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1.
J Hazard Mater ; 421: 126774, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34364214

RESUMO

Waste furniture boards (WFBs) contain hazardous formaldehyde and volatile organic compounds when left unmanaged or improperly disposed through landfilling and open burning. In this study, pyrolysis was examined as a disposal and recovery approach to convert three types of WFBs (i.e., particleboard, plywood, and fiberboard) into value-added chemicals using thermogravimetric analysis coupled with Fourier-transform infrared spectrometry (TG-FTIR) and pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS). TG-FTIR analysis shows that pyrolysis performed at an optimum temperature of 250-550 °C produced volatile products mainly consisting of carbon dioxide, carbon monoxide, and light hydrocarbons, such as methane. Py-GC/MS shows that pyrolysis at different final temperatures and heating rates recovered mainly phenols (25.9-54.7%) for potential use as additives in gasoline, colorants, and food. The calorific value of WFBs ranged from 16 to 18 MJ/kg but the WFBs showed high H/C (1.7-1.8) and O/C (0.8-1.0) ratios that provide low chemical energy during combustion. This result indicates that WFBs are not recommended to be burned directly as fuel, however, they can be pyrolyzed and converted into solid pyrolytic products such as biochar with improved properties for fuel application. Hazardous components, such as cyclopropylmethanol, were removed and converted into value-added compounds, such as 1,4:3,6-dianhydro-d-glucopyranose, for use in pharmaceuticals. These results show that the pyrolysis of WFBs at high temperature and low heating rate is a promising feature to produce value-added chemicals and reduce the formation of harmful chemical species. Thus, the release of hazardous formaldehyde and greenhouse gases into the environment is redirected.


Assuntos
Decoração de Interiores e Mobiliário , Pirólise , Temperatura Alta , Metano , Temperatura
2.
ACS Appl Mater Interfaces ; 13(45): 53955-53964, 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34739211

RESUMO

Tungsten carbide (W2C) has emerged as a potential alternative to noble-metal catalysts toward hydrogen evolution reaction (HER) owing to its Pt-like electronic configuration. However, unsatisfactory activity, dilatory electron transfer, and inefficient synthesizing methods, especially for nanoscale particles, have severely hindered its large-scale applications. Herein, a novel heterostructure composed of W2C and tungsten phosphide (WP) embedded in nitrogen-decorated carbon (W2C/WP@NC) was constructed as an efficient HER electrocatalyst. The as-prepared W2C/WP@NC catalyst exhibits remarkable electrocatalytic activity and robust durability toward HER both in acids and bases. More notably, the W2C/WP@NC catalyst demonstrates low overpotentials of 116.37 and 196.2 mV to afford a current density of 10 mA cm-2 and reveals slight potential decays of about 6.4 and 7.64% over 12 h continuous operation in bases and acids, respectively. The overall water-splitting performance was further evaluated using the W2C/WP@NC catalyst as the cathode and commercial RuO2 as the anode in an electrolyzer, which can realize an overall current density of 10 mA cm-2 and maintain long durability of more than 12 h with a small cell voltage of 1.723 V. This work opens up new opportunities for exploring cost-efficient electrocatalysts in sustainable energy conversion.

3.
Inorg Chem ; 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34757727

RESUMO

Photocatalytic CO2 reduction using solar energy is a promising way to obtain renewable-energy sources for replacing fossil fuels. Through a hydrothermal process, we successfully designed and synthesized three-dimensional (3D) flower-like structured SnS2 with a sheet-like structured quasi-hexagon as the building block. The 3D hierarchical structure is conducive to light capture and absorption, the sheet structure can shorten the transmission path and promote separation of the carriers, and the self-supporting effect can effectively prevent catalyst agglomeration during the catalytic reaction. Therefore, when used in photocatalytic CO2 reduction, SnS2 with a flower-like structure showed excellent photocatalytic performance compared with SnS2 nanoparticles (NPs) under visible-light irradiation with a gas-solid reaction system.

4.
Front Bioeng Biotechnol ; 9: 757906, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34746110

RESUMO

Peripheral nerve injuries have become a common clinical disease with poor prognosis and complicated treatments. The development of tissue engineering pointed a promising direction to produce nerve conduits for nerve regeneration. Electrical and mechanical stimulations have been incorporated with tissue engineering, since such external stimulations could promote nerve cell proliferation, migration and differentiation. However, the combination of electrical and mechanical stimulations (electromechanical stimulation) and its effects on neuron proliferation and axon outgrowth have been rarely investigated. Herein, silver nanowires (AgNWs) embedded polydimethylsiloxane (PDMS) electrodes were developed to study the effects of electromechanical stimulation on rat pheochromocytoma cells (PC12 cells) behaviors. AgNWs/PDMS electrodes demonstrated good biocompatibility and established a stable electric field during mechanical stretching. PC12 cells showed enhanced proliferation rate and axon outgrowth under electrical stimulation alone, and the cell number significantly increased with higher electrical stimulation intensity. The involvement of mechanical stretching in electrical stimulation reduced the cell proliferation rate and axon outgrowth, compared with the case of electrical stimulation alone. Interestingly, the cellular axons outgrowth was found to depend on the stretching direction, where the axons prefer to align perpendicularly to the stretch direction. These results suggested that AgNWs/PDMS electrodes provide an in vitro platform to investigate the effects of electromechanical stimulation on nerve cell behaviors and can be potentially used for nerve regeneration in the future.

5.
Int Heart J ; 62(6): 1199-1206, 2021 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-34744146

RESUMO

Among many diseases, coronary artery disease (CAD) is the primary cause of mortality and morbidity worldwide. With the aim of revealing the underlying genetic characteristics of the CAD subtypes, we recruited patients with CAD and categorized them into subgroups according to the transcriptome expression profiles of the adipose tissue.With the removal of the batch effect, consensus clustering was employed to determine the subgroup numbers. Subgroup-specific genes were determined to conduct analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Weighted gene co-expression network analysis (WGCNA) revealed the subgroup-specific WGCNA modules. Moreover, gene set enrichment analysis (GSEA) was conducted. Overrepresentation enrichment analysis (OEA) of subgroup-specific signatures was also conducted to reveal the significant gene module associated with the corresponding clinical characteristics.After the removal of the batch effect, 77 CAD objects were divided into three subgroups. It was observed that the patients in subgroup III tended to be fat. After analyzing the dominant pathways of each subgroup, we discovered that the protein digestion and absorption pathway was specifically upregulated in subgroup I, which might result from the lowest proportion of the epicardial adipose tissue (EAT) sample. Moreover, subgroup II patients had genetic characteristics of high expression of complement and coagulation cascades and TNF signaling pathway. Furthermore, Th17 cell differentiation was significantly upregulated in subgroup III, indicating that Th17 cell differentiation is related to the clinical characteristics of body mass index (BMI).In conclusion, the genetic classification of CAD subjects indicated that subjects from different subgroups may exhibit specific gene expression patterns, suggesting that more personalized treatment should be applied to patients in each subgroup.

6.
Pestic Biochem Physiol ; 179: 104966, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34802516

RESUMO

Pesticide resistance in spider mites drives the development of acaricides with novel mode of action, which could benefit from RNAi as a screening tool in search of new molecular targets. RNAi via oral delivery of dsRNA has been frequently reported in spider mites, but injection of dsRNA is rarely reported. We compare here the efficiency of oral delivery versus injection of dsRNA in female adult mites. When comparing silencing efficiency, oral delivery of dsRNAs silenced 40.6 ± 8.9% of CPR, 63.8 ± 6.9% of CHMP2A, and 37.7 ± 5.7% of CHMP3 genes. Similar silencing efficiencies were found for injection (48.6 ± 3.7% of CPR, 70.2 ± 4.1% of CHMP2A, 59.8 ± 2.2% of CHMP3), but with much lower quantities of dsRNAs. Oral delivery of dsRNA failed to silence the expression of the CHMP4B gene, but this could be accomplished by injection of dsRNA (23.1 ± 1.0%). When scoring the phenotypic effects of silencing, both oral delivery and injection of CHMP2A- and CHMP3-dsRNA influenced the locomotion speed of mites significantly. For CPR, silencing could only be accomplished by dsRNA injection, not by feeding. CPR silencing significantly impacted the toxicity of a typical acaricide, pyridaben, as the susceptibility of mites raised 2.75-fold. Last, injection of Eya-dsRNA in adults produced transgenerational phenotypic effects on 3.59% of offspring, as quantified by an observed deviation in eye development, while oral delivery of Eya-dsRNA did not. In conclusion, injection of dsRNA is superior to oral delivery in silencing the expression of the selected genes in this study and could be considered the method of choice to study gene function in reverse genetic approaches.


Assuntos
Acaricidas , Ácaros , Tetranychidae , Animais , Ácaros/genética , Interferência de RNA , RNA de Cadeia Dupla/genética
7.
Nat Commun ; 12(1): 6444, 2021 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-34750364

RESUMO

Synaptic pruning during adolescence is important for appropriate neurodevelopment and synaptic plasticity. Aberrant synaptic pruning may underlie a variety of brain disorders such as schizophrenia, autism and anxiety. Dopamine D2 receptor (Drd2) is associated with several neuropsychiatric diseases and is the target of some antipsychotic drugs. Here we generate self-reporting Drd2 heterozygous (SR-Drd2+/-) rats to simultaneously visualize Drd2-positive neurons and downregulate Drd2 expression. Time course studies on the developing anterior cingulate cortex (ACC) from control and SR-Drd2+/- rats reveal important roles of Drd2 in regulating synaptic pruning rather than synapse formation. Drd2 also regulates LTD, a form of synaptic plasticity which includes some similar cellular/biochemical processes as synaptic pruning. We further demonstrate that Drd2 regulates synaptic pruning via cell-autonomous mechanisms involving activation of mTOR signaling. Deficits of Drd2-mediated synaptic pruning in the ACC during adolescence lead to hyper-glutamatergic function and anxiety-like behaviors in adulthood. Taken together, our results demonstrate important roles of Drd2 in cortical synaptic pruning.

9.
J Alzheimers Dis ; 2021 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-34776438

RESUMO

BACKGROUND: Chinese Herbal Medicines (CHMs), as an important and integral part of a larger system of medicine practiced in China, called Traditional Chinese Medicine (TCM), have been used in stroke therapy for centuries. A large body of studies suggest that some Chinese herbs can help reverse cognitive impairment in stroke patients, while whether these herbs also exert therapeutic benefits for Alzheimer's disease remains to be seen. OBJECTIVE: To address this issue, we selected four types of CHMs that are commonly prescribed for stroke treatment in clinical practice, namely DengZhanXiXin (D1), TongLuoJiuNao (T2), QingKaiLing (Q3), and HuangQinGan (H4), and tested their effects on amyloid-ß protein precursor (AßPP) processing in vitro. METHODS: AßPP, ß-secretase (BACE1), and 99-amino acid C-terminal fragment of AßPP (C99) stably transfected cells were used for the tests of AßPP processing. The production of Aß, activity of BACE1, neprilysin (NEP), and γ-secretase were assessed by ELISA, RT-PCR, and western blot. RESULTS: By upregulating BACE1 activity, D1 increased Aß production whereas decreased the ratio of Aß 42/Aß 40; by downregulating BACE1 activity and modulating the expression of γ-secretase, T2 decreased Aß production and the ratio of Aß 42/Aß 40; by downregulating BACE1 activity, Q3 decreased Aß production; H4 did not change Aß production due to the simultaneously downregulation of BACE1 and NEP activity. CONCLUSION: Our study indicates that these four anti-stroke CHMs regulate AßPP processing through different mechanisms. Particularly, T2 with relatively simple components and prominent effect on AßPP processing may be a promising candidate for the treatment of AD.

11.
Support Care Cancer ; 2021 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-34845502

RESUMO

PURPOSE: Abiraterone acetate, prescribed for metastatic prostate cancer, has enhanced absorption with food. This effect was exploited in a randomized trial which showed noninferiority of PSA decline for 250 mg abiraterone with a low-fat meal (LOW) compared to 1,000 mg abiraterone fasting (STD). Drug was obtained via patient insurance. Patient out-of-pocket costs and adherence were surveyed. METHODS: Trial participants were randomized to STD or LOW, and surveys of adherence and out-of-pocket costs were administered at baseline and just before coming off study (follow-up). RESULTS: Out-of-pocket costs were available from 20 of 36 STD and 21 of 36 LOW patients. Median out-of-pocket costs for a month of drug were $0 (LOW) and $5 (STD); mean costs were $43.61 (LOW) and $393.83 (STD). The two groups did not differ significantly (p = 0.421). Maximum out-of-pocket cost was $1,000 (LOW) and $4,000 (STD). Monthly out-of-pocket costs > $500 were found in 1 LOW and 5 STD patients. For adherence, only 11 STD and 19 LOW patients had questionnaires completed at both baseline and follow-up. STD adherence was 98.18% at baseline and 91.69% at follow-up, differing significantly (p = 0.0078). LOW adherence was 96.52% at baseline and 97.86% at follow-up, not differing significantly (p = 0.3511). Adherence did not correlate with demographics. At follow-up, increasing adherence correlated significantly with decreasing dose (p = 0.013; rho = - 0.458). CONCLUSIONS: Out-of-pocket costs did not differ significantly in this limited analysis. Adherence was significantly different in STD as the trial progressed, which was not found in LOW. TRIAL REGISTRATION: ClinicalTrials.gov NCT01543776; registered March 5, 2012.

12.
Membranes (Basel) ; 11(11)2021 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-34832047

RESUMO

Biogenic microvesicles (MVs) play a pivotal role in intercellular signal communication, thus initiating critical biological responses such as the proliferation of cancer cells, gene and protein transport, and chemo-drug resistance. In addition, they have been recognized as having great potential in drug delivery applications. However, the productivity of biologically produced MVs is not sufficient for clinical applications. In this study, synthetic poly(lactic-co-glycolic acid) (PLGA) MVs were prepared via a double emulsion method. The PLGA MVs had a biogenic MV-mimic vesicular structure with a hydrophilic core/surface and hydrophobic interior of the shell, showing great potential for drug delivery. We successfully embedded hydrophobic iron carbonyl (IC), a carbon monoxide (CO) donor, in the PLGA shell region, enabling the delivery of IC in an aqueous solution. Because of the intrinsic properties of PLGA, it was susceptible to temperature, and the MVs could easily collapse in a warm environment, leading to the decomposition of IC into CO. The in vitro result indicated that the cell viability of A549 lung carcinoma cells significantly decreased to 14% after treatment with IC-loaded PLGA MVs for 24 h, suggesting that these synthetic PLGA MVs constitute an excellent drug delivery platform.

13.
BMC Geriatr ; 21(1): 614, 2021 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-34717574

RESUMO

BACKGROUND: Falls are a major health burden for older adults with Parkinson's disease (PD), but there is currently no reliable questionnaire to capture the circumstances and consequences of falls in older adults with PD. This study aimed to develop a PD-specific falls questionnaire and to evaluate its test-retest reliability in older adults with PD. METHODS: A novel PD-specific falls questionnaire (PDF-Q) was developed in two modes (online and paper-based version) and used to assess falls and near-falls events over the past 12-months. Questions were agreed upon by an expert group, with the domains based on previous falls-related questionnaires. The questions included the number and circumstances (activities, location and direction) of falls and near-falls, and consequences (injuries and medical treatment) of falls. The PDF-Q was distributed to 46 older adults with PD (online n = 30, paper n = 16), who completed the questionnaire twice, 4 weeks apart. Kappa (κ) statistics were used to establish test-retest reliability of the questionnaire items. RESULTS: Pooled results from both questionnaires for all participants were used to assess the overall test-retest reliability of the questionnaire. Questions assessing the number of falls (κ = 0.41) and the number of near-falls (κ = 0.51) in the previous 12-months demonstrated weak agreement, while questions on the location of falls (κ = 0.89) and near-falls (κ = 1.0) demonstrated strong to almost perfect agreement. Questions on the number of indoor (κ = 0.86) and outdoor (κ = 0.75) falls demonstrated moderate to strong agreement, though questions related to the number of indoor (κ = 0.47) and outdoor (κ = 0.56) near-falls demonstrated weak agreement. Moderate to strong agreement scores were observed for the most recent fall and near-fall in terms of the direction (indoor fall κ = 0.80; outdoor fall κ = 0.81; near-fall κ = 0.54), activity (indoor fall κ = 0.70; outdoor fall κ = 0.82; near-fall κ = 0.65) and cause (indoor fall κ = 0.75; outdoor fall κ = 0.62; near-fall κ = 0.56). CONCLUSIONS: The new PDF-Q developed in this study was found to be reliable for capturing the circumstances and consequences of recent falls and near-falls in older adults with PD.


Assuntos
Doença de Parkinson , Idoso , Humanos , Doença de Parkinson/diagnóstico , Doença de Parkinson/epidemiologia , Reprodutibilidade dos Testes , Inquéritos e Questionários
14.
Hepatology ; 2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34633706

RESUMO

BACKGROUND AND AIMS: Hispanics are disproportionately affected by non-alcoholic fatty liver disease, liver fibrosis, cirrhosis, and hepatocellular carcinoma. Preventive strategies and non-invasive means to identify those in this population at high risk for liver fibrosis, are urgently needed. We aimed to characterize the gut microbiome signatures and related biological functions associated with liver fibrosis in Hispanics and identify environmental and genetic factors affecting them. APPROACH AND RESULTS: Subjects of the population-based Cameron County Hispanic Cohort (n=217) were screened by vibration-controlled transient elastography (FibroScan). Among them, 144 (66.7%) had steatosis and 28 (13.0%) had liver fibrosis. The gut microbiome of subjects with liver fibrosis was enriched with immunogenic commensals (e.g. Prevotella copri, Holdemanella, Clostridiaceae 1) and depleted of Bacteroides caccae, Parabacteroides distasonis, Enterobacter and Marinifilaceae. The liver fibrosis-associated metagenome was characterized by changes in the urea cycle, L-citrulline biosynthesis and creatinine degradation pathways, and altered synthesis of B vitamins and lipoic acid. These metagenomic changes strongly correlated with the depletion of Parabacteroides distasonis and enrichment of Prevotella and Holdemanella. Liver fibrosis was also associated with depletion of bacterial pathways related to L-fucose biosynthesis. Alcohol consumption, even moderate, was associated with high Prevotella abundance. The single nucleotide polymorphisms rs3769502 and rs7573751 in the NCK2 gene positively associated with high Prevotella abundance. CONCLUSION: Hispanics with liver fibrosis display microbiome profiles and associated functional changes that may promote oxidative stress and a pro-inflammatory environment. These microbiome signatures, together with NCK2 polymorphisms, may have utility in risk modeling and disease prevention in this high-risk population.

15.
J Mater Chem B ; 9(41): 8686-8693, 2021 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-34617098

RESUMO

Short peptides with self-assembled nanostructures are widely applied in the areas of drug delivery systems and biomaterials. In this article, we create a new peptide-based hydrogelator (Fmoc-FFRRVR) based on N-fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF) through an approach to improve its hydrophilicity. Compared to Fmoc-FF, Fmoc-FFRRVR prefers to form a hydrogel under mild conditions, and the gelation time is only 2 s. Fmoc-FFRRVR self-assembles into organized arrays of ß-sheets in nanofibers via π-stacking of Fmoc-FF, which are supported by circular dichroism and fluorescence emission spectroscopy. Rheology results confirm that the hydrogel of Fmoc-FFRRVR is elastic, reversible and injectable. The newly discovered hydrogel not only retains some excellent performances of Fmoc-FF, but also can be used as a drug carrier for biomedical applications.

16.
Ying Yong Sheng Tai Xue Bao ; 32(8): 2818-2828, 2021 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-34664455

RESUMO

Taking the main production area of yam in North China Plain as the research area, we analyzed the status of soil fertility and fertilizer application in yam production through field investigation and tracking monitoring, examined soil nutrient balance using the input-output model of nutrients in agricultural system, and assessed the environmental risks in the yam planting system. The results showed that: 1) the contents of soil organic matter and total N were extremely low, and the contents of available P and available Zn were both low; both nitrate and available Cu contents were at the middle level, the contents of soil slowly available K, available S, and exchangeable Ca and Mg were all extremely high, the contents of available K, available Fe, and available Mn were all at high level; 2) The nitrogen (N), phosphorus (P2O5), and potassium (K2O) inputs were 575-943 kg·hm-2, 341-981 kg·hm-2, and 655-1219 kg·hm-2 during the whole growth period of yam, with chemical fertilizer accounting for 83.0%, 88.6%, and 91.3%, respectively; The input imbalance between organic and inorganic fertilizer, as well as the excessive nutrients input were prominent; 3) The surplus rate of soil nitrogen, phosphorus and potassium reached 271.14 kg·hm-2, 466.34 kg·hm-2, and 739.97 kg·hm-2, with corresponding surplus ratio of 48.7%, 258.1%, and 324.5%, respectively, which all exceeded the environmental safety threshold and were classified as moderate risk, severe risk, and severe risk, respectively. The overall environmental risk caused by chemical fertilizer application in yam production had reached severe risk level.


Assuntos
Dioscorea , Solo , China , Nutrientes , Medição de Risco
17.
Clin Transl Sci ; 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34670024

RESUMO

Combination therapy with platelet inhibitors and acid-suppressive agents is recommended for patients with acute ST-segment elevation myocardial infarction (STEMI) who underwent percutaneous coronary intervention (PCI), but there remains a paucity of data to evaluate both the efficacy and safety of these combinations. In this prospective study, a total of 170 patients with acute STEMI who underwent PCI were divided into four groups: pantoprazole + ticagrelor, omeprazole + ticagrelor, ranitidine + ticagrelor, and ticagrelor only. The risk of PCI, antithrombotic efficacy, cardiac function, and main end points were evaluated and compared. No significant differences were found in infarction-related artery perfusion indexes (thrombolysis in myocardial infarction [TIMI], corrected TIMI frame count), the incidence of stent thrombosis after PCI, platelet indicators (platelet count, mean platelet volume, and platelet distribution width), platelet activation (P-selectin and glycoprotein IIb/IIIa levels), platelet aggregation (thrombelastography indicators, such as ADP% and MAADP ), myocardial necrosis biomarker (creatine kinase isoenzyme-MB and cardiac troponin I) levels, brain natriuretic peptide levels, the incidence of ischemic end point events, and the incidence of other tissue and organ bleeding events among the four groups. The incidence of gastrointestinal (GI) bleeding events in the proton pump-inhibitor (PPI) group was significantly lower than that in the control group, whereas in the H2 receptor antagonist (H2RA) group it was not significantly different from the control group. The short-term combination therapy with ticagrelor and PPIs or H2RA is safe and effective in patients with acute STEMI after PCI. In addition, the PPIs combined with ticagrelor could reduce the incidence of GI bleeding events without increasing the incidence of ischemic events.

20.
Front Microbiol ; 12: 735793, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34630359

RESUMO

Dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) are widespread in marine environment, and are important participants in the global sulfur cycle. Microbiol oxidation of DMS to DMSO represents a major sink of DMS in marine surface waters. The SAR11 clade and the marine Roseobacter clade (MRC) are the most abundant heterotrophic bacteria in the ocean surface seawater. It has been reported that trimethylamine monooxygenase (Tmm, EC 1.14.13.148) from both MRC and SAR11 bacteria likely oxidizes DMS to generate DMSO. However, the structural basis of DMS oxidation has not been explained. Here, we characterized a Tmm homolog from the SAR11 bacterium Pelagibacter sp. HTCC7211 (Tmm7211). Tmm7211 exhibits DMS oxidation activity in vitro. We further solved the crystal structures of Tmm7211 and Tmm7211 soaked with DMS, and proposed the catalytic mechanism of Tmm7211, which comprises a reductive half-reaction and an oxidative half-reaction. FAD and NADPH molecules are essential for the catalysis of Tmm7211. In the reductive half-reaction, FAD is reduced by NADPH. In the oxidative half-reaction, the reduced FAD reacts with O2 to form the C4a-(hydro)peroxyflavin. The binding of DMS may repel the nicotinamide ring of NADP+, and make NADP+ generate a conformational change, shutting off the substrate entrance and exposing the active C4a-(hydro)peroxyflavin to DMS to complete the oxidation of DMS. The proposed catalytic mechanism of Tmm7211 may be widely adopted by MRC and SAR11 bacteria. This study provides important insight into the conversion of DMS into DMSO in marine bacteria, leading to a better understanding of the global sulfur cycle.

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