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2.
JMIR Res Protoc ; 10(10): e32085, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34609323

RESUMO

BACKGROUND: Reduced mobility and falls are common among older adults. Balance retraining programs are effective in reducing falls and in improving balance and mobility. Noisy galvanic vestibular stimulation is a low-level electrical stimulation used to reduce the threshold for the firing of vestibular neurons via a mechanism of stochastic resonance. OBJECTIVE: This study aims to determine the feasibility of using noisy galvanic vestibular stimulation to augment a balance training program for older adults at risk of falls. We hypothesize that noisy galvanic vestibular stimulation will enhance the effects of balance retraining in older adults at risk of falls. METHODS: In this 3-armed randomized controlled trial, community dwelling older adults at risk of falling will be randomly assigned to a noisy galvanic vestibular stimulation plus balance program (noisy galvanic vestibular stimulation group), sham plus balance program (sham group), or a no treatment group (control). Participants will attend the exercise group twice a week for 8 weeks with assessment of balance and gait pretreatment, posttreatment, and at 3 months postintervention. Primary outcome measures include postural sway, measured by center of pressure velocity, area and root mean square, and gait parameters such as speed, step width, step variability, and double support time. Spatial memory will also be measured using the triangle completion task and the 4 Mountains Test. RESULTS: Recruitment began in November 2020. Data collection and analysis are expected to be completed by December 2022. CONCLUSIONS: This study will evaluate the feasibility of using noisy galvanic vestibular stimulation alongside balance retraining in older adults at risk of falls and will inform the design of a fully powered randomized controlled trial. TRIAL REGISTRATION: New Zealand Clinical Trials Registry (ACTRN12620001172998); https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=379944. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/32085.

3.
Autism ; 25(3): 812-830, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-32907344

RESUMO

LAY ABSTRACT: Neurological disorders, such as epilepsy and cerebral palsy, have been reported to occur among individuals with autism beyond chance and may have an impact on daily living across the lifespan. Although there has been research investigating neurological disorders in autism, the findings are not always conclusive. Previous summaries of existing studies have not evaluated the full range of neurological disorders. This study aimed to comprehensively explore the neurological problems appearing in autism to provide updated information that is needed for better healthcare and support in this population. We looked at already published studies focusing on risk or frequency of neurological disorders in autism. Our results suggest that individuals with autism are more likely than the general population to have a range of neurological disorders, including epilepsy, macrocephaly, hydrocephalus, cerebral palsy, migraine/headache, and inborn abnormalities of the nervous system. In order to provide individualized healthcare and support of high quality to individuals diagnosed with autism, health care professionals and other support providers need to be attentive to neurological complications. To further improve our understanding about the link between autism and neurological disorders, future research should follow the neurological health of children who are diagnosed with or are at increased likelihood of autism.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Epilepsia , Transtorno do Espectro Autista/epidemiologia , Transtorno Autístico/epidemiologia , Criança , Epilepsia/epidemiologia , Humanos
4.
Indian J Med Microbiol ; 38(2): 200-209, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32883934

RESUMO

Purpose: Enterococci express high degree of resistance towards wide range of antibiotics. Production of biofilm and many virulence factors along with drug resistance makes it difficult to eradicate the infection from urinary tract. The present study detected the expression of such factors including biofilm production by multidrug-resistant (MDR) enterococci. Materials and Methods: Drug susceptibility of 103 uropathogenic enterococci was performed followed by estimation of minimum inhibitory concentration of high-level gentamicin and vancomycin by microbroth dilution method. Vancomycin-resistant genes were detected by multiplex polymerase chain reaction. Production of virulence factors such as haemagglutination, caseinase, lipase, gelatinase, haemolysin and ß-lactamase was detected by phenotypic methods in MDR strains. Biofilm production was detected by calcofluor-white fluorescence staining and semi-quantitative adherence assay. Results: 45% and 18.4% of the isolates were high-level gentamicin-resistant and vancomycin-resistant enterococci (VRE), respectively. vanA gene was detected in 14 and vanB gene in 5 strains. Biofilm, caseinase and gelatinase were the most expressed virulence factor. Expression of caseinase, gelatinase and lipase was significantly higher in Enterococcus faecalis (P < 0.05). Expression of haemagglutination, gelatinase and haemolysin among the vancomycin-resistant isolates was significantly higher (P < 0.05). Conclusion: VanA and vanB are the prevalent genotypes responsible for vancomycin resistance. The high prevalence of MDR enterococcal strains producing biofilm and virulence determinants raises concern. asa1, hyl, esp, gelE, cyl and other genes are known to express these factors and contribute to biofilm formation. Most uropathogenic enterococci expressed biofilm at moderate level and can be detected effectively by calcofluor-white staining. No correlation was noted between vancomycin resistance and biofilm production.


Assuntos
Biofilmes/crescimento & desenvolvimento , Enterococcus faecium/patogenicidade , Infecções por Bactérias Gram-Positivas/microbiologia , Infecções Urinárias/microbiologia , Enterococos Resistentes à Vancomicina/patogenicidade , Fatores de Virulência/biossíntese , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Carbono-Oxigênio Ligases/genética , Estudos Transversais , Farmacorresistência Bacteriana Múltipla , Enterococcus/efeitos dos fármacos , Enterococcus/isolamento & purificação , Enterococcus/metabolismo , Enterococcus/patogenicidade , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/isolamento & purificação , Enterococcus faecalis/metabolismo , Enterococcus faecalis/patogenicidade , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/isolamento & purificação , Enterococcus faecium/metabolismo , Genes Bacterianos , Humanos , Índia , Testes de Sensibilidade Microbiana , Resistência a Vancomicina/genética , Enterococos Resistentes à Vancomicina/genética , Enterococos Resistentes à Vancomicina/isolamento & purificação , Enterococos Resistentes à Vancomicina/fisiologia , Virulência/genética , Fatores de Virulência/genética
5.
Anticancer Res ; 40(2): 751-758, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32014917

RESUMO

BACKGROUND/AIM: This study investigated a novel combined therapy of rosmarinic acid (RA)/blue light on head and neck squamous cell carcinoma (HNSCC) cell proliferation in vitro. MATERIALS AND METHODS: HNSCC cells were exposed to BL (500 mW/cm2) for 90 s, and incubated with 80 µg/ml RA for 1 hour. Cell viability was determined after 24 h using WST-1 assay. Western blot was used to detect treatment-induced changes in epidermal growth factor receptor (EGFR) activation. Hydrogen peroxide (H2O2) and nitric oxide levels were quantified using CM-H2DCFH-DA assays. Apoptosis was assessed using Annexin V/PI staining and flow cytometry. RESULTS: RA/blue light treatment resulted in a significant reduction in cell viability, EGFR activation and H2O2 levels in all HNSCC cell lines. However, no significant changes in NO production or apoptosis induction were found. CONCLUSION: RA/blue light effectively decreased HNSCC cell proliferation through reduction in EGFR activation and H2O2 production, and not via induction of apoptosis.


Assuntos
Cinamatos/farmacologia , Depsídeos/farmacologia , Neoplasias de Cabeça e Pescoço/terapia , Fototerapia/métodos , Carcinoma de Células Escamosas de Cabeça e Pescoço/terapia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Terapia Combinada , Ativação Enzimática/efeitos dos fármacos , Receptores ErbB/metabolismo , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Óxido Nítrico/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Carcinoma de Células Escamosas de Cabeça e Pescoço/tratamento farmacológico , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Ácido Rosmarínico
6.
J Immunol Res ; 2018: 9585614, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29725606

RESUMO

Cancer is a condition that has plagued humanity for thousands of years, with the first depictions dating back to ancient Egyptian times. However, not until recent decades have biological therapeutics been developed and refined enough to safely and effectively combat cancer. Three unique immunotherapies have gained traction in recent decades: adoptive T cell transfer, checkpoint inhibitors, and bivalent antibodies. Each has led to clinically approved therapies, as well as to therapies in preclinical and ongoing clinical trials. In this review, we outline the method by which these 3 immunotherapies function as well as any major immunotherapeutic drugs developed for treating a variety of cancers.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Imunoterapia/métodos , Neoplasias/terapia , Linfócitos T/imunologia , Animais , Ensaios Clínicos como Assunto , Receptores Coestimuladores e Inibidores de Linfócitos T/imunologia , Humanos , Neoplasias/imunologia , Linfócitos T/transplante
7.
3 Biotech ; 7(5): 346, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28955643

RESUMO

The insecticidal potential of cells and acid-precipitated biomolecules (APB) of Bacillus vallismortis (Roberts) (Bacillales: Bacillaceae) R2 was evaluated against polyphagous pest Spodoptera litura. The intact cells of isolate R2 and its APB preparation significantly increased larval mortality. Both cells and APB significantly delayed the development and reduced adult emergence of S. litura. The toxicity of isolate R2 was evident from the emergence of morphologically deformed adults with crumpled and underdeveloped wings. The nutritional physiology of larvae fed on APB-supplemented diet was also adversely affected resulting in significant reduction of relative growth and consumption rate as well as efficiency of conversion of ingested and digested food. Thus, the intact viable cells and APB of B. vallismortis R2 may serve as environmental-friendly alternatives to chemical insecticides.

8.
PLoS One ; 11(3): e0150764, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26953696

RESUMO

Ribose-5-phosphate isomerase B from Leishmania donovani (LdRpiB) is one of the potential drug targets against visceral leishmaniasis. In the present study, we have targeted several conserved amino acids for mutational analysis (i.e. Cys69, His11, His102, His138, Asp45, Tyr46, Pro47 and Glu149) to gain crucial insights into their role in substrate binding, catalysis and conformational stability of the enzyme. All the eight LdRpiB variants were cloned, sequenced, expressed and purified. C69S, H102N, D45N and E149A mutants exhibited complete loss of enzyme activity indicating that they are indispensable for the enzyme activity. Kinetic parameters were altered in case of H138N, H11N and P47A variants; however Y46F exhibited similar kinetic behaviour as wild type. All the mutants except H138N exhibited altered protein structure as determined by CD and fluorescence spectral analysis. This data was supported by the atomic level details of the conformational changes and substrate binding using molecular dynamic simulations. LdRpiB also exhibited activity with D-form of various aldose substrates in the order of D-ribose > D-talose > D-allose > D-arabinose. Our study provides insights for better understanding of substrate enzyme interactions which can rationalize the process of drug design against parasite RpiB.


Assuntos
Aldose-Cetose Isomerases/química , Aldose-Cetose Isomerases/genética , Sequência Conservada , Leishmania donovani/genética , Leishmania donovani/metabolismo , Modelos Moleculares , Mutação , Aldose-Cetose Isomerases/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Cinética , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Dados de Sequência Molecular , Ligação Proteica , Conformação Proteica , Alinhamento de Sequência , Relação Estrutura-Atividade , Especificidade por Substrato
9.
Appl Biochem Biotechnol ; 173(7): 1870-84, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24907042

RESUMO

Ribose-5-phosphate isomerase B (RpiB), a crucial enzyme of pentose phosphate pathway, was proposed to be a potential drug target for visceral leishmaniasis. In this study, we have analyzed the biophysical properties of Leishmania donovani RpiB (LdRpiB) enzyme to gain insight into its unfolding pathway under various chemical and thermal denaturation conditions by using fluorescence and CD spectroscopy. LdRpiB inactivation precedes the structural transition at lower concentrations of both urea and guanidine hydrochloride (GdHCl). 8-Anilinonapthalene 1-sulfonic (ANS) binding experiments revealed the presence of molten globule intermediate at 1.5 M GdHCl and a nonnative intermediate state at 6-M urea concentration. Acrylamide quenching experiments further validated the above findings, as solvent accessibility of tryptophan residues increased with increase in GdHCl and urea concentration. The recombinant LdRpiB was completely unfolded at 6 M GdHCl, whereas the enzyme molecule was resistant to complete unfolding even at 8-M urea concentration. The GdHCl- and urea-mediated unfolding involves a three-state transition process. Thermal-induced denaturation revealed complete loss of enzyme activity at 65 °C with only 20 % secondary structure loss. The formation of the well-ordered ß-sheet structures of amyloid fibrils was observed after 55 °C which increased linearly till 85 °C as detected by thioflavin T dye. This study depicts the stability of the enzyme in the presence of chemical and thermal denaturants and stability-activity relationship of the enzyme. The presence of the intermediate states may have major implications in the way the enzyme binds to its natural ligand under various conditions. Also, the present study provides insights into the properties of intermediate entities of this important enzyme.


Assuntos
Aldose-Cetose Isomerases/química , Leishmania donovani/enzimologia , Desdobramento de Proteína/efeitos dos fármacos , Temperatura , Triptofano , Aldose-Cetose Isomerases/metabolismo , Estabilidade Enzimática/efeitos dos fármacos , Guanidina/farmacologia , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Ureia/farmacologia
10.
J Obstet Gynaecol India ; 64(3): 175-9, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24966500

RESUMO

OBJECTIVES: To study oxytocin, misoprostol, and methylergometrine in active management of the third stage of labor and determine duration of the third stage of labor, blood loss, adverse effects, and need for additional uterotonics in each group. METHODS: Clinical trial of 300 women with healthy singleton pregnancy allocated into three groups to receive either: 10 IU intravenous oxytocin infusion, 600 µg sublingual misoprostol, or 200 µg intravenous methylergometrine. Primary outcome measure was blood loss in the third stage of labor; secondary measures were duration of the third stage, side effects, and complications. RESULTS: Subjects who received 600 µg of misoprostol had the least blood loss, followed by oxytocin, and methylergometrine. The shortest mean duration of the third stage was with misoprostol. Shivering and pyrexia were observed in misoprostol group, and raised blood pressure in methylergometrine group. CONCLUSIONS: Misoprostol is as effective as oxytocin and both are more effective than methylergometrine in active management of the third stage of labor.

11.
Exp Parasitol ; 144: 84-90, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24950381

RESUMO

In the present study, we have investigated the antileishmanial potential of mianserin, an antidepressant. Mianserin was found to inhibit both the promastigote and amastigote forms of the parasite in a dose dependant manner. The IC50 values for promastigotes and amastigotes were 21 µM and 46 µM respectively. Interestingly, mianserin failed to inhibit THP-1 differentiated macrophages up to 100 µM concentration thus, exhibiting parasite selectivity. When mianserin was incubated with recombinant Leishmania donovani 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) enzyme, it exhibited an IC50 value of 19.8 µM. Inhibition kinetics revealed competitive mode of enzyme inhibition as the Km increased with no change in Vmax. Further structural investigation of enzyme-inhibitor interaction revealed quenching of HMGR tryptophan intrinsic fluorescence with a K(sv) value of 3.025±0.37 M(-1) and an apparent binding constant of 0.0954 mM. We further estimated ergosterol levels which is a major component of Leishmania cell membrane. It is synthesized by HMGR enzyme, the first rate limiting enzyme of the sterol biosynthetic pathway. Analysis of ergosterol levels by HPLC revealed ∼2.5-fold depletion in mianserin treated promastigotes with respect to untreated parasites. This data was further validated by exogenous supplementation of mianserin treated cells with ergosterol and cholesterol. Reversal of growth inhibition was observed only upon ergosterol addition though it was refractory to cholesterol supplementation. Overall, our results demonstrate the possibility of repositioning of an antidepressant for the treatment of Visceral Leishmaniasis.


Assuntos
Antiprotozoários/farmacologia , Ergosterol/metabolismo , Leishmania donovani/efeitos dos fármacos , Mianserina/farmacologia , Animais , Antidepressivos de Segunda Geração/química , Antidepressivos de Segunda Geração/farmacologia , Antiprotozoários/química , Linhagem Celular , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta a Droga , Hidroximetilglutaril-CoA Redutases/efeitos dos fármacos , Hidroximetilglutaril-CoA Redutases/metabolismo , Concentração Inibidora 50 , Leishmania donovani/crescimento & desenvolvimento , Leishmania donovani/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologia , Mianserina/química , Espectrometria de Fluorescência
12.
Z Naturforsch C J Biosci ; 69(3-4): 110-6, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24873031

RESUMO

The antileishmanial activity of extracts and phytoconstituents of Moringa oleifera Lam. was investigated in vitro against promastigotes of Leishmania donavani. The 70% ethanolic extract of roots and the methanolic extract of leaves showed moderate inhibitory activity with IC50 values of 83.0 microg/ml and 47.5 microg/ml, respectively. Antileishmanial activity of the methanolic extract of leaves increased upon fractionation, as its ethyl acetate fraction was found to be more active with an IC50 value of 27.5 microg/ml. The most active antileishmanial compound niazinin, a thiocarbamate glycoside isolated from this fraction, showed an IC50 value of 5.25 microM. Results presented in this study indicate that extracts from M. oleifera may be developed as an adjuvant therapy for the treatment of leishmaniasis.


Assuntos
Leishmania/efeitos dos fármacos , Moringa oleifera/química , Extratos Vegetais/farmacologia , Tripanossomicidas/farmacologia , Animais , Linhagem Celular , Humanos , Concentração Inibidora 50
13.
Parasitol Res ; 113(6): 2161-8, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24728519

RESUMO

Leishmaniasis is one of the major health problems existing globally. The current chemotherapy for leishmaniasis presents several drawbacks like toxicity and increased resistance to existing drugs, and hence, there is a necessity to look out for the novel drug targets and new chemical entities. Current trend in drug discovery arena is the "repurposing" of old drugs for the treatment of diseases. In the present study, an antidepressant, ketanserin, was found lethal to both Leishmania donovani promastigotes and intracellular amastigotes with no apparent toxicity to the cells. Ketanserin killed promastigotes and amastigotes with an IC50 value of 37 µM and 28 µM respectively, in a dose-dependent manner. Ketanserin was found to inhibit L. donovani recombinant 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) enzyme with an IC50 value of 43 µM. Ketanserin treated promastigotes were exogenously supplemented with sterols like ergosterol and cholesterol to rescue cell death. Ergosterol could recover the inhibition partially, whereas cholesterol supplementation completely failed to rescue the inhibited parasites. Further, HMGR-overexpressing parasites were generated by transfecting Leishmania promastigotes with an episomal pspα hygroα-HMGR construct. Wild-type and HMGR overexpressors of L. donovani were used to study the effect and mode of action of this inhibitor. The HMGR overexpressors showed twofold resistance to ketanserin. These observations suggest that the lethal effect of ketanserin is due to inhibition of HMGR, the rate-limiting enzyme of the ergosterol biosynthetic pathway. Since targeting of the sterol biosynthetic pathway enzymes may be useful therapeutically, the present study may have implications in treatment of leishmaniasis.


Assuntos
Antidepressivos/farmacologia , Hidroximetilglutaril-CoA Redutases/metabolismo , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Ketanserina/farmacologia , Leishmania donovani/efeitos dos fármacos , Coenzimas/farmacologia
14.
Microb Pathog ; 66: 14-23, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24239940

RESUMO

3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase (HMGR), an NADPH dependant enzyme catalyzes the synthesis of mevalonic acid from HMG-CoA required for isoprenoid biosynthesis. The HMGR gene from Leishmania donovani was cloned and expressed. Genome analysis of L. donovani revealed that HMGR gene having an open reading frame of 1305 bp encodes a putative protein of 434 amino acids. LdHMGR showed optimal activity at pH 7.2 and temperature 37 °C. Kinetic analysis of this enzyme revealed Km values of 35.7 ± 2.5 µM for (R,S)-HMG-CoA and 70 ± 7.9 µM for the cofactor NADPH. On tryptophan fluorescence quenching, the Stern Volmer constant (Ksv), binding constant (Ka) and protein:cofactor stoichiometry for interaction of NADPH cofactor with the enzyme were found to be 6.0 ± 0.7 M(-1), 0.17 µM and 0.72 respectively. Polyclonal anti-rat HMGR antibody detected a band of ∼45 kDa in all phases of promastigote growth. Biophysical analysis of the secondary structure of LdHMGR confirmed the presence of 25.7 ± 0.35% alpha helicity. Thermal denaturation studies showed extreme stability of the enzyme with 60% helical structure retained at 90 °C. Statins (simvastatin and atorvastatin) and non-statin (resveratrol) effectively inhibited the growth of L. donovani promastigotes as well as the catalytic activity of the recombinant LdHMGR. Atorvastatin was found to be most potent antileishmanial inhibitor with an IC50 value of 19.4 ± 3.07 µM and a very lower concentration of 315.5 ± 2.1 nM was enough to cause 50% recombinant LdHMGR enzyme inhibition suggesting direct interaction with the rate limiting enzyme of the ergosterol biosynthetic pathway. Exogenous supplementation of ergosterol in case of atorvastatin and resveratrol treated cells caused complete reversal of growth inhibition whereas simvastatin was found to be ergosterol refractory. Cholesterol supplementation however, failed to overcome growth inhibition in all the cases. Overall our study emphasizes on exploring LdHMGR as a potential drug target for the development of novel antileishmanial agents.


Assuntos
Regulação Enzimológica da Expressão Gênica , Genes de Protozoários , Hidroximetilglutaril-CoA Redutases/metabolismo , Leishmania donovani/enzimologia , Sequência de Aminoácidos , Atorvastatina , Colesterol/metabolismo , Clonagem Molecular , DNA de Protozoário/genética , Sistemas de Liberação de Medicamentos , Ergosterol/metabolismo , Ácidos Heptanoicos/farmacologia , Hidroximetilglutaril-CoA Redutases/genética , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Leishmania donovani/efeitos dos fármacos , Leishmania donovani/genética , Dados de Sequência Molecular , Fases de Leitura Aberta , Estrutura Secundária de Proteína , Pirróis/farmacologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Resveratrol , Análise de Sequência de DNA , Sinvastatina/farmacologia , Estilbenos/farmacologia
15.
Biochem Biophys Res Commun ; 421(1): 51-6, 2012 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-22483752

RESUMO

Leishmaniasis is a group of tropical diseases caused by protozoan parasites of the genus Leishmania. Due to the emergence of resistance to the available antileishmanial drugs there is an immediate need to identify molecular targets on which to base future treatment strategies. Ribose 5-phosphate isomerase (Rpi; EC 5.3.1.6) is a key enzyme of the pentose phosphate pathway (PPP) which catalyses the reversible aldose-ketose isomerization between Ribose 5-phosphate (R5P) and Ribulose 5-phosphate (Ru5P). It exists in two isoforms A and B. These two are completely unrelated enzymes catalyzing the same reaction. Analysis of the Leishmania infantum genome revealed that though the RpiB gene is present, RpiA homologs are completely absent. An absence of RpiBs in the genomes of higher animals makes this enzyme a possible target for the chemotherapy of Leishmaniasis. In this paper, we report for the first time the presence of B isoform of the Rpi enzyme in Leishmania donovani (LdRpiB) by cloning and molecular characterization of the enzyme. An amplified L. donovani RpiB gene is 519 bp and encodes for a putative 172 amino acid protein with a molecular mass of ∼19 kDa. An ∼19 kDa protein with poly-His tag at the C-terminal end was obtained by heterologous expression of LdRpiB in Escherichia coli. The recombinant form of RpiB was obtained in soluble and active form. The LdRpiB exists as a dimer of dimers i.e. the tetramer form. The polyclonal antibody against Trypanosoma cruzi RpiB could detect a band of ∼19 kDa with the purified recombinant RpiB as well as native RpiB from the L. donovani promastigotes. Recombinant RpiB obeys the classical Michaelis-Menten kinetics utilizing R5P as the substrate with a K(m) value of 2.4±0.6 mM and K(cat) value of 30±5.2 s(-1). Our study confirms the presence of Ribose 5-phosphate isomerase B in L. donovani and provides functional characterization of RpiB for further validating it as a potential drug target.


Assuntos
Aldose-Cetose Isomerases/química , Leishmania donovani/enzimologia , Proteínas de Protozoários/química , Aldose-Cetose Isomerases/genética , Aldose-Cetose Isomerases/isolamento & purificação , Sequência de Aminoácidos , Cinética , Dados de Sequência Molecular , Peso Molecular , Proteínas de Protozoários/genética , Proteínas de Protozoários/isolamento & purificação , Proteínas Recombinantes/química , Proteínas Recombinantes/classificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação
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