was performed. Besides water, ethanol was also used as a solvent to enhance extraction efficiency and selectivity. All of the HTE experiments were conducted with a customized high-pressure reactor operated at 120 °C and 5 bar. The obtained needle extracts were then analyzed using a direct-infusion ultrahigh-resolution Fourier transform ion cyclotron (FT-ICR) mass spectrometry. The FT-ICR analysis of water and ethanol extracts allowed identification of over 200 secondary plant metabolites, including monosaccharides, organic acids, terpenoids, a variety of phenolic compounds, and nitrogen alkaloids. The use of ethanol as the extraction solvent considerably enhanced the recovery of lipids, especially terpenoids, some polyphenols, and other unsaturated hydrocarbon species.

9.
Inorg Chem ; 61(48): 19220-19231, 2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36414241

RESUMO

The phosphonium-decorated phenanthro-imidazolyl pyridine ligand, LP+Br, readily reacts with zinc(II) and cadmium(II) bromides to give inorganic-organic zero-dimensional compounds [LP+ZnBr2]2[ZnBr4] (1) and [(LP+)2Cd2Br4][CdBr4] (2), respectively, upon crystallization. These salts are moderately fluorescent in the solid state under ambient conditions (λem = 458 nm, Φem = 0.11 for 1; λem = 460 nm, Φem = 0.13 for 2). Their emission results from spin-allowed electronic transitions localized on the organic component with the negligible effect of [MBr4]2- and MBr2 units. Contrary to ionic species 1 and 2, lead(II) bromide affords a neutral and water-stable complex [(LP+)2Pb3Br8] (3), showing weak room-temperature phosphorescence arising from spin-orbit coupling due to the heavy atom effect. The emission, which is substantially enhanced for the amorphous sample of 3 (λem = 575 nm, Φem = 0.06), is assigned to the intraligand triplet excited state, which is a rare phenomenon among Pb(II) molecular materials.

10.
J Biol Chem ; 298(12): 102614, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36265586

RESUMO

Collagen prolyl 4-hydroxylases (C-P4H) are α2ß2 tetramers, which catalyze the prolyl 4-hydroxylation of procollagen, allowing for the formation of the stable triple-helical collagen structure in the endoplasmic reticulum. The C-P4H α-subunit provides the N-terminal dimerization domain, the middle peptide-substrate-binding (PSB) domain, and the C-terminal catalytic (CAT) domain, whereas the ß-subunit is identical to the enzyme protein disulfide isomerase (PDI). The structure of the N-terminal part of the α-subunit (N-terminal region and PSB domain) is known, but the structures of the PSB-CAT linker region and the CAT domain as well as its mode of assembly with the ß/PDI subunit, are unknown. Here, we report the crystal structure of the CAT domain of human C-P4H-II complexed with the intact ß/PDI subunit, at 3.8 Å resolution. The CAT domain interacts with the a, b', and a' domains of the ß/PDI subunit, such that the CAT active site is facing bulk solvent. The structure also shows that the C-P4H-II CAT domain has a unique N-terminal extension, consisting of α-helices and a ß-strand, which is the edge strand of its major antiparallel ß-sheet. This extra region of the CAT domain interacts tightly with the ß/PDI subunit, showing that the CAT-PDI interface includes an intersubunit disulfide bridge with the a' domain and tight hydrophobic interactions with the b' domain. Using this new information, the structure of the mature C-P4H-II α2ß2 tetramer is predicted. The model suggests that the CAT active-site properties are modulated by α-helices of the N-terminal dimerization domains of both subunits of the α2-dimer.


Assuntos
Prolil Hidroxilases , Isomerases de Dissulfetos de Proteínas , Humanos , Domínio Catalítico , Colágeno/metabolismo , Peptídeos/metabolismo , Pró-Colágeno-Prolina Dioxigenase/metabolismo , Prolil Hidroxilases/metabolismo , Isomerases de Dissulfetos de Proteínas/metabolismo , Conformação Proteica
11.
Protein J ; 41(4-5): 489-503, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35947329

RESUMO

Carbonic anhydrases (CA, EC 4.2.1.1) catalyze the hydration of carbon dioxide and take part in many essential physiological processes. In humans, 15 CAs are characterized, including the only secreted isoenzyme CA VI. CA VI has been linked to specific processes in the mouth, namely bitter taste perception, dental caries, and maintenance of enamel pellicle, and implicated in several immunity-related phenomena. However, little is known of the mechanisms of the above. In this study, we characterized human CA VI purified from saliva and milk with biophysical methods and measured their enzyme activities and acetazolamide inhibition. Size-exclusion chromatography showed peaks of salivary and milk CA VI corresponding to hexameric state or larger at pH 7.5. At pH 5.0 the hexamer peaks dominated. SDS- PAGE of milk CA VI protein treated with a bifunctional crosslinker further confirmed that a majority of CA VI is oligomers of similar sizes in solution. Mass spectrometry experiments confirmed that both of the two putative N-glycosylation sites, Asn67 and Asn256, are heterogeneously glycosylated. The attached glycans in milk CA VI were di- and triantennary complex-type glycans, carrying both a core fucose and 1 to 2 additional fucose units, whereas the glycans in salivary CA VI were smaller, seemingly degraded forms of core fucosylated complex- or hybrid-type glycans. Mass spectrometry also verified the predicted signal peptide cleavage site and the terminal residue, Gln 18, being in pyroglutamate form. Thorough characterization of CA VI paves way to better understanding of the biological function of the protein.


Assuntos
Anidrases Carbônicas , Leite Humano , Saliva , Anidrases Carbônicas/análise , Fucose , Humanos , Leite Humano/enzimologia , Saliva/enzimologia
12.
ACS Omega ; 7(12): 10789-10795, 2022 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-35382263

RESUMO

A set of simulation applets has been developed for visualizing the behavior of the association and dissociation reactions in protein studies. These reactions are simple equilibrium reactions, and the equilibrium constants, most often dissociation constant K D, are useful measures of affinity. Equilibria, even in simple systems, may not behave intuitively, which can cause misconceptions and mistakes. These applets can be utilized for planning experiments, for verifying experimental results, and for visualization of the equilibria in education. The considered reactions include protein homodimerization, ligand binding to a receptor (or heterodimerization), and competitive ligand binding. The latter one can be considered as either a ligand binding to two receptors or a binding of two ligands to a single receptor. In general, the user is required to input the total concentrations of all proteins and ligands and the dissociation constants of all complexes, and the applets output the equilibrium concentrations of all protein species graphically as functions of concentration and as numerical values at a specified point. Also, a curve fitting tool is provided which roughly estimates the concentrations or the dissociation constants based on the experimental data. The applets are freely available online (URL: https://protsim.github.io/protsim) and readily hackable for custom purposes if necessary.

13.
Food Chem ; 383: 132303, 2022 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-35196582

RESUMO

Chemical fingerprinting of phenolic compounds present in Finnish berry wines was performed using a direct-infusion Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The main aim of this study was to compare the phenolics profiles of wines produced from natural and/or cultivated berries and to demonstrate the feasibility of FT-ICR MS for a direct chemical analysis of the wine samples without chromatographic separation. First, phenolic compounds were recovered from the wine samples by solid-phase extraction (SPE), and the total phenolic content (TPC) was then determined by a Folin-Ciocalteau assay. The TPC of the original berry wines varied from 421 to 2108 mg/L, while the TPC of the extracts was 157-1525 mg/L. Over fifty phenolic compounds were tentatively identified from the wine samples by FT-ICR MS, whose concentrations highly varied depending on the types of berries used in the winemaking process.


Assuntos
Vinho , Ciclotrons , Finlândia , Análise de Fourier , Frutas/química , Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas/métodos , Fenóis/análise , Vinho/análise
14.
Int J Biol Macromol ; 194: 213-222, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34863837

RESUMO

Fibronectin type-II (FnII) family proteins are the major proteins in many mammalian species including bull, horse and pig. In the present study, a major FnII protein has been identified and isolated from donkey (Equus hemionus) seminal plasma, which we refer to as Donkey Seminal Plasma protein-1 (DSP-1). The amino acid sequence determined by mass spectrometry and computational modeling studies revealed that DSP-1 is homologous to other mammalian seminal plasma proteins, including bovine PDC-109 (also known as BSP-A1/A2) and equine HSP-1/2. High-resolution LC-MS analysis indicated that the protein is heterogeneously glycosylated and also contains multiple acetylations, occurring in the attached glycans. Structural and thermal stability studies on DSP-1 employing CD spectroscopy and differential scanning calorimetry showed that the protein unfolds at ~43 °C and binding to phosphorylcholine (PrC) - the head group moiety of choline phospholipids - increases its thermal stability. Intrinsic fluorescence titrations revealed that DSP-1 recognizes lyso-phosphatidylcholine with over 100-fold higher affinity than PrC. Further, interaction of DSP-1 with erythrocytes, a model cell membrane, revealed that DSP-1 binding is mediated by a specific interaction with choline phospholipids and results in membrane perturbation, suggesting that binding of this protein to sperm plasma membrane could be physiologically significant.


Assuntos
Equidae , Proteínas de Plasma Seminal/química , Proteínas de Plasma Seminal/isolamento & purificação , Animais , Fenômenos Químicos , Cromatografia de Afinidade , Ligantes , Espectrometria de Massas , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Proteínas de Plasma Seminal/metabolismo , Análise Espectral
15.
Phytochem Anal ; 33(3): 392-401, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34766378

RESUMO

INTRODUCTION: Coniferous trees, especially their needles and bark, are a rich source of bioactive compounds. The developing needles of Norway spruce (Picea abies), also known as spruce sprouts, are enriched with vitamin C and other antioxidants, and thus they are used as a dietary supplement and have been traditionally used to treat various inflammatory disorders such as rheumatism and gout. Their chemical composition is only limitedly known, however. OBJECTIVES: The main objective of this work was to have a deeper understanding on the chemical composition of spruce sprouts to assess their full potential in different pharmaceutical, nutraceutical, or technochemical applications. MATERIALS AND METHODS: Ultrahigh-resolution Fourier-transform ion cyclotron (FT-ICR) mass spectrometry, coupled to direct-infusion electrospray ionisation (ESI) or atmospheric pressure photoionisation (APPI) techniques, was used for in-depth compositional analysis of solvent extracts and essential oil of spruce sprouts. RESULTS: A combined use of ESI and APPI techniques offered a great complementary insight into the rich chemistry of different spruce sprout extracts, allowing detection of thousands of chemical constituents with over 200 secondary metabolites tentatively identified. These compounds belonged to different classes such as organic acids, terpenes, flavonoids, stilbenes, sterols, and nitrogen alkaloids. CONCLUSION: Spruce sprouts have a complex metabolite profile that differs considerably from that of the old, developed needles.


Assuntos
Óleos Voláteis , Picea , Espectrometria de Massas , Picea/química , Picea/metabolismo , Solventes , Terpenos/análise
16.
Biochemistry ; 60(41): 3046-3049, 2021 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-34633186

RESUMO

Caulobacter crescentus xylonolactonase (Cc XylC, EC 3.1.1.68) catalyzes an intramolecular ester bond hydrolysis over a nonenzymatic acid/base catalysis. Cc XylC is a member of the SMP30 protein family, whose members have previously been reported to be active in the presence of bivalent metal ions, such as Ca2+, Zn2+, and Mg2+. By native mass spectrometry, we studied the binding of several bivalent metal ions to Cc XylC and observed that it binds only one of them, namely, the Fe2+ cation, specifically and with a high affinity (Kd = 0.5 µM), pointing out that Cc XylC is a mononuclear iron protein. We propose that bivalent metal cations also promote the reaction nonenzymatically by stabilizing a short-lived bicyclic intermediate on the lactone isomerization reaction. An analysis of the reaction kinetics showed that Cc XylC complexed with Fe2+ can speed up the hydrolysis of d-xylono-1,4-lactone by 100-fold and that of d-glucono-1,5-lactone by 10-fold as compared to the nonenzymatic reaction. To our knowledge, this is the first discovery of a nonheme mononuclear iron-binding enzyme that catalyzes an ester bond hydrolysis reaction.


Assuntos
Proteínas de Bactérias/química , Hidrolases de Éster Carboxílico/química , Caulobacter crescentus/enzimologia , Proteínas de Bactérias/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Gluconatos/química , Hidrólise , Ferro/química , Ferro/metabolismo , Cinética , Lactonas/química , Espectrometria de Massas/métodos , Ligação Proteica
17.
IUCrJ ; 8(Pt 5): 757-774, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34584737

RESUMO

Mycobacterium tuberculosis (Mtb), which is responsible for more than a million deaths annually, uses lipids as the source of carbon and energy for its survival in the latent phase of infection. Mtb cannot synthesize all of the lipid molecules required for its growth and pathogenicity. Therefore, it relies on transporters such as the mammalian cell entry (Mce) complexes to import lipids from the host across the cell wall. Despite their importance for the survival and pathogenicity of Mtb, information on the structural properties of these proteins is not yet available. Each of the four Mce complexes in Mtb (Mce1-4) comprises six substrate-binding proteins (SBPs; MceA-F), each of which contains four conserved domains (N-terminal transmembrane, MCE, helical and C-terminal unstructured tail domains). Here, the properties of the various domains of Mtb Mce1A and Mce4A, which are involved in the import of mycolic/fatty acids and cholesterol, respectively, are reported. In the crystal structure of the MCE domain of Mce4A (MtMce4A39-140) a domain-swapped conformation is observed, whereas solution studies, including small-angle X-ray scattering (SAXS), indicate that all Mce1A and Mce4A domains are predominantly monomeric. Further, structural comparisons show interesting differences from the bacterial homologs MlaD, PqiB and LetB, which form homohexamers when assembled as functional transporter complexes. These data, and the fact that there are six SBPs in each Mtb mce operon, suggest that the MceA-F SBPs from Mce1-4 may form heterohexamers. Also, interestingly, the purification and SAXS analysis showed that the helical domains interact with the detergent micelle, suggesting that when assembled the helical domains of MceA-F may form a hydrophobic pore for lipid transport, as observed in EcPqiB. Overall, these data highlight the unique structural properties of the Mtb Mce SBPs.

18.
Adv Sci (Weinh) ; 8(20): e2102788, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34414696

RESUMO

The encapsulation and/or surface modification can stabilize and protect the phosphorescence bio-probes but impede their intravenous delivery across biological barriers. Here, a new class of biocompatible rhenium (ReI ) diimine carbonyl complexes is developed, which can efficaciously permeate normal vessel walls and then functionalize the extravascular collagen matrixes as in situ oxygen sensor. Without protective agents, ReI -diimine complex already exhibits excellent emission yield (34%, λem   = 583 nm) and large two-photon absorption cross-sections (σ2   = 300 GM @ 800 nm) in water (pH 7.4). After extravasation, remarkably, the collagen-bound probes further enhanced their excitation efficiency by increasing the deoxygenated lifetime from 4.0 to 7.5 µs, paving a way to visualize tumor hypoxia and tissue ischemia in vivo. The post-extravasation functionalization of extracellular matrixes demonstrates a new methodology for biomaterial-empowered phosphorescence sensing and imaging.


Assuntos
Vasos Sanguíneos/diagnóstico por imagem , Colágeno/metabolismo , Substâncias Luminescentes/farmacologia , Oxigênio/metabolismo , Vasos Sanguíneos/efeitos dos fármacos , Vasos Sanguíneos/metabolismo , Vasos Sanguíneos/patologia , Colágeno/genética , Humanos , Irídio/farmacologia , Microscopia Confocal , Neoplasias/genética , Neoplasias/patologia , Fótons , Rênio/química , Hipóxia Tumoral/genética , Microambiente Tumoral/efeitos dos fármacos , Microambiente Tumoral/genética
19.
Molecules ; 26(11)2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34070676

RESUMO

This study assessed the pyrolysis liquids obtained by slow pyrolysis of industrial hemp leaves, hurds, and roots. The liquids recovered between a pyrolysis temperature of 275-350 °C, at two condensation temperatures 130 °C and 70 °C, were analyzed. Aqueous and bio-oil pyrolysis liquids were produced and analyzed by proton nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS). NMR revealed quantitative concentrations of the most abundant compounds in the aqueous fractions and compound groups in the oily fractions. In the aqueous fractions, the concentration range of acetic acid was 50-241 gL-1, methanol 2-30 gL-1, propanoic acid 5-20 gL-1, and 1-hydroxybutan-2-one 2 gL-1. GC-MS was used to compare the compositions of the volatile compounds and APPI FT-ICR MS was utilized to determine the most abundant higher molecular weight compounds. The different obtained pyrolysis liquids (aqueous and oily) had various volatile and nonvolatile compounds such as acetic acid, 2,6-dimethoxyphenol, 2-methoxyphenol, and cannabidiol. This study provides a detailed understanding of the chemical composition of pyrolysis liquids from different parts of the industrial hemp plant and assesses their possible economic potential.


Assuntos
Cannabis/química , Folhas de Planta/química , Raízes de Plantas/química , Cromatografia Gasosa-Espectrometria de Massas , Espectrometria de Massas/métodos , Espectroscopia de Prótons por Ressonância Magnética/métodos , Pirólise , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
20.
Waste Manag ; 128: 36-44, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33962155

RESUMO

The pyrolysis of scrap tires is a very attractive strategy to valorize chemically these end-of-life wastes. The products of this step and any additional one, such as hydrotreating, are relatively complex in nature entangling the understanding and limiting the viability. In this work, we have investigated in detail the composition of a tire pyrolysis oil blended with light cycle oil (from a refinery) and its hydrotreated products using a bifunctional NiW/HY catalyst at 320-400 °C. We have applied a set of analytical techniques to assess the composition, namely simulated distillation, ICP, GC/FID-PFPD, GC × GC/MS, and APPI FT-ICR/MS. Our results show the strength of our analytical workflow to highlight the compositional similarities of this pyrolysis oil with the standard refinery streams. The main differences arise from the higher boiling point species (originated during the pyrolysis of tires) and relatively high concentration of oxygenates. These effects can be minimized by hydrotreating the feed which effectively removes heteroatomic compounds from the feed while boosting the quantity and quality of gasoline and diesel fractions.


Assuntos
Fotoperíodo , Pirólise , Catálise , Cromatografia Gasosa-Espectrometria de Massas , Gasolina/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA