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1.
J Affect Disord ; 365: 230-236, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39147155

RESUMO

BACKGROUND: Transgender women have a high prevalence of suicidal ideation, with stress and low interpersonal needs as its main risk factors. This study aimed to investigate the mediating role of interpersonal needs on the relationship between perceived stress and suicidal ideation among transgender women in China. METHODS: A cross-sectional study was conducted in Shenyang and Kunming from April to September 2018. 247 transgender women were recruited. Sociodemographic statistics, perceived stress, interpersonal needs and suicidal ideation were obtained. Correlation analysis and mediation analysis were performed to test the relationship among perceived stress, suicidal ideation and interpersonal needs. RESULTS: 14.6 % of the participants reported suicidal ideation within a year. Perceived stress was positively correlated with suicidal ideation (r = 0.228, p < 0.001), interpersonal needs and its three dimensions (r = 0.300-0.583, ps < 0.001)-thwarted belongingness, perceived burdensomeness and social exclusion. Interpersonal needs and its three dimensions were also positively correlated with suicidal ideation (r = 0.148-0.299, ps < 0.05). Interpersonal needs, perceived burdensomeness and social exclusion partly mediated the relationship between perceived stress and suicidal ideation, while thwarted belongingness didn't play a mediating role. LIMITATIONS: Cross-sectional study limited confirmation of causality between variables. The investigation didn't aim at the specific stressors of sexual minorities. And that participants came from only two regions might affect the generalization of the results. CONCLUSIONS: We found a partial mediating role of interpersonal needs between stress and suicidal ideation. Stress reduction and increased social inclusion are needed to reduce suicidal ideation in transgender women.

2.
Chemosphere ; 363: 142831, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38996983

RESUMO

The common polyvinylidene fluoride (PVDF) membrane itself is susceptible to membrane fouling, especially biofouling, which is a serious threat. In this study, PVDF membrane was modified with ciprofloxacin (CIP) through co-blending to investigate the filtration properties, bacterial inhibition and fouling resistance. Modified membranes were prepared by adding 0.3 g (MC0.3), 0.6 g (MC0.6), 0.9 g (MC0.9) and 1.2 g (MC1.2) CIP per 100 g casting solution. Among these modified membranes, MC0.6 showed the best filtration performances, with the pure water flux stabilized at about 416.67 L/(m2·h) and bovine serum albumin (BSA) rejection of 92.0% at a trans-membrane pressure of 0.1 MPa. The pore size was reduced, the average roughness was reduced to 29.4 nm, the contact angle was lowered to 68.9°, and the hydrophilicity was greatly improved. The width of the inhibition circle produced by MC0.6 was 0.35-0.45 mm, and the modified membrane showed good inhibition of non-specific bacteria and algal removal during urban river water filtration. The rejection of BSA was increased by 16.32% compared to the base membrane and the adsorption rate for BSA was reduced by 68.45%. In addition, the removal of conventional pollutants in urban river water by the modified membranes for was also improved. Compared with that of the base membrane, the removal of TN, NH3-N, TP and COD by MC0.6 was increased by 10.58%, 12.45%, 15.44% and 13.53%. The results showed that CIP co-blending modified PVDF membrane could effectively improve membrane performances and has good value for water treatment.


Assuntos
Antibacterianos , Incrustação Biológica , Ciprofloxacina , Filtração , Membranas Artificiais , Polivinil , Purificação da Água , Polivinil/química , Ciprofloxacina/química , Ciprofloxacina/farmacologia , Filtração/métodos , Purificação da Água/métodos , Incrustação Biológica/prevenção & controle , Antibacterianos/química , Antibacterianos/farmacologia , Soroalbumina Bovina/química , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Polímeros de Fluorcarboneto
3.
Nutrients ; 16(11)2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38892538

RESUMO

Diet is one of the most important ways to intervene and promote the health of older adults and reduce all-cause mortality. This study aimed to investigate the association between dietary patterns and all-cause mortality in the Chinese old. This study involved 11,958 subjects aged 65-116 years in the Chinese Longitudinal Healthy Longevity Survey (CLHLS) from 2008 to 2018. Dietary patterns were derived from principal component analysis (PCA) with varimax rotation. Four dietary patterns were derived: the 'milk-egg-sugar pattern', 'carnivorous pattern', 'healthy pattern', and 'northeastern pattern'. Cox proportional hazard models were built for males and females separately to estimate the relationship between different dietary patterns and all-cause mortality. After adjusting for all covariates, the milk-egg-sugar pattern played a reverse role in mortality risk in males and females in different quartiles. In the carnivorous pattern, only males in the fourth quartile were observed to have a significantly reduced mortality risk (HR = 0.84 (95% CI: 0.77-0.93)). Both genders benefited from the healthy pattern, which consistently lowered mortality risk across all quartiles (males: HR = 0.87 (95% CI: 0.84-0.89); females: HR = 0.95 (95% CI: 0.92-0.97)). The northeastern pattern also showed an inverse association with all-cause mortality in males (HR = 0.94 (95% CI: 0.92-0.97)) and females (HR = 0.96 (95% CI: 0.93-0.98)). This study showed the association between dietary patterns and all-cause mortality in the Chinese old, which is significant for further quantitative studies.


Assuntos
Dieta , Longevidade , Humanos , Masculino , Feminino , Idoso , Estudos Longitudinais , China/epidemiologia , Idoso de 80 Anos ou mais , Dieta/estatística & dados numéricos , Mortalidade , Modelos de Riscos Proporcionais , Comportamento Alimentar , Causas de Morte , Padrões Dietéticos , População do Leste Asiático
4.
J Affect Disord ; 360: 42-49, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-38815759

RESUMO

BACKGROUND: HIV-positive men who have sex with men (MSM) are at high risk of suicide and experience intersectional inequalities. The Social Determinants of Health (SDH) framework provides valuable insights into how inequalities can lead to adverse outcomes. This study aimed to employ the SDH framework to identify factors that contribute to suicidal behaviors among this population. METHODS: 1410 HIV-positive MSM were recruited using a web-based questionnaire, whose mean age was 30.77 ± 6.92 years old. Participants completed questionnaires including baseline information and psychological measurements, such as Suicidal Behaviors Questionnaire-Revised (SBQ-R). Logistic regression analysis was conducted to screen for risk factors associated with suicidal behaviors. RESULTS: More than half of the participants (53.3 %, 752/1410) had an SBQ score of 7 or higher. Binary logistic regression analysis of structural and intermediary determinants (Model 3) revealed that sexual orientation, stigma (ORs: 1.018, 95 % CI: 1.005-1.032), interpersonal needs (ORs: 1.021, 95 % CI: 1.010-1.031), depression (ORs: 1.037, 95 % CI: 1.001-1.074) and entrapment (ORs: 1.018, 95 % CI: 1.004-1.032) were positively correlated with suicidal behaviors. Individuals with other or unknown sexual orientation had significantly higher rates of suicidal behaviors compared to those with a heterosexual sexual orientation (ORs: 5.021, 95 % CI: 1.529-17.640). LIMITATIONS: Sampling of HIV-positive MSM posed challenges in data collection. It may introduce selection bias and affect generalizability. CONCLUSION: This study identified that sexual orientation, stigma, interpersonal needs, depression, and entrapment were significantly associated with suicidal behaviors among HIV-positive MSM. Additionally, these factors can be social determinants of health that contribute to suicidal behaviors.


Assuntos
Homossexualidade Masculina , Determinantes Sociais da Saúde , Estigma Social , Ideação Suicida , Humanos , Masculino , Adulto , Homossexualidade Masculina/estatística & dados numéricos , Homossexualidade Masculina/psicologia , China/epidemiologia , Fatores de Risco , Infecções por HIV/epidemiologia , Infecções por HIV/psicologia , Inquéritos e Questionários , Depressão/epidemiologia , Depressão/psicologia , Adulto Jovem , Tentativa de Suicídio/estatística & dados numéricos , Minorias Sexuais e de Gênero/estatística & dados numéricos , Minorias Sexuais e de Gênero/psicologia , Suicídio/estatística & dados numéricos , Suicídio/psicologia , Comportamento Sexual/estatística & dados numéricos , Comportamento Sexual/psicologia
5.
BJPsych Open ; 10(2): e41, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38297498

RESUMO

BACKGROUND: COVID-19 carriers experience psychological stresses and mental health issues such as varying degrees of stigma. The Social Impact Scale (SIS) can be used to measure the stigmatisation of COVID-19 carriers who experience such problems. AIMS: To evaluate the reliability and validity of the Chinese version of the SIS, and the association between stigma and depression among asymptomatic COVID-19 carriers in Shanghai, China. METHOD: A total of 1283 asymptomatic COVID-19 carriers from Shanghai Ruijin Jiahe Fangcang Shelter Hospital were recruited, with a mean age of 39.64 ± 11.14 years (59.6% male). Participants completed questionnaires, including baseline information and psychological measurements, the SIS and Self-Rating Depression Scale. The psychometrics of the SIS and its association with depression were examined through exploratory factor analysis, confirmatory factor analysis and receiver operating characteristic analysis. RESULTS: The average participant SIS score was 42.66 ± 14.61 (range: 24-96) years. Analyses suggested the model had four factors: social rejection, financial insecurity, internalised shame and social isolation. The model fit statistics of the four-factor SIS were 0.913 for the comparative fit index, 0.902 for the Tucker-Lewis index and 0.088 for root-mean-square error of approximation. Standard estimated factor loadings ranged from 0.509 to 0.836. After controlling for demographic characteristics, the total score of the 23-item SIS predicted depression (odds ratio: 1.087, 95% CI 1.061-1.115; area under the curve: 0.84, 95% CI 0.788-0.892). CONCLUSIONS: The Chinese version of the SIS showed good psychometric properties and can be used to assess the level of perceived stigma experienced by asymptomatic COVID-19 carriers.

6.
Sci Total Environ ; 895: 165045, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37355126

RESUMO

The behavior and removal of sulfamethoxazole (SMX) and 3 typical corresponding antibiotic resistance genes (ARGs) including sul1, sul2, sul3, and 16S rDNA in surface water were investigated in the photocatalyst-loading bionic ecosystems (PCBEs). Synthesized composite photocatalyst g-C3N4/TiO2 showing higher catalytic activity than Fe/g-C3N4/TiO2 was selected in the PCBEs. Five PCBEs, i.e., A-the control (without bionic grass or photocatalyst), B-bionic grass loaded with 4.12 g/m2 g-C3N4/TiO2, C-bionic grass loaded with 8.25 g/m2 g-C3N4/TiO2, D-bionic grass loaded with 12.37 g/m2 g-C3N4/TiO2, and E-bionic grass loaded with 16.5 g/m2 g-C3N4/TiO2 were constructed and operated in a medium-scale running cyclical flume. SMX could be photolyzed efficiently by g-C3N4/TiO2 with an optimal unit load on the bionic grass of 12.37 g/m2. 3-amino-5-methylisooxazole and p-aminobenzene sulfonamide were selected as main intermediates through the analyses of SMX degradation mechanisms and pathways, and detected in the aqueous phase and bionic grass. The intermediates were higher in the underwater part of the bionic grass than the above-water part. The overall removal of SMX ranged from 31.7 % to 82.3 % in 5 PCBEs, and the removal of sul1and sul2 were 0.2 %- 62.9 % in the aqueous phase and 8.4 %-63.2 % in the sediment. PCBE D might be the best construction when SMX and ARGs' removal was considered comprehensively. Moreover, the microbial structures showed Proteobacteria as the most dominant bacterial species had a relative abundance of 22.2 %-26.6 % and 33.4 %-68.2 % in the aquatic phase and sediment respectively, illustrating that the removal of the antibiotic and ARGs was bound up with the variations of dominant bacteria in the ecosystems. The findings illustrated that ecosystems with bionic grass and photocatalysts could be a promising technology for the removal of typical antibiotics and ARGs from surface water.


Assuntos
Antibacterianos , Sulfametoxazol , Sulfametoxazol/química , Água , Ecossistema , Biônica , Bactérias/genética , Resistência Microbiana a Medicamentos/genética
8.
Front Public Health ; 10: 1070334, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36620248

RESUMO

Introduction: Men who have sex with men (MSM) are a high-risk group for suicide, with a much higher prevalence of suicidal ideation (SI) than the general population and male population. The aim of this study was to explore the risk factors influencing the development of SI and to develop and validate a nomogram among MSM. Methods: A cross-sectional study was conducted in 915 MSM from Shanghai, Shenyang, Shenzhen and Kunming, China using the snowball sampling method. The integrated motivational-volitional (IMV) model of suicidal behavior was used as a theoretical framework to collect different potential influencing factors of SI including diathesis-environment-life events factors and psychosocial factors. The risk factors of SI were screened by logistic regression analysis, and a nomogram for predicting SI were developed. Model properties including discrimination, calibration and decision curves were evaluated to validate the prediction model. Results: 882 MSM were included in the statistical analysis, with a lifetime prevalence of SI of 34.4% (303/882). Logistic regression analysis showed that age group, sexual orientation disclosure, high-risk sexual behavior, entrapment, defeat and interpersonal needs were associated with SI. A nomogram was constructed based on the above six predictors. AUC values of ROC for prediction model were 0.761 (0.641-0.770) and 0.754 (0.565-0.822) in the training set (n = 662) and validation set (n = 220), respectively. And there was no statistical difference of the AUC values between the two sets (P > 0.05). The calibration plots of the prediction model in both sets fit well with the ideal model (P > 0.05). The decision curves demonstrated that the threshold probability of prediction model in training set was 1-85%, whereas in validation set was 1-63%. Conclusions: The lifetime prevalence of SI among Chinese MSM is high. The nomogram can serve as a useful tool to predict the development of SI among MSM. Defeat, entrapment and interpersonal needs, as significant predictors of SI, can be measured to identify SI in advance. Early assessment of SI and the enhancement of psychosocial interventions are important to prevent suicide-related behaviors. Future studies could incorporate more variables of interest to refine the prediction model to better guide behavioral and psychological intervention strategies among MSM.


Assuntos
Minorias Sexuais e de Gênero , Ideação Suicida , Humanos , Masculino , Feminino , Homossexualidade Masculina/psicologia , Estudos Transversais , Nomogramas , China/epidemiologia
9.
Water Res ; 200: 117234, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34058485

RESUMO

Advanced oxidation processes (AOPs) have received a lot of attention over the years as advanced physico-chemical polishing wastewater treatments to remove biorefractory pollutants. Additionally, many studies report their excellent degradation and mineralization performance as stand-alone technologies too, demonstrating the versatility of these processes; however, there is a lack of suitable methods to compare the performance (in terms of removal efficiency and operating costs) of different AOPs in the same conditions. In this context, the goal of this paper is to propose a systematic investigation by introducing a novel criterion, namely the accumulated oxygen-equivalent chemical-oxidation dose (AOCD), to systematically compare the diverse AOPs available: ozonation, H2O2 photolysis, Fenton, photo-Fenton, electro-Fenton and photoelectro-Fenton (paired with anodic oxidation, for the latter two). For each of these, the cost efficiency was determined by optimizing the operating conditions for the removal of phenol, selected as a model pollutant (1.4 mM, equivalent to 100 mg-C L-1). The operating costs considered sludge management, chemical use and electricity consumption. Among all AOPs, electro-Fenton was the most cost-effective (108 - 125 € m-3), notwithstanding the mineralization target (50%, 75% and 99%), owing to its electrocatalytic behavior. Chemical Fenton proved competitive too up to 50% of mineralization, meaning that it could also be considered as a cost-effective pre-treatment solution. AOCD was the lowest for electro-Fenton, which could be attributed to its excellent faradaic yield, while UV-based processes generally required the highest dose. The AOCD criterion could serve as a baseline for AOP comparison and prove useful for the legislator to determine the "best available techniques" as defined by the Industrial Emissions European Union Directive 2010/75/EU.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Custos e Análise de Custo , Peróxido de Hidrogênio , Ferro , Oxirredução , Oxigênio
10.
Biomater Sci ; 9(10): 3821-3829, 2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-33881045

RESUMO

The Tibetan eighteen flavor dangshen pills (TEP) are composed of 18 traditional Tibetan medicines, which are commonly used in the treatment of skin diseases in the Tibetan medical system. They have anti-inflammatory and analgesic effects, and healing properties. However, TEP contain large doses and have strong side effects and low bioavailability. To improve the utilization rate of TEP in skin treatment, we prepared TEP powder and then introduced it into polyvinyl alcohol/chitosan (PVA/CS) hydrogels to treat diabetic wounds by slowly releasing the active ingredients of TEP. In vitro studies showed that TEP-loaded hydrogels can effectively and continuously release the active ingredients of TEP and have antibacterial and antioxidant properties. In addition, the hydrogel system was not cytotoxic to L929 cells, and significantly promoted the proliferation of HUVECs. Moreover, when the TEP-loaded hydrogel was applied to diabetic wounds in rats, it reduced the inflammatory response and improved collagen deposition, which in turn promoted skin healing. Our results indicate that TEP-loaded hydrogels may be a new formulation for the application of traditional Tibetan medicines for the treatment of chronic wounds.


Assuntos
Quitosana , Diabetes Mellitus , Animais , Preparações de Ação Retardada , Hidrogéis , Medicina Tradicional Tibetana , Álcool de Polivinil , Ratos , Cicatrização
11.
Environ Sci Technol ; 55(4): 2564-2574, 2021 02 16.
Artigo em Inglês | MEDLINE | ID: mdl-33502180

RESUMO

Electro-Fenton (EF) is an emerging technology with well-known outstanding oxidation power; yet, its application to the treatment of inorganic contaminants has been largely disregarded. Thiosalts are contaminants of emerging concern in mine water, responsible for delayed acidity in natural waterways. In this study, EF was used to treat thiosalts in synthetic and real mine water. Thiosulfate (S2O32-) solutions were first used to optimize the main parameters affecting the process, namely, the current density (2.08-6.25 mA cm-2), temperature (4 vs 20 °C), and S2O32- concentration (0.25-2 g L-1). S2O32- was almost completely removed in 2 h of treatment at 6.25 mA cm-2, while temperature played no important role in the process efficiency. The optimal conditions were then applied to treat a real sample of contaminated mine water, resulting in complete S2O32- and S4O62- oxidation to SO42- in 90 min at 6.25 mA cm-2 (95% removal in only 60 min). The reaction mechanisms were investigated in detail based on the quantification of the main degradation byproducts. This study opens new possibilities for EF application to the treatment of thiosalt-contaminated mine water and other oxidizable inorganic-impacted wastewaters.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Eletrodos , Peróxido de Hidrogênio , Oxirredução , Águas Residuárias , Água
12.
Macromol Biosci ; 20(12): e2000069, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32864834

RESUMO

In this study, a novel cyclodextrin derivative, i.e., zwitterionic choline phosphate (CP)-functionalized ß-cyclodextrin (CP-ß-CD) is successfully synthesized by click chemistry reaction. CP-ß-CD has excellent cell-membrane-targeted ability because of the CP group can bind to phosphate choline (PC) in the cell membrane and promote the cellular uptake. Due to the introduction of CP group on ß-CD, it disrupts the hydrogen network between natural ß-CD molecules. Meanwhile, the water solubility of CP-ß-CD is improved dramatically to 816 mg mL-1 , which is 440 times as that of unmodified ß-CD. Apatinib, a small molecular inhibitor, is used as a model of hydrophobic drug and loaded into CP-ß-CD to study the solubilization effect and the anti-angiogenisis activity. In addition, the cytotoxicity of CP-ß-CD is also studied, and it is demonstrated that CP-ß-CD is nontoxic. These results indicate that the apatinib can be transported into cell interior and play an excellent anti-angiogenisis activity after being loaded into CP-ß-CD drug delivery system. This work suggests that the water soluble CP-ß-CD with excellent cell internalization efficiency has a potential application prospect in the field of drug delivery.


Assuntos
Membrana Celular/efeitos dos fármacos , Portadores de Fármacos/farmacologia , Sistemas de Liberação de Medicamentos , Fosforilcolina/química , Membrana Celular/química , Portadores de Fármacos/química , Humanos , Solubilidade , Água/química , beta-Ciclodextrinas/química
13.
Colloids Surf B Biointerfaces ; 185: 110630, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31740325

RESUMO

In this study, the surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-(methacryloyloxy) ethyl choline phosphate (MCP) was successfully carried out via the ATRP initiator immobilized on the surfaces of polylactic acid (PLA) films. Different amounts of PMCP polymer brushes were constructed on the PLA surface to investigate the effects of the biological and degradation properties before and after modification. The results showed that the hydrophilicity of the surface of PLA were improved by MCP modification. In addition, there are no significant influence on the structure and crystallinity of the film before and after modification, except for the increased slightly thermal stability. Since the PMCP polymer brush forms a "protection" effect on the surface, the films showed an excellent property of resistant to hydrolysis even with obviously improved hydrophilicity. Furthermore, with the increase of the amount of introduced MCP monomer, the hydrophilicity and degradation resistance have been further improved. The in vivo animal experiment also verified this degradation resistance. Thereby, this strategy can be used to modulate the degradation rate of degradable polymers via surface modification.


Assuntos
Fosforilcolina/análogos & derivados , Poliésteres/química , Ácidos Polimetacrílicos/química , Fosforilcolina/química , Espectroscopia Fotoeletrônica , Propriedades de Superfície , Água/química
14.
J Hazard Mater ; 360: 552-559, 2018 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-30145482

RESUMO

For the first time, real effluents from the micro-electronics industry were treated by paired advanced electrocatalysis, combining electro-Fenton (EF) with anodic oxidation (AO). A detailed characterization of the effluents was performed, showing that isopropanol (IPA) and acetone were the main constituents of the wastewater. Both compounds were completely degraded during the first 120 min of treatment. By monitoring the degradation intermediates, an oxidation pathway was proposed, which includes short-chain carboxylic acids as the main end-organic compounds. While carbon brush served as the cathode, two anode materials were utilized: boron-doped diamond (BDD) and carbon-PTFE cloth (CC). Despite the lower mineralization efficiency showed by CC as compared to BDD (76.5% of TOC removal with CC vs 94.0% of TOC removal with BDD after 4 h), CC showed potential to increase the BOD5/COD ratio of the effluent that reached 0.7 after only 45 min (0.6 in 30 min with BDD). These results suggest that the electrolysis time could be kept short, improving the cost-effectiveness of the process, especially if CC is used. Overall, the results point out the suitability of advanced electrocatalysis to treat real electronics wastewater with low energy requirements, short treatment times and cost-effective electrode materials.


Assuntos
Técnicas Eletroquímicas , Resíduo Eletrônico , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , 2-Propanol/química , 2-Propanol/metabolismo , Acetona/química , Acetona/metabolismo , Biodegradação Ambiental , Boro/química , Catálise , Diamante/química , Eletrodos , Águas Residuárias , Poluentes Químicos da Água/metabolismo
15.
Wei Sheng Wu Xue Bao ; 55(10): 1273-83, 2015 Oct 04.
Artigo em Chinês | MEDLINE | ID: mdl-26939455

RESUMO

OBJECTIVE: To further study physiological functions and structure of ß-glycosidase, we cloned the bglC gene of Bacillus subtilis and expressed it in E. coli BL21 (DE3), followed by the characterization and structural simulation of the enzyme. METHODS: We amplified the bglC gene and transferred it into E. coli BL21 (DE3), then we obtained a mutant with higher hydrolytic activity by directed evolution. After purifying the enzymes through a nickel-nitrilotriacetic acid agarose column, we characterized the wild-type and mutant enzymes. By means of CD spectrum, Native-PAGE and protein 3-D structure modeling, we analyzed the higher structure of the ß-glycosidase. RESULTS: We got one mutant enzyme BS-GLY_M1 (A242T/T385A/S425L) with improved hydrolytic activity by directed evolution and screening. The specific activity of wild-type enzyme was 9.7 U/mg, with optimum temperature at 60 degrees C and optimum pH at 7.0. The specific activity of BS-GLY_M1 was 17. 1U/mg, with optimum temperature at 55 degrees C and optimum pH at 7.0. Moreover, the half-life time of the mutant enzyme at 55 degrees C was 3.5 h, 2 h longer than that of wild-type enzyme. Furthermore, the catalytic efficiency (K(m)/K(cat)) of BS-GLY_M1 on the substrates 4-nitrophenyl-ß-galactoside, lactose, and arbutin improved obviously. The polymer forms of the enzyme under the native conditions were of dimer and tetramer, but the dimer was the most probable functional unit. Result of structural simulation also showed slight changes occurred in the tertiary structure of the mutant enzyme, which may be the main reason for the enhanced thermal stability and catalytic efficiency of BS-GLY _M1. [ CONCLUSION: ß-glycosidase from Bacillus subtilis could be expressed in E. coli BL21 (DE3), meanwhile its hydrolysis efficiency could be further improved by directed evolution.


Assuntos
Bacillus subtilis/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Clonagem Molecular , beta-Galactosidase/química , beta-Galactosidase/genética , Bacillus subtilis/genética , Proteínas de Bactérias/metabolismo , Catálise , Evolução Molecular Direcionada , Estabilidade Enzimática , Escherichia coli/genética , Escherichia coli/metabolismo , Cinética , Modelos Moleculares , Temperatura , beta-Galactosidase/metabolismo
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