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1.
Food Chem ; 356: 129720, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-33831834

RESUMO

The residue of doxycycline in food can cause harm to human. Therefore, the detection of doxycycline residue is necessary. Herein, a ratiometric fluorescent probe was designed based on sulfur quantum dots (S dots) and Ca2+. Due to static quenching and inter filter effect between doxycycline and S dots, doxycycline quenched fluorescence of S dots at 450 nm. Meanwhile, doxycycline and Ca2+ formed fluorescent complex through coordination to produce new peak at 520 nm. The ratio of fluorescence intensity (F520/F450) and doxycycline concentration showed good linear relationship with detection limit of 0.19 µM. The fluorescence color of S dots/Ca2+ changed from blue to light green with increasing doxycycline concentration, which was applied for visual semi-quantitative detection of doxycycline. Moreover, the method was used for detecting doxycycline in milk and fish samples with recoveries in the range of 91%-110%. The method showed good application potential in detection of doxycycline in food samples.


Assuntos
Cálcio/química , Doxiciclina/análise , Corantes Fluorescentes/química , Análise de Alimentos/métodos , Limite de Detecção , Pontos Quânticos/química , Enxofre/química , Animais , Doxiciclina/química , Contaminação de Alimentos/análise , Humanos , Leite/química , Espectrometria de Fluorescência
2.
J Med Chem ; 64(8): 4744-4761, 2021 04 22.
Artigo em Inglês | MEDLINE | ID: mdl-33822618

RESUMO

Spinal muscular atrophy (SMA) is a debilitating neuromuscular disease caused by low levels of functional survival motor neuron protein (SMN) resulting from a deletion or loss of function mutation of the survival motor neuron 1 (SMN1) gene. Branaplam (1) elevates levels of full-length SMN protein in vivo by modulating the splicing of the related gene SMN2 to enhance the exon-7 inclusion and increase levels of the SMN. The intramolecular hydrogen bond present in the 2-hydroxyphenyl pyridazine core of 1 enforces a planar conformation of the biaryl system and is critical for the compound activity. Scaffold morphing revealed that the pyridazine could be replaced by a 1,3,4-thiadiazole, which provided additional opportunities for a conformational constraint of the biaryl through intramolecular 1,5-sulfur-oxygen (S···O) or 1,5-sulfur-halogen (S···X) noncovalent interactions. Compound 26, which incorporates a 2-fluorophenyl thiadiazole motif, demonstrated a greater than 50% increase in production of full-length SMN protein in a mouse model of SMA.


Assuntos
Desenho de Fármacos , Splicing de RNA , Tiadiazóis/química , Animais , Meia-Vida , Halogênios/química , Humanos , Masculino , Camundongos , Conformação Molecular , Neurônios Motores/metabolismo , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/patologia , Oxigênio/química , Piridazinas/química , Splicing de RNA/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Enxofre/química , Proteína 1 de Sobrevivência do Neurônio Motor/genética , Proteína 1 de Sobrevivência do Neurônio Motor/metabolismo , Proteína 2 de Sobrevivência do Neurônio Motor/genética , Proteína 2 de Sobrevivência do Neurônio Motor/metabolismo , Tiadiazóis/metabolismo , Tiadiazóis/farmacologia
3.
Photochem Photobiol Sci ; 20(1): 183-188, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33721239

RESUMO

A hypothesis is proposed to explain the increased detrimental effect of COVID-19 for Black, Asian and Minority Ethnic (BAME) men and women compared to Caucasian individuals. This is based on the differing photochemistry of phaeomelanin in fair skin and eumelanin in dark/black skin. It is suggested that a range of reactive oxygen species, including, singlet oxygen and the superoxide radical anion, derived via direct photolysis of phaeomelanin, may escape the melanocyte and cause subsequent damage to the SARS-CoV-2 virus. It is further suggested that (large) carbon and sulphur peroxy radicals, from oxygen addition to radicals formed by carbon-sulphur bond cleavage, may assist via damage to the cell membranes. It is also speculated that light absorption by phaeomelanin and the subsequent C-S bond cleavage, leads to release of pre-absorbed reactive oxygen species, such as singlet oxygen and free radicals, which may also contribute to an enhanced protective effect for fair-skinned people.


Assuntos
COVID-19/patologia , Grupos Étnicos , Processos Fotoquímicos , COVID-19/etnologia , COVID-19/virologia , Carbono/química , Feminino , Radicais Livres/química , Humanos , Luz , Masculino , Melaninas/química , Fotólise , SARS-CoV-2/isolamento & purificação , Oxigênio Singlete/química , Oxigênio Singlete/metabolismo , Pele/metabolismo , Enxofre/química , Superóxidos/química , Superóxidos/metabolismo
4.
J Mol Biol ; 433(10): 166924, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33711344

RESUMO

The late-acting steps of the pathway responsible for the maturation of mitochondrial [4Fe-4S] proteins are still elusive. Three proteins ISCA1, ISCA2 and NFU1 were shown to be implicated in the assembly of [4Fe-4S] clusters and their transfer into mitochondrial apo proteins. We present here a NMR-based study showing a detailed molecular model of the succession of events performed in a coordinated manner by ISCA1, ISCA2 and NFU1 to make [4Fe-4S] clusters available to mitochondrial apo proteins. We show that ISCA1 is the key player of the [4Fe-4S] protein maturation process because of its ability to interact with both NFU1 and ISCA2, which, instead do not interact each other. ISCA1 works as the promoter of the interaction between ISCA2 and NFU1 being able to determine the formation of a transient ISCA1-ISCA2-NFU1 ternary complex. We also show that ISCA1, thanks to its specific interaction with the C-terminal cluster-binding domain of NFU1, drives [4Fe-4S] cluster transfer from the site where the cluster is assembled on the ISCA1-ISCA2 complex to a cluster binding site formed by ISCA1 and NFU1 in the ternary ISCA1-ISCA2-NFU1 complex. Such mechanism guarantees that the [4Fe-4S] cluster can be safely moved from where it is assembled on the ISCA1-ISCA2 complex to NFU1, thereby resulting the [4Fe-4S] cluster available for the mitochondrial apo proteins specifically requiring NFU1 for their maturation.


Assuntos
Apoproteínas/química , Proteínas de Transporte/química , Proteínas Ferro-Enxofre/química , Ferro/química , Mitocôndrias/química , Proteínas Mitocondriais/química , Enxofre/química , Apoproteínas/genética , Apoproteínas/metabolismo , Sítios de Ligação , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Células Eucarióticas/citologia , Células Eucarióticas/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Humanos , Ferro/metabolismo , Proteínas Ferro-Enxofre/genética , Proteínas Ferro-Enxofre/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Modelos Químicos , Ressonância Magnética Nuclear Biomolecular , Regiões Promotoras Genéticas , Ligação Proteica , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Enxofre/metabolismo
5.
Molecules ; 26(4)2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33562491

RESUMO

Fluoride anion was demonstrated as a superior activator of elemental sulfur (S8) to perform sulfurization of thioketones leading to diverse sulfur-rich heterocycles. Due to solubility problems, reactions must be carried out either in THF using tetrabutylammonium fluoride (TBAF) or in DMF using cesium fluoride (CsF), respectively. The reactive sulfurizing reagents are in situ generated, nucleophilic fluoropolysulfide anions FS(8-x)-, which react with the C=S bond according to the carbophilic addition mode. Dithiiranes formed thereby, existing in an equilibrium with the ring-opened form (diradicals/zwitterions) are key-intermediates, which undergo either a step-wise dimerization to afford 1,2,4,5-tetrathianes or an intramolecular insertion, leading in the case of thioxo derivatives of 2,2,4,4-tetramethylcyclobutane-1,3-dione to ring enlarged products. In reactions catalyzed by TBAF, water bounded to fluoride anion via H-bridges and forming thereby its stable hydrates is involved in secondary reactions leading, e.g., in the case of 2,2,4,4-tetramethyl-3-thioxocyclobutanone to the formation of some unexpected products such as the ring enlarged dithiolactone and ring-opened dithiocarboxylate. In contrast to thioketones, the fluoride anion catalyzed sulfurization of their α,ß-unsaturated analogues, i.e., thiochalcones is slow and inefficient. However, an alternative protocol with triphenylphosphine (PPh3) applied as a catalyst, offers an attractive approach to the synthesis of 3H-1,2-dithioles via 1,5-dipolar electrocyclization of the in situ-generated α,ß-unsaturated thiocabonyl S-sulfides. All reactions occur under mild conditions and can be considered as attractive methods for the preparation of sulfur rich heterocycles with diverse ring-size.


Assuntos
Chalconas/química , Fluoretos/química , Enxofre/química , Tionas/química , Catálise , Modelos Moleculares , Conformação Molecular
6.
Carbohydr Polym ; 257: 117618, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33541646

RESUMO

A strategy to optimize the labeling of the reducing end of native cellulose nanocrystals (CNCs) with gold nanoparticles (AuNPs) was developed and used to investigate the arrangement of the elementary crystallites constituting these biosourced particles. First, CNCs pre-functionalized with thiosemicarbazide molecules were reacted with presynthesized AuNPs. A second method consisted in synthesizing AuNPs in situ from soluble gold derivatives in the presence of CNCs regioselectively functionalized with thiosemicarbazide molecules. Transmission electron microscopy images revealed that the direct reaction resulted in a low labeling yield and the undesired formation of AuNP aggregates. Oppositely, unprecedent high labeling yields were achieved through the in situ growth approach, with a vast majority of CNCs bearing one or several AuNPs on one end. These results evidence that cotton-derived CNCs are composed of the unidirectional assembly of chemically polar elementary crystallites, implying that the acid hydrolysis isolates fragments of microfibril bundles present in the cell walls.


Assuntos
Celulose/química , Fibra de Algodão , Ouro/química , Nanopartículas Metálicas/química , Microfibrilas/química , Nanopartículas/química , Aldeídos/química , Parede Celular/metabolismo , Hidrólise , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Semicarbazidas/química , Enxofre/química , Madeira , Difração de Raios X
7.
Carbohydr Polym ; 257: 117632, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33541658

RESUMO

Since vascular diseases are regarded as a major cause of death worldwide, developing engineered biomimetic elastomers with physicochemical and biological properties resembling those of the natural vascular tissues, is vital for vascular tissue engineering (VTE). This study reports synthesis of highly tough supramolecular biologically active alginate-based supramolecular polyurethane (BASPU) elastomers that benefit from the presence of two physical networks with different strength of soft tertiary ammonium-soft sulfate pairs, as strong ionic bonds, and soft tertiary ammonium-hard carboxylate groups, as the weak bonds. The presence of sulfate groups resulted in low Young's modulus, high toughness and stretchability, proper energy dissipation, ultrafast self-healing and complete healing efficiency of BASPU. In vitro studies showed higher endothelial cells attachment, higher anticoagulation ability and significantly less platelet adhesion for BASPUs compared to the commercial vascular prosthesis. The histological studies of subcutaneously implanted scaffolds confirmed their low fibrosis and gradual biodegradation during 2 months of following.


Assuntos
Alginatos/química , Reagentes para Ligações Cruzadas/química , Elastômeros/química , Poliuretanos/química , Engenharia Tecidual/métodos , Compostos de Amônio/química , Anticoagulantes/química , Materiais Biocompatíveis , Cátions , Módulo de Elasticidade , Células Endoteliais , Células Endoteliais da Veia Umbilical Humana , Humanos , Íons , Teste de Materiais , Adesividade Plaquetária , Solventes , Enxofre/química , Resistência à Tração , Tecidos Suporte
8.
Yakugaku Zasshi ; 141(2): 215-233, 2021.
Artigo em Japonês | MEDLINE | ID: mdl-33518643

RESUMO

Studies on functional molecules starting from syntheses of cysteine-containing peptides and protein are described. Starting from evaluation of a cysteine specific side-reaction, a specific reaction for disulfide-bond formation was developed. The reaction made it possible to independently construct a disulfide bridge without effecting the existing disulfide bonds, which resulted in a unique approach for the synthesis of human insulin by site-specific disulfide bond formation. In a series of studies on sulfur-containing amino acids, another cysteine related un-natural amino acid, α-methyl cysteine, was used for the total syntheses of natural products containing a unique thiazorine/thiazole ring system. Chloroimidazolidium coupling reagent developed by us was effective for the successive couplings of the α-methyl cysteine residues. Based on these synthetic studies, design and evaluation of protease inhibitors were then studied, since a stereo-specific synthesis of the key structure is crucial to make the inhibitor an effective functional molecule in the interactions with its target protease. As the target proteases, ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) and chymotrypsin-like protease of severe acute respiratory syndrome (SARS 3CL protease) were selected: the former is a crucial enzyme for amyloid ß production and the latter is an essential enzyme for the re-construction of SARS corona virus in host cells. Structure optimization procedure of the respective inhibitors are described based on X-ray crystal structure analyses of the inhibitor-protease complex.


Assuntos
Aminoácidos/química , Peptídeos/síntese química , Secretases da Proteína Precursora do Amiloide/química , Ácido Aspártico Endopeptidases/química , Produtos Biológicos/síntese química , Produtos Biológicos/química , Quimases/química , Cristalografia por Raios X , Cisteína , Dissulfetos/química , Insulina/síntese química , Peptídeos/química , Inibidores de Proteases/síntese química , Inibidores de Proteases/química , Vírus da SARS , Enxofre/química , Tiazóis/química
9.
Biochimie ; 182: 166-176, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33444662

RESUMO

Selenium is a vital micronutrient in many organisms. While traces are required for microbial utilization, excess amounts are toxic; thus, selenium can be regarded as a biological double-edged sword. Selenium is chemically similar to the essential element sulfur, but curiously, evolution has selected the former over the latter for a subset of oxidoreductases. Enzymes involved in sulfur metabolism are less discriminate in terms of preventing selenium incorporation; however, its specific incorporation into selenoproteins reveals a highly discriminate process that is not completely understood. We have identified SclA, a NifS-like protein in the nosocomial pathogen, Enterococcus faecalis, and characterized its enzymatic activity and specificity for l-selenocysteine over l-cysteine. It is known that Asp-146 is required for selenocysteine specificity in the human selenocysteine lyase. Thus, using computational biology, we compared the bacterial and mammalian enzymes and identified His-100, an Asp-146 ortholog in SclA, and generated site-directed mutants in order to study the residue's potential role in the l-selenocysteine discrimination mechanism. The proteins were overexpressed, purified, and characterized for their biochemical properties. All mutants exhibited varying Michaelis-Menten behavior towards l-selenocysteine, but His-100 was not found to be essential for this activity. Additionally, l-cysteine acted as a competitive inhibitor of all enzymes with higher affinity than l-selenocysteine. Finally, we discovered that SclA exhibited low activity with l-cysteine as a poor substrate regardless of mutations. We conclude that His-100 is not required for l-selenocysteine specificity, underscoring the inherent differences in discriminatory mechanisms between bacterial NifS-like proteins and mammalian selenocysteine lyases.


Assuntos
Proteínas de Bactérias/química , Enterococcus faecalis/enzimologia , Liases/química , Selênio/química , Enxofre/química , Proteínas de Bactérias/metabolismo , Liases/metabolismo , Selênio/metabolismo , Especificidade por Substrato , Enxofre/metabolismo
10.
Food Chem ; 346: 128914, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33418410

RESUMO

The antioxidants sulfur dioxide (50 ppm) and ascorbic acid (100 ppm) were added to grapes soon after harvest at crushing. The chemical composition and sensory profile of Sauvignon Blanc, Pinot Gris and Chardonnay wines were examined, made from grapes collected at three different sites for each variety. With good antioxidant protection of the juices, reflected in low absorbances at 420 nm, remarkable increases in the polyfunctional mercaptans, 3-mercaptohexanol (3MH) and its acetate ester (3MHA), were seen in the wines. Moreover, high levels of these compounds were produced in the Pinot Gris and Chardonnay wines, equally high as with Sauvignon Blanc. The Pinot Gris wines maintained varietal characteristics in sensory profiles, even with high levels of polyfunctional mercaptans. When elemental sulfur was included with the grapes at crushing, extra increases in polyfunctional mercaptans were observed. However, this led to the production of unwanted reductive aroma compounds in some wines.


Assuntos
Antioxidantes/química , Odorantes/análise , Enxofre/química , Vinho/análise , Acetatos/análise , Hexanóis , Compostos de Sulfidrila/análise , Vitis
11.
Biochim Biophys Acta Bioenerg ; 1862(1): 148317, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-32980338

RESUMO

Among the thioredoxin superfamily of proteins, the observation that numerous glutaredoxins bind iron-sulphur (Fe/S) clusters is one of the more recent and major developments concerning their functional properties. Glutaredoxins are present in most organisms. All members of the class II subfamily (including most monothiol glutaredoxins), but also some members of the class I (mostly dithiol glutaredoxins) and class III (land plant-specific monothiol or dithiol glutaredoxins) are Fe/S proteins. In glutaredoxins characterised so far, the [2Fe2S] cluster is coordinated by two active-site cysteine residues and two molecules of non-covalently bound glutathione in homo-dimeric complexes bridged by the cluster. In contrast to dithiol glutaredoxins, monothiol glutaredoxins possess no or very little oxidoreductase activity, but have emerged as important players in cellular iron metabolism. In this review we summarise the recent developments of the most prominent Fe/S glutaredoxins in eukaryotes, the mitochondrial single domain monothiol glutaredoxin 5, the chloroplastic single domain monothiol glutaredoxin S14 and S16, the nuclear/cytosolic multi-domain monothiol glutaredoxin 3, and the mitochondrial/cytosolic dithiol glutaredoxin 2.


Assuntos
Glutarredoxinas , Proteínas Ferro-Enxofre , Doenças das Plantas , Proteínas de Plantas , Plantas/enzimologia , Glutarredoxinas/química , Glutarredoxinas/genética , Glutarredoxinas/metabolismo , Humanos , Ferro/química , Ferro/metabolismo , Proteínas Ferro-Enxofre/química , Proteínas Ferro-Enxofre/genética , Proteínas Ferro-Enxofre/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Relação Estrutura-Atividade , Enxofre/química , Enxofre/metabolismo
12.
Eur J Med Chem ; 213: 113070, 2021 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-33309162

RESUMO

The quinazolinone nucleus represents, among the class of fused heterocycles, a very important scaffold to obtain molecules with biological activities. A review of literature revealed how such kind of fused heterocycles, coming from natural or synthetic source, are associated with a wide range of biological activities. This review is mainly directed towards the 4-(3H)-quinazolinones N-3 substituted with a five membered heterocycle in which all the possible combinations of nitrogen, sulfur and oxygen atoms are present.


Assuntos
Quinazolinonas/química , Animais , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Anti-Inflamatórios/química , Anti-Inflamatórios/farmacologia , Anticonvulsivantes/química , Anticonvulsivantes/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Antioxidantes/química , Antioxidantes/farmacologia , Antituberculosos/química , Antituberculosos/farmacologia , Benzotiazóis/química , Broncodilatadores/química , Broncodilatadores/farmacologia , Humanos , Estrutura Molecular , Nitrogênio/química , Oxigênio/química , Quinazolinonas/farmacologia , Enxofre/química , Tiazóis/química
13.
Food Chem ; 338: 127785, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32798825

RESUMO

Patulin (PAT) contaminant causes severe food safety issue throughout apple industry. Although adsorption is the feasible approach to remove PAT, the limited adsorption capacity and separation difficulty of most adsorbent is the major drawback that remains to be overcome. Here GO-SH doped aerogel was prepared and used for removal PAT from apple juice. The intrinsic porous of the aerogel and abundant active sites including -COOH, -NH2 and -SH offered the PAT adsorption capacity of 24.75 µg/mg that superior to most reported adsorbents. Furthermore, it could reduce 89 ± 1.23% PAT in real apple juice without juice quality deterioration and cytotoxicity. Importantly, the aerogel with good mechanical strength and structure stability could endure the complex juice solution so that there was no any residue after convenient separation of the aerogel, which proved that the proposed aerogel was a promising adsorbent to be applied to apple juice industry for PAT removal.


Assuntos
Sucos de Frutas e Vegetais/análise , Grafite/química , Malus/química , Patulina/química , Patulina/isolamento & purificação , Enxofre/química , Adsorção , Contaminação de Alimentos/análise , Géis
14.
Molecules ; 25(24)2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-33322081

RESUMO

Selenium (Se) is an essential trace element, which represents an integral part of glutathione peroxidase and other selenoproteins involved in the protection of cells against oxidative damage. Selenomethionine (SeMet), selenocysteine (SeCys), and methylselenocysteine (MeSeCys) are the forms of Se that occur in living systems. Se-containing compounds have been found to reduce carcinogenesis of animal models, and dietary supplemental Se might decrease cancer risk. Se is mainly taken up by plant roots in the form of selenate via high-affinity sulfate transporters. Consequently, owing to the chemical similarity between Se and sulfur (S), the availability of S plays a key role in Se accumulation owing to competition effects in absorption, translocation, and assimilation. Moreover, naturally occurring S-containing compounds have proven to exhibit anticancer potential, in addition to other bioactivities. Therefore, it is important to understand the interaction between Se and S, which depends on Se/S ratio in the plant or/and in the growth medium. Brassicaceae (also known as cabbage or mustard family) is an important family of flowering plants that are grown worldwide and have a vital role in agriculture and populations' health. In this review we discuss the distribution and further interactions between S and Se in Brassicaceae and provide several examples of Se or Se/S biofortifications' experiments in brassica vegetables that induced the chemopreventive effects of these crops by enhancing the production of Se- or/and S-containing natural compounds. Extensive further research is required to understand Se/S uptake, translocation, and assimilation and to investigate their potential role in producing anticancer drugs.


Assuntos
Anticarcinógenos/química , Anticarcinógenos/farmacologia , Brassicaceae/química , Quimioprevenção , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Selênio/química , Enxofre/química , Animais , Humanos , Compostos de Selênio/química , Compostos de Selênio/farmacologia , Relação Estrutura-Atividade , Compostos de Enxofre/química , Compostos de Enxofre/farmacologia , Verduras
15.
Aquat Toxicol ; 227: 105592, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32891020

RESUMO

International shipping is responsible for the release of numerous contaminants to the air and the marine environment. In order to reduce airborne emissions, a global 0.5 % sulphur limit for marine fuels was implemented in January 2020. Recently, a new generation of so-called hybrid fuels that meet these new requirements have appeared on the market. Studies have shown that these fuels have physical properties that make conventional clean-up methods difficult, but few have studied their effects on marine life. We conducted short and long-term microcosm experiments with natural mesozooplankton communities exposed to the water accommodated fractions (WAFs) of the hybrid fuel RMD80 (0.1 % sulphur) and a Marine Gas Oil (MGO). We compared the toxicity of both fuel types in 48h short-term exposures, and studied the effects of the hybrid fuel on community structure over two generations in a 28-day experiment. The F0 generation was exposed for eight days and the F1 generation was raised for 22 days without exposure. GC-MS and GC-FID analysis of the WAFs revealed that the hybrid fuel was dominated by a mixture of volatile organic compounds (VOCs) and poly aromatic hydrocarbons (PAHs), whereas the MGO was mainly composed of VOCs. We observed significant short-term effects on copepod egg production from exposure to 25 % hybrid fuel WAF, but no effects from the MGO WAF at equivalent WAF dilution. In the long-term experiment with RMD80, the feeding rate was initially increased after exposure to 0.5-1.1 % hybrid fuel WAF, but this did not increase the copepod egg production. Significant change in community structure was observed after eight days in the F0 community at 0.5-3.3 % WAF. Indications of further alterations in species abundances was observed in the F1 community. Our results demonstrate that the MGO is a less toxic low-sulphur alternative to the hybrid fuel for marine zooplankton, and that a hybrid fuel spill could result in altered diversity of future generations of copepod communities.


Assuntos
Copépodes/efeitos dos fármacos , Óleos Combustíveis/toxicidade , Hidrocarbonetos Aromáticos/toxicidade , Enxofre/toxicidade , Poluentes Químicos da Água/toxicidade , Zooplâncton/efeitos dos fármacos , Animais , Copépodes/fisiologia , Relação Dose-Resposta a Droga , Óleos Combustíveis/análise , Hidrocarbonetos Aromáticos/química , Modelos Teóricos , Reprodução/efeitos dos fármacos , Navios , Enxofre/química , Fatores de Tempo , Poluentes Químicos da Água/química , Zooplâncton/fisiologia
16.
Nat Commun ; 11(1): 4170, 2020 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-32820174

RESUMO

Sulfur-sulfur motifs widely occur in vital function and drug design, which yearns for polysulfide construction in an efficient manner. However, it is a great challenge to install desired functional groups on both sides of sulfur-sulfur bonds at liberty. Herein, we designed a mesocyclic bilateral disulfurating reagent for sequential assembly and modular installation of polysulfides. Based on S-O bond dissociation energy imparity (mesocyclic compared to linear imparity is at least 5.34 kcal mol-1 higher), diverse types of functional molecules can be bridged via sulfur-sulfur bonds distinctly. With these stable reagents, excellent reactivities with nucleophiles including C, N and S are comprehensively demonstrated, sequentially installing on both sides of sulfur-sulfur motif with various substituents to afford six species of unsymmetrical polysulfides including di-, tri- and even tetra-sulfides. Life-related molecules, natural products and pharmaceuticals can be successively cross-linked with sulfur-sulfur bond. Remarkably, the cyclization of tri- and tetra-peptides affords 15- and 18-membered cyclic disulfide peptides with this reagent, respectively.


Assuntos
Dissulfetos/química , Indicadores e Reagentes/química , Peptídeos/química , Sulfetos/química , Enxofre/química , Produtos Biológicos/química , Técnicas de Química Sintética/métodos , Ciclização , Indicadores e Reagentes/síntese química , Modelos Químicos , Estrutura Molecular , Oxirredução , Preparações Farmacêuticas/química
17.
Met Ions Life Sci ; 202020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32851822

RESUMO

The number of transition metal ions which are essential to life - also often called trace elements - increased steadily over the years. In parallel, the list of biological functions in which transition metals are involved, has grown, and is still growing tremendously. Significant progress has been made in understanding the chemistry operating at the biological sites where metal ions have been discovered. Early on, based on the application of physical, chemical, and biological techniques, it became likely that numerous of these metal centers carry sulfur ligands in their coordination sphere, such as sulfide (S2-), cysteine (RS-), or methionine (RSCH3). Notably, the structure and the reactivity of the metal active sites turned out to be quite different from anything previously observed in simple coordination complexes. Consequently, the prediction of active-site structures, based on known properties of transition metal ion complexes, turned out to be difficult and incorrect in many cases. Yet, biomimetic inorganic chemistry, via synthesis and detailed structural and electronic characterization of synthetic analogues, became an important factor and helped to understand the properties of the metal active sites. Striking advances came from molecular biology techniques and protein crystallography, as documented by the publication of the first high-resolution structures of iron-sulfur proteins and the blue copper protein plastocyanin approximately five decades ago. In this volume of METAL IONS IN LIFE SCIENCES the focus will be on some of the most intriguing, in our view, transition metal-sulfur sites discovered in living organisms. These include the type 1 Cu mononuclear center, the purple mixed-valent [Cu1.5+-(Cys)2-Cu1.5+] CuA, the tetranuclear copper-sulfide catalytic center of nitrous oxide reductase, the heme-thiolate site in cytochrome P450, the iron-sulfur proteins with bound inorganic (S2-) and organic (Cys-) sulfur, the pterin dithiolene cofactor (Moco) coordinated to either molybdenum or tungsten, the [8Fe-7S] P-cluster and the [Mo-7Fe-9S-C]-homocitrate catalytic site of nitrogenase, the siroheme-[4Fe-4S] center involved in the reduction of sulfite (SO32-) to hydrogen sulfide (H2S), the NiFeS sites of hydrogenases and CO dehydrogenase, and the zinc finger domains. We apologize to all researchers and their associates who have made tremendous contributions to our current knowledge of the steadily increasing transition metal sulfur sites in proteins and enzymes but are not mentioned here. These omissions are by no means intentional but merely the consequence of time and space. We are fully aware of the excellent books and authoritative reviews on various aspects of the subject, however, it is our motivation to cover in one single volume this exciting domain of bioinorganic chemistry.


Assuntos
Enxofre/química , Hidrogenase , Proteínas Ferro-Enxofre , Molibdênio , Nitrogenase
18.
Met Ions Life Sci ; 202020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32851823

RESUMO

The non-metallic chemical element sulfur, 3216S , referred to in Genesis as brimstone and identified as element by Lavoisier, is the tenth most abundant element in the universe and the fifth most common element on Earth. Important inorganic forms of sulfur in the biosphere are elemental sulfur (S8), sulfate (SO2-4), and sulfide (S2-), sulfite (SO2-3), thiosulfate, (S2O23), and polythionates (S3O62-; S4O62-). Because of its wide range of stable oxidation states, from +6to -2, sulfur plays important roles in central biochemistry as a structural and redoxactive element and is intimately related to life on Earth. Unusual reaction pathways involving sulfur compounds become possible by the specific properties of this element. Sulfur occurs in all the major classes of biomolecules, including enzymes, proteins, sugars, nucleic acids, vitamin cofactors, and metabolites. The flexibility of these biomolecules follows from its versatile chemistry. The best known sulfur mineral is perhaps pyrite (Fool's gold), with the chemical formula, FeS2. Sulfur radical anions, such as [S3].-, are responsible for the intense blue color of lapis lazuli, one of the most desired and expensive artists' materials. In the microbial world, inorganic sulfur compounds, e.g., elemental sulfur and sulfate, belong to the most important electron acceptors. Studies on microbial sulfur metabolism revealed many novel enzymes and pathways and advanced the understanding on metabolic processes used for energy conservation, not only of the microbes, but of biology in general. Transition metal sulfur complexes display intriguing catalytic activities, they provide surfaces and complex cavities in metalloenzymes that activate inert molecules such as H2, CO, N2 or N2O, and they catalyze the transformations of numerous organic molecules. Both thiamine diphosphate- (ThDP) and S-adenosyl- L-methionine- (SAM) dependent enzymes belong to Nature's most powerful catalysts with a remarkable spectrum of catalytic activities. In conclusion, given sulfur's diverse properties, evolution made an excellent choice in selecting sulfur as one the basic elements of life.


Assuntos
Enxofre/química , Oxirredução , Sulfatos
19.
Sci Rep ; 10(1): 10941, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32616785

RESUMO

The transition of the martian climate from the wet Noachian era to the dry Hesperian (4.1-3.0 Gya) likely resulted in saline surface waters that were rich in sulfur species. Terrestrial analogue environments that possess a similar chemistry to these proposed waters can be used to develop an understanding of the diversity of microorganisms that could have persisted on Mars under such conditions. Here, we report on the chemistry and microbial community of the highly reducing sediment of Colour Peak springs, a sulfidic and saline spring system located within the Canadian High Arctic. DNA and cDNA 16S rRNA gene profiling demonstrated that the microbial community was dominated by sulfur oxidising bacteria, suggesting that primary production in the sediment was driven by chemolithoautotrophic sulfur oxidation. It is possible that the sulfur oxidising bacteria also supported the persistence of the additional taxa. Gibbs energy values calculated for the brines, based on the chemistry of Gale crater, suggested that the oxidation of reduced sulfur species was an energetically viable metabolism for life on early Mars.


Assuntos
Bactérias/classificação , Bactérias/genética , Biodiversidade , DNA Bacteriano/genética , Sedimentos Geológicos/análise , Marte , Enxofre/química , Bactérias/metabolismo , DNA Ribossômico/genética , Meio Ambiente Extraterreno , Filogenia , RNA Ribossômico 16S , Enxofre/metabolismo
20.
Nucleic Acids Res ; 48(15): 8755-8766, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32621606

RESUMO

The sulfur atom of phosphorothioated DNA (PT-DNA) is coordinated by a surface cavity in the conserved sulfur-binding domain (SBD) of type IV restriction enzymes. However, some SBDs cannot recognize the sulfur atom in some sequence contexts. To illustrate the structural determinants for sequence specificity, we resolved the structure of SBDSpr, from endonuclease SprMcrA, in complex with DNA of GPSGCC, GPSATC and GPSAAC contexts. Structural and computational analyses explained why it binds the above PT-DNAs with an affinity in a decreasing order. The structural analysis of SBDSpr-GPSGCC and SBDSco-GPSGCC, the latter only recognizes DNA of GPSGCC, revealed that a positively charged loop above the sulfur-coordination cavity electrostatically interacts with the neighboring DNA phosphate linkage. The structural analysis indicated that the DNA-protein hydrogen bonding pattern and weak non-bonded interaction played important roles in sequence specificity of SBD protein. Exchanges of the positively-charged amino acid residues with the negatively-charged residues in the loop would enable SBDSco to extend recognization for more PT-DNA sequences, implying that type IV endonucleases can be engineered to recognize PT-DNA in novel target sequences.


Assuntos
Enzimas de Restrição do DNA/genética , Proteínas de Ligação a DNA/genética , DNA/genética , Enxofre/química , Sequência de Aminoácidos/genética , Cristalografia por Raios X , DNA/química , Enzimas de Restrição do DNA/química , Proteínas de Ligação a DNA/química , Escherichia coli/genética , Ligação de Hidrogênio , Ligação Proteica/genética , Domínios Proteicos/genética , Streptomyces/enzimologia
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