RESUMO
Past and present habitability of Mars have been intensely studied in the context of the search for signals of life. Despite the harsh conditions observed today on the planet, some ancient Mars environments could have harbored specific characteristics able to mitigate several challenges for the development of microbial life. In such environments, Fe2+ minerals like siderite (already identified on Mars), and vivianite (proposed, but not confirmed) could sustain a chemolithoautotrophic community. In this study, we investigate the ability of the acidophilic iron-oxidizing chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans to use these minerals as its sole energy source. A. ferrooxidans was grown in media containing siderite or vivianite under different conditions and compared to abiotic controls. Our experiments demonstrated that this microorganism was able to grow, obtaining its energy from the oxidation of Fe2+ that came from the solubilization of these minerals under low pH. Additionally, in sealed flasks without CO2, A. ferrooxidans was able to fix carbon directly from the carbonate ion released from siderite for biomass production, indicating that it could be able to colonize subsurface environments with little or no contact with an atmosphere. These previously unexplored abilities broaden our knowledge on the variety of minerals able to sustain life. In the context of astrobiology, this expands the list of geomicrobiological processes that should be taken into account when considering the habitability of environments beyond Earth, and opens for investigation the possible biological traces left on these substrates as biosignatures.
Assuntos
Acidithiobacillus , Marte , Acidithiobacillus/metabolismo , Acidithiobacillus/crescimento & desenvolvimento , Oxirredução , Ferro/metabolismo , Concentração de Íons de Hidrogênio , Compostos Ferrosos/metabolismo , Minerais/metabolismo , Exobiologia , Meio Ambiente Extraterreno , Carbonatos , Compostos FérricosRESUMO
Iron [Fe(II)] and copper [Cu(II)] overloads in rat brain are associated with oxidative stress and damage. The purpose of this research is to study whether brain antioxidant enzymes are involved in the control of intracellular redox homeostasis in the brain of rats male Sprague-Dawley rats (80-90 g) that received drinking water supplemented with either 1.0 g/L of ferrous chloride (n = 24) or 0.5 g/L cupric sulfate (n = 24) for 42 days. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and glutathione transferase (GT) activities in brain were determined by spectrophotometric methods and NO production by the content of nitrite concentration in the organ. Chronic treatment with Fe(II) and Cu(II) led to a significant decrease of nitrite content and SOD activity in brain. Activity of NADPH oxidase increased with Cu(II) treatment. Concerning Fe(II), catalase and GT activities increased in brain after 28 and 4 days of treatment, respectively. In the case of Cu(II), catalase activity decreased whereas GT activity increased after 2 and 14 days, respectively. The regulation of redox homeostasis in brain involves changes of the activity of these enzymes to control the steady state of oxidant species related to redox signaling pathways upon Cu and Fe overload. NO may serve to detoxify cells from superoxide anion and hydrogen peroxide with the concomitant formation of peroxynitrite. However, the latest is a powerful oxidant which leads to oxidative modifications of biomolecules. These results suggest a common pathway to oxidative stress and damage in brain for Cu(II) and Fe(II).
Assuntos
Antioxidantes , Água Potável , Animais , Antioxidantes/química , Encéfalo/metabolismo , Catalase/metabolismo , Cobre/metabolismo , Sulfato de Cobre , Compostos Ferrosos/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Transferase/metabolismo , Peróxido de Hidrogênio/metabolismo , Ferro/metabolismo , Masculino , NADP/metabolismo , NADPH Oxidases/metabolismo , Nitritos , Oxidantes/metabolismo , Ácido Peroxinitroso/metabolismo , Ratos , Ratos Sprague-Dawley , Superóxido Dismutase , Superóxidos/metabolismoRESUMO
Expanding the reaction scope of natural metalloenzymes can provide new opportunities for biocatalysis. Mononuclear non-heme iron-dependent enzymes represent a large class of biological catalysts involved in the biosynthesis of natural products and catabolism of xenobiotics, among other processes. Here, we report that several members of this enzyme family, including Rieske dioxygenases as well as α-ketoglutarate-dependent dioxygenases and halogenases, are able to catalyze the intramolecular C-H amination of a sulfonyl azide substrate, thereby exhibiting a promiscuous nitrene transfer reactivity. One of these enzymes, naphthalene dioxygenase (NDO), was further engineered resulting in several active site variants that function as C-H aminases. Furthermore, this enzyme could be applied to execute this non-native transformation on a gram scale in a bioreactor, thus demonstrating its potential for synthetic applications. These studies highlight the functional versatility of non-heme iron-dependent enzymes and pave the way to their further investigation and development as promising biocatalysts for non-native metal-catalyzed transformations.
Assuntos
Dioxigenases/metabolismo , Compostos Ferrosos/metabolismo , Iminas/metabolismo , Metaloproteínas/metabolismo , Aminação , Biocatálise , Dioxigenases/química , Dioxigenases/isolamento & purificação , Escherichia coli/química , Escherichia coli/citologia , Escherichia coli/metabolismo , Compostos Ferrosos/química , Compostos Ferrosos/isolamento & purificação , Iminas/química , Metaloproteínas/química , Metaloproteínas/isolamento & purificação , Modelos Moleculares , Estrutura MolecularRESUMO
This study aimed to evaluate the quality of the royal jelly produced by Apis mellifera bees in the presence of different iron concentrations (ferrous sulfate heptahydrate-0, 25, 50, and 100 mg L-1). Two-dimensional electrophoresis was used for the fractionation of royal jelly proteins, and iron level was quantified using flame atomic absorption spectrometry technique. The proteins were identified using electrospray ionisation mass spectrometry. Analysis of variance followed by the Tukey test (P < 0.05) was utilised. Dietary supplementation with mineral Fe affected the protein content and number of proteins in the experimental period. Further, the diet containing the highest iron concentration showed a greater number of spots containing iron, as well as in the abdomen of the bees. The most protein containing Fe were classified as major royal jelly proteins. These results showed that Fe influenced the quality of royal jelly and can improve its nutritional value.
Assuntos
Ácidos Graxos/química , Compostos Ferrosos/análise , Proteínas de Insetos/análise , Animais , Abelhas , Suplementos Nutricionais , Ácidos Graxos/biossíntese , Compostos Ferrosos/administração & dosagem , Compostos Ferrosos/metabolismo , Proteínas de Insetos/metabolismoRESUMO
Aiming to reduce feed costs, cottonseed oil (CSO) has been used as an alternative component in diets for broilers. However, this oil contains gossypol, an antinutritional agent that impacts the use of mineral elements, inhibits glucose uptake, and has a direct inhibitory action on intestinal enzymes. Nevertheless, toxic effects of gossypol can be prevented by the addition of iron salts, such as ferrous sulfate (FS), to the diet. This work was conducted to evaluate performance and gene expression of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the intestines of 21- and 42-day-old broilers fed 0, 2, 4, or 6% concentrations of CSO, with or without FS. All CSO diets led to weight gain (WG) at 21 D. At 42 D, an increase in WG and a decrease in feed conversion (FCR) in the diets containing FS were observed. In 21-day-old birds supplemented with 4% CSO and FS, an increase in GPx gene expression was observed when compared to the 6% level. Animals (42 day old) supplemented with 6% CSO and FS presented greater expression of SOD gene when compared to 2% CSO and FS. In addition, a higher GPx expression in broilers supplemented with 6% CSO and FS compared to 6% CSO without FS was achieved. In conclusion, including CSO in the diets of broiler favors WG in animals at 21 D of age, independent of the presence or absence of FS; and including 4% CSO and FS in the diet of these animals alters the expression of the GPx gene in the intestine, so it is not necessary to add FS at 21 D. On the other hand, in 42-day-old broilers, the addition of FS is indicated, due to increases WG, decreased FCR and at the 6% CSO level without FS increase in the expression of the SOD and GPx genes.
Assuntos
Antioxidantes/metabolismo , Galinhas/fisiologia , Óleo de Sementes de Algodão/metabolismo , Compostos Ferrosos/metabolismo , Aumento de Peso/efeitos dos fármacos , Ração Animal/análise , Animais , Catalase/metabolismo , Óleo de Sementes de Algodão/administração & dosagem , Dieta/veterinária , Suplementos Nutricionais/análise , Relação Dose-Resposta a Droga , Compostos Ferrosos/administração & dosagem , Expressão Gênica/efeitos dos fármacos , Glutationa Peroxidase/metabolismo , Intestinos/efeitos dos fármacos , Intestinos/fisiologia , Masculino , Distribuição Aleatória , Superóxido Dismutase/metabolismoRESUMO
Previously, ferrocene incorporation into the principal structural component of biologically active molecules resulted in enhanced cytotoxic activity against hormone-dependent MCF-7 and T-47D and hormone-independent MDA-MB-231 breast-cancer cell lines. Here we explore 4 new ferrocene estrogen conjugates at position 16 of the estrogen hormone and compared them to the previously reported ferrocene estrogen conjugate 3-ferrocenyl-estra-1,3,5(10)-triene-17ß-ol. The ferrocene conjugate 16-ferrocenylidene-3-hydroxyestra-1,3,5(10)-trien-17-one was synthesized using estrone and ferrocene carboxaldehyde as starting materials in 86% yield. This ferrocene complex was used as the starting material for the synthesis of new ferrocene estrogen conjugates by a short linker group at position 16 of the estrogen hormone. The position and stereochemistry of the linker was verified by its crystal structure. The ferrocene redox behavior, in vitro studies on breast-cancer cell lines and docking studies on ERα are presented. The data suggest that the ferrocene conjugates presented, either at position 3 or 16 of the estrogen, could serve as vectors and can be recognized by ERα as a delivery mechanism into the cell. These new ferrocene hormone conjugates showed cytotoxic activity comparable to that of conventional therapeutic drugs such as tamoxifen and cisplatin.
Assuntos
Antineoplásicos/síntese química , Neoplasias da Mama/tratamento farmacológico , Estrogênios/química , Compostos Ferrosos/síntese química , Metalocenos/síntese química , Aminoácidos/química , Antineoplásicos/metabolismo , Transporte Biológico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Desenho de Fármacos , Receptor alfa de Estrogênio/efeitos dos fármacos , Estrogênios/metabolismo , Feminino , Compostos Ferrosos/metabolismo , Humanos , Metalocenos/metabolismo , Simulação de Acoplamento Molecular/métodos , Estrutura Molecular , Ligação Proteica , Relação Estrutura-AtividadeRESUMO
The optimization of ligninolytic enzyme (LE) activities in a novel fungal co-culture between Pycnoporus sanguineus and Beauveria brongniartii were studied using a Plackett-Burman experimental design (PBED) and a central composite design (CCD). In addition, H2O2 role was analyzed. Laccase (EC. 1.10.3.2) and MnP (EC 1.11.1.14) activities of P. sanguineus increased 6.0- and 2.3-fold, respectively, in the co-culture with B. brongniartii. The H2O2 content was higher in the co-culture (0.33-7.12-fold) than in the P. sanguineus monoculture. The PBED revealed that yeast extract (YE), FeSO4, and inoculum amount were significant factors for laccase and MnP activities and H2O2 production in the co-culture, which increased by 8.2-, 5.2- and 1.03-fold, respectively. The YE and FeSO4 were studied using a CCD to optimize the studied response variables. Laccase activity was enhanced 1.5-fold by CCD, the optimal amount of YE was 0.366 g L-1. Quadratic term of FeSO4 modulated MnP activity and was associated with a 4.28-fold increase compared to the PBED. Both YE and its quadratic term significantly affected H2O2 production; however, the CCD did not enable an increase in H2O2 production. Pearson correlation indicated an increase in laccase (r2=0.4411, p = 0.0436) and MnP (r2=0.5186, p = 0.0198) activities following increases in H2O2 in the co-culture system.
Assuntos
Técnicas de Cocultura/métodos , Proteínas Fúngicas/metabolismo , Lacase/metabolismo , Peroxirredoxinas/metabolismo , Análise de Variância , Beauveria/enzimologia , Beauveria/crescimento & desenvolvimento , Técnicas de Cocultura/instrumentação , Meios de Cultura/metabolismo , Compostos Ferrosos/metabolismo , Peróxido de Hidrogênio/metabolismo , Pycnoporus/enzimologia , Pycnoporus/crescimento & desenvolvimentoRESUMO
The mangrove crab Ucides cordatus is a bioindicator of aquatic contamination. In this work, the iron availability and redox activity of saccharide-coated mineral iron supplements (for both human and veterinary use) and ferrocene derivatives in Saline Ucides Buffer (SUB) medium were assessed. The transport of these metallodrugs by four different hepatopancreatic cell types (embryonic (E), resorptive (R), fibrillar (F), and blister (B)) of U. cordatus were measured. Organic coated iron minerals (iron supplements) were stable against strong chelators (calcein and transferrin). Ascorbic acid efficiently mediated the release of iron only from ferrocene compounds, leading to redox-active species. Ferrous iron and iron supplements were efficient in loading iron to all hepatopancreatic cell types. In contrast, ferrocene derivatives were loaded only in F and B cell types. Acute exposition to the iron compounds resulted in cell viability of 70-95%, and to intracellular iron levels as high as 0.40 µmol L-1 depending upon the compound and the cell line. The easiness that iron from iron metallodrugs was loaded/transported into U. cordatus hepatopancreatic cells reinforces a cautionary approach to the widespread disposal and use of highly bioavailable iron species as far as the long-term environmental welfare is concerned.
Assuntos
Braquiúros/metabolismo , Compostos Ferrosos/metabolismo , Hepatopâncreas/citologia , Ferro/metabolismo , Metalocenos/metabolismo , Poluentes Químicos da Água/análise , Animais , Braquiúros/química , Braquiúros/efeitos dos fármacos , Braquiúros/fisiologia , Compostos Ferrosos/análise , Compostos Ferrosos/química , Hepatopâncreas/efeitos dos fármacos , Humanos , Ferro/análise , Metalocenos/análise , Metalocenos/químicaRESUMO
The Fenton-like reductive cleavage of antimalarial peroxides like artemisinin by iron(II) species is a chemical reaction whose mechanistic pathway has not been yet fully understood; it is, however, known that there is considerable production of radical species centered at both the oxygen and carbon, which are important to the therapeutical effects of those compounds. This article reports kinetic data for the reaction of artemisinin and two model 1,2,4-trioxolanes with iron(II) species and also a mechanistic interpretation of this reductive cleavage from transition state thermodynamics. The suggestion of the presence of an enhancing specific factor inside the plasmodium is made.
Assuntos
Antimaláricos/química , Artemisininas/química , Compostos Ferrosos/química , Compostos Heterocíclicos/química , Antimaláricos/metabolismo , Artemisininas/metabolismo , Carbono/química , Desenho de Fármacos , Compostos Ferrosos/metabolismo , Radicais Livres/química , Compostos Heterocíclicos/metabolismo , Cinética , Oxirredução , Oxigênio/química , TermodinâmicaRESUMO
Friendly environmental hydrometallurgy at low temperatures is principally promoted by Acidithiobacillus ferrivorans. Until recently, the synergy between cold tolerance and the molecular mechanism of ferrous iron (Fe2+) oxidation was unknown. In the present paper, we conducted a physiological and comparative genomics analysis of the new strain A. ferrivorans PQ33 to elucidate the oxidation mechanism at low temperatures, with emphasis placed on trehalose and the Rus operon. PQ33 exhibited a doubling time of 66.6 h in Fe2+ at pH 1.6 and 63.6 h in CuS at 5 °C. Genomic island (GI) identification and comparative genome analysis were performed with four available genomes of Acidithiobacillus sp. The genome comprised 3,298,172 bp and 56.55% GC content. In contrast to ATCC Acidithiobacillus ferrooxidans strains, the genome of A. ferrivorans PQ33 harbors one GI, which contains a RusB gene. Moreover, five genes of peptidyl-prolyl cis-trans isomerase (PPIases) were observed. Furthermore, comparative analysis of the trehalose operon suggested the presence of a horizontal transfer event. In addition, comparison of rusticyanin proteins revealed that RusB has better intrinsic flexibility than RusA. This comparison suggests psychrotolerant fitness and supports the genetic canalization of A. ferrivorans PQ33 for oxidation at low temperature.