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1.
NPJ Breast Cancer ; 10(1): 29, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38637568

RESUMO

Tumor-infiltrating lymphocytes (TILs) have been associated with outcomes in HER2-positive breast cancer patients treated with neoadjuvant chemotherapy and trastuzumab. However, it remains unclear if TILs could be a prognostic and/or predictive biomarker in the context of dual HER2-targeting treatment. In this study, we evaluated the association between TILs and pathological response (pCR) and invasive-disease free survival (IDFS) in 389 patients with stage II-III HER2 positive breast cancer who received neoadjuvant anthracycline-containing or anthracycline-free chemotherapy combined with trastuzumab and pertuzumab in the TRAIN-2 trial. Although no significant association was seen between TILs and pCR, patients with TIL scores ≥60% demonstrated an excellent 3-year IDFS of 100% (95% CI 100-100), regardless of hormone receptor status, nodal stage and attainment of pCR. Additionally, in patients with hormone receptor positive disease, TILs as a continuous variable showed a trend to a positive association with pCR (adjusted Odds Ratio per 10% increase in TILs 1.15, 95% CI 0.99-1.34, p = 0.070) and IDFS (adjusted Hazard Ratio per 10% increase in TILs 0.71, 95% CI 0.50-1.01, p = 0.058). We found no interactions between TILs and anthracycline treatment. Our results suggest that high TIL scores might be able to identify stage II-III HER2-positive breast cancer patients with a favorable prognosis.

2.
Hum Exp Toxicol ; 36(6): 565-572, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27473018

RESUMO

Di-(2-ethylhexyl) phthalate (DEHP) is the most common plasticizer used in polyvinyl chloride-based plastics. DEHP is not covalently bound to the plastics and is easily released to the environment, resulting in human exposure. In this study, the adult rats were exposed to DEHP and its effects on the uterus was evaluated. Healthy adult female rats were treated with DEHP orally (with dose level 0, 1, 10, and 100 mg/kg body weight/day) for 30 days. No significant changes in the body weight and wet uterine weight were observed. Ovarian hormones and their receptor levels in the uterus were increased. Histological studies exhibited the structural abnormalities such as decrease in diameter, thinning of the layers and disruption in the glandular epithelium.


Assuntos
Dietilexilftalato/toxicidade , Plastificantes/toxicidade , Útero/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Estradiol/sangue , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/genética , Receptor beta de Estrogênio/metabolismo , Feminino , Tamanho do Órgão/efeitos dos fármacos , PPAR gama/genética , PPAR gama/metabolismo , Progesterona/sangue , RNA Mensageiro/metabolismo , Ratos Wistar , Receptores de Progesterona/genética , Receptores de Progesterona/metabolismo , Útero/patologia
3.
Gen Comp Endocrinol ; 211: 39-51, 2015 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-25448252

RESUMO

Metopograpsus messor, a brachyuran crab inhabiting the estuaries of North Kerala (India), is a prolific breeder releasing approximately 14-16 broods a year. The present paper reports the sequence information on the DNA binding domain (C domain, DBD), linker (D domain) and ligand binding domain (E domain, LBD) of M. messor ecdysteroid receptor (MmEcR) gene, the first grapsid brachyuran crab EcR examined. We have also measured MmEcR transcript levels in the ovary and the hepatopancreas throughout the annual cycle, with special reference to seasons of molt and reproduction. MmEcR expression in both the tissues is found to be at its peak (P<0.05) in late premolt crabs (January/May, molt/reproduction season); the expression levels are lowest (P<0.05) during June/July, when the females would neither molt nor reproduce (season for molt/reproduction repose). Intermediate levels of expression were found during the breeding season (August/December). Interestingly, this pattern of gene expression is in concordance with the fluctuating ecdysteroid levels of the hemolymph and Y organ secretory activity. The significant levels of fluctuation in the ovarian expression of MmEcR strongly suggest the ovary as a potential target for ecdysteroid action. A season-wise comparison of the gene expression reveals that ovarian MmEcR transcript levels are higher in breeding crabs (August/December) than the non-breeding animals (June/July), implicating a possible ecdysteroid role in reproduction in M. messor.


Assuntos
Braquiúros/genética , Braquiúros/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Muda/genética , Receptores de Esteroides/genética , Estações do Ano , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , Ecdisteroides/metabolismo , Feminino , Humanos , Ligantes , Modelos Moleculares , Dados de Sequência Molecular , Filogenia , Estrutura Terciária de Proteína , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Esteroides/química , Receptores de Esteroides/metabolismo , Reprodução/genética , Alinhamento de Sequência
4.
Indian J Pathol Microbiol ; 52(3): 374-6, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19679965

RESUMO

A two-month-old female child presented with discrete skin-colored papules on the forehead and scalp. She was earlier diagnosed to have neuroblastoma of the adrenal gland which had metastasized to the liver. Histological sections of the skin lesion showed a nodule composed of sheets of cells with abundant eosinophilic cytoplasm and an occasional grooving of the nucleus. These cells were CD 68 positive. Eosinophilic abscesses were seen in between the neoplastic cells.


Assuntos
Doenças do Recém-Nascido/diagnóstico , Doenças do Recém-Nascido/patologia , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/secundário , Neuroblastoma/diagnóstico , Neuroblastoma/patologia , Neoplasias das Glândulas Suprarrenais/patologia , Glândulas Suprarrenais/patologia , Antígenos CD/análise , Antígenos de Diferenciação Mielomonocítica/análise , Feminino , Histocitoquímica , Humanos , Lactente , Recém-Nascido , Neoplasias Hepáticas/patologia , Neuroblastoma/complicações , Gravidez , Neoplasias Cutâneas/diagnóstico , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/secundário , Adulto Jovem
5.
Can J Microbiol ; 53(2): 196-206, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17496967

RESUMO

Plant extracts and antifungal microorganisms were tested singly and in combination for biocontrol of sugarcane red rot disease (Colletotrichum falcatum) using two sugarcane (Saccharum officinarum L.) cultivars, CoC671 and CoC92061, in pot and field experiments. Leaf extracts of Abrus precatorius and Bassia latifolia and the rhizome extract of Curcuma longa reduced Colletotrichum falcatum mycelial growth by 80%, 58%, and 57%, respectively. Although sugarcane- planting materials (setts) treated individually with either Pseudomonas fluorescens Md1 or A. precatorius in pot experiments had the lowest incidences of red rot, 20.1% and 24.2%, respectively, none of the plant extracts were effective in the field. In contrast, when the two varieties were tested separately in two field locations, the setts treated with A. precatorius in combination with a spray or soil application of P. fluorescens Md1 had the lowest incidence of red rot in both locations, e.g., 3.1% and 3.4% incidence for CoC92061 in one location, and had a similar response to the chemical control. The results suggest the applicability of plant-based extracts for the suppression of sugarcane red rot disease in the field as an environment-friendly tool in combination with antagonists.


Assuntos
Bacillus/fisiologia , Colletotrichum/crescimento & desenvolvimento , Controle Biológico de Vetores/métodos , Doenças das Plantas , Extratos Vegetais/farmacologia , Pseudomonas/fisiologia , Saccharum/microbiologia , Microbiologia do Solo , Trichoderma/fisiologia , Colletotrichum/efeitos dos fármacos
7.
Microbiol Res ; 160(3): 291-8, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16035241

RESUMO

Rhizoctonia solani isolates varying in their virulence were tested for their ability to produce oxalic acid (OA) in vitro. The results indicated that the virulent isolates produced more OA than the less virulent isolates. In order to isolate OA-detoxifying strains of Pseudomonas fluorescens, rhizosphere soil of rice was drenched with 100 mM OA and fluorescent pseudomonads were isolated from the OA-amended soil by using King's medium B. These isolates were tested for their antagonistic effect towards growth of R. solani in vitro. Among them P. fluorescens PfMDU2 was the most effective in inhibiting the mycelial growth of R. solani. P. fluorescens PfMDU2 was capable of detoxifying OA and several proteins were detected in the culture filtrate of PfMDU2 when it was grown in medium containing OA. To investigate whether the gene(s) involved in OA-detoxification resides on the plasmids in P. fluorescens PfMDU2, a plasmid-deficient strain of P. fluorescens was generated by plasmid curing. The plasmid-deficient strain (PfMDU2P-) failed to grow in medium containing OA and did not inhibit the growth of R. solani. Both PfMDU2 and PfMDU2P- were tested for their efficacy in controlling sheath blight of rice under greenhouse conditions. Seed treatment followed by soil application of rice with P. fluorescens strain, PfMDU2, reduced the severity of sheath blight by 75% compared with the control, whereas PfMDU2P- failed to control sheath blight disease.


Assuntos
Antibiose , Oryza/microbiologia , Ácido Oxálico/metabolismo , Controle Biológico de Vetores , Pseudomonas fluorescens/metabolismo , Rhizoctonia/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Plasmídeos , Pseudomonas fluorescens/genética , Pseudomonas fluorescens/crescimento & desenvolvimento , Rhizoctonia/patogenicidade
8.
J Mol Endocrinol ; 34(2): 447-57, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15821109

RESUMO

Internalization of the ligand/receptor complexes is a consequence of the activation of the gonadotropin receptors. Since the recycling or degradation of the internalized receptors results in the maintenance or loss of cell surface receptors respectively and this contributes to the loss of responsiveness, we hypothesized that the fate of the internalized receptors could be an important component of desensitization. We examined this hypothesis using the wild-type and mutants of the human LH (hLHR) receptors and follitropin receptors expressed in MA-10 and KK-1 cells respectively. The receptor mutants were chosen because they are routed mostly to a lysosomal degradation pathway whereas the wild-type receptors are recycled back to the surface. We have shown that agonist stimulation of cells expressing the mutant receptors results in a more pronounced loss of cell surface receptors and agonist responses than stimulation of cells expressing the wild-type receptors. We concluded that receptor recycling promotes the maintenance of cell surface receptors and preserves hormonal responsiveness. This property of the hLHR is likely to be physiologically important because there at least two hLHR-expressing tissues in pregnant women, the maternal corpus luteum and the fetal Leydig cells, where a loss of hormonal responsiveness induced by the elevated levels of human chorionic gonadotropin that occur during pregnancy is not desirable.


Assuntos
Endocitose/fisiologia , Hormônio Foliculoestimulante/metabolismo , Hormônio Luteinizante/metabolismo , Receptores do FSH/metabolismo , Receptores do LH/metabolismo , Animais , Linhagem Celular , Gonadotropina Coriônica/metabolismo , AMP Cíclico/metabolismo , Regulação para Baixo , Feminino , Hormônio Foliculoestimulante/genética , Humanos , Hormônio Luteinizante/genética , Gravidez , Progesterona/metabolismo , Ensaio Radioligante , Receptores do FSH/genética , Receptores do LH/genética
9.
Indian J Biochem Biophys ; 42(6): 371-7, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16955738

RESUMO

The Pseudomonas fluorescens isolate Pfl was found to inhibit the growth of pathogen Alternaria palandui, in vitro. In the present study, foliar application of a talc-based formulation of Pfl significantly reduced the incidence of leaf blight of onion, caused by A. palandui. Induction of defense-related proteins viz., chitinase, beta-1,3 glucanase, peroxidase (PO) and polyphenol oxidase (PPO) by application of Pfl, was studied against A. palandui infection in resistant (IHR 56) and susceptible (MDUI) onion cultivars. Chitinase in both cultivars, with or without challenge-inoculation of A. palandui revealed changes in the isoform pattern. The Native-PAGE of PO showed induction of PO2 isoform in both the cultivars, in response to inoculation of pathogen. Isoform analysis of PPO also exhibited induction in the Pfl-treated plants challenged with pathogen. Similarly, the activity of beta-1,3-glucanase was greatly induced in Pfl-treated plants, challenged with pathogen as compared to controls. Thus, the P. fluorescens-treated plants showed significant increase in the levels of the defense enzymes, in comparison to the plants challenged with the pathogen.


Assuntos
Imunidade Celular , Cebolas , Doenças das Plantas , Pseudomonas fluorescens/patogenicidade , Catecol Oxidase/metabolismo , Quitinases/metabolismo , Glucana 1,3-beta-Glucosidase/metabolismo , Interações Hospedeiro-Parasita , Cebolas/enzimologia , Cebolas/microbiologia , Peroxidase/metabolismo , Doenças das Plantas/microbiologia , Folhas de Planta/enzimologia , Pseudomonas fluorescens/crescimento & desenvolvimento , Pseudomonas fluorescens/imunologia , Virulência
10.
Microbiol Res ; 159(1): 73-81, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15160609

RESUMO

Fourteen strains of Pseudomonas fluorescens isolated from rhizosphere soil of rice were tested for their antagonistic effect towards Rhizoctonia solani, the rice sheath blight fungus. Among them, PfMDU2 was the most effective in inhibiting mycelial growth of R. solani in vitro. Production of chitinase, beta-1,3-glucanase, siderophores, salicylic acid (SA) and hydrogen cyanide (HCN) by P. fluorescens strains was evaluated. The highest beta-1,3-glucanase activity, siderophore production, SA production and HCN production were recorded with PfMDU2. A significant relationship between the antagonistic potential of P. fluorescens against R. solani and its level of beta-1,3-glucanase, SA and HCN was observed.


Assuntos
Antibiose , Enzimas/farmacologia , Pseudomonas fluorescens/metabolismo , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/crescimento & desenvolvimento , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Quitinases/metabolismo , Quitinases/farmacologia , Enzimas/metabolismo , Glucana 1,3-beta-Glucosidase/metabolismo , Glucana 1,3-beta-Glucosidase/farmacologia , Cianeto de Hidrogênio/metabolismo , Cianeto de Hidrogênio/farmacologia , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Controle Biológico de Vetores/métodos , Pseudomonas fluorescens/enzimologia , Pseudomonas fluorescens/isolamento & purificação , Ácido Salicílico/metabolismo , Ácido Salicílico/farmacologia , Sideróforos/análise , Sideróforos/metabolismo , Sideróforos/farmacologia , Microbiologia do Solo
11.
J Assoc Physicians India ; 48(4): 439-40, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11273185

RESUMO

We report a family of two brothers with familial infantile myaesthenia which is an autosomal recessive congenital myaesthenic syndrome. It is a presynaptic neuro muscular junction disorder, responsive to treatment and has got good prognosis.


Assuntos
Síndromes Miastênicas Congênitas/genética , Adolescente , Criança , Inibidores da Colinesterase/uso terapêutico , Humanos , Masculino , Síndromes Miastênicas Congênitas/tratamento farmacológico , Síndromes Miastênicas Congênitas/fisiopatologia
12.
J Assoc Physicians India ; 46(9): 824-6, 1998 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11229259

RESUMO

We report a case of crossed aphasia following a vascular insult of the right hemisphere in a middle aged dextral man with subsequent evolution to pure word deafness. Development of pure word deafness during recovery from crossed Wernickes aphasia is an extremely rare clinical entity. Probably this is the first Indian report of this entity.


Assuntos
Afasia/complicações , Surdez/etiologia , Infarto Cerebral/complicações , Infarto Cerebral/diagnóstico , Evolução Fatal , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade
13.
Mol Cell Biol ; 16(7): 3338-49, 1996 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8668149

RESUMO

Several mechanisms are employed by members of transcription factor families to achieve sequence-specific DNA recognition. In this study, we have investigated how members of the ETS-domain transcription factor family achieve such specificity. We have used the ternary complex factor (TCF) subfamily as an example. ERK2 mitogen-activated protein kinase stimulates serum response factor-dependent and autonomous DNA binding by the TCFs Elk-1 and SAP-la. Phosphorylated Elk-1 and SAP-la exhibit specificities of DNA binding similar to those of their isolated ETS domains. The ETS domains of Elk-1 and SAP-la and SAP-2 exhibit related but distinct DNA-binding specificities. A single residue, D-69 (Elk-1) or V-68 (SAP-1), has been identified as the critical determinant for the differential binding specificities of Elk-1 and SAP-1a, and an additional residue, D-38 (Elk-1) or Q-37 (SAP-1), further modulates their DNA binding. Creation of mutations D38Q and D69V is sufficient to confer SAP-la DNA-binding specificity upon Elk-1 and thereby allow it to bind to a greater spectrum of sites. Molecular modelling indicates that these two residues (D-38 and D-69) are located away from the DNA-binding interface of Elk-1. Our data suggest a mechanism in which these residues modulate DNA binding by influencing the interaction of other residues with DNA.


Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , DNA/química , DNA/metabolismo , Proteínas Proto-Oncogênicas/química , Proteínas Proto-Oncogênicas/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Sítios de Ligação , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Clonagem Molecular , Sequência Consenso , Escherichia coli , Proteína Quinase 1 Ativada por Mitógeno , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Conformação de Ácido Nucleico , Oligodesoxirribonucleotídeos , Plasmídeos , Reação em Cadeia da Polimerase , Estrutura Secundária de Proteína , Proteínas Tirosina Quinases/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Mapeamento por Restrição , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Proteínas Elk-1 do Domínio ets , Proteínas Elk-4 do Domínio ets
14.
J Biomol Struct Dyn ; 13(4): 627-39, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8906883

RESUMO

In order to investigate the environmental conditions of amino acid residues in protein molecules, four kinds of packing studies (atomic, geometric, hydrophobic and hydration) were formulated and tested on two proteins; bovine pancreatic trypsin inhibitor (BPTI) and bovine pancreatic ribonuclease S (RNase S). The inter-relationship of these packings on the fluctuations of amino acid residues was analysed by comparing the packing results with the dynamical studies, such as the root-mean-square-deviation values of atomic displacements obtained from the trajectories of molecular dynamics simulation, temperature factor information from crystal structures and residue fluctuations in proteins from continuum model. These analyses yield information about the most fluctuating and most stabilizing residue sites. Comparison of the results obtained by these methods indicate a good agreement, specifying an inverse correlation between the residue packing and fluctuations. This kind of study is helpful in identifying the specific residue sites such as nucleation, receptor binding and antigenic determining sites which in a way indirectly correlates with the functional residues in protein molecules.


Assuntos
Aminoácidos , Aprotinina/análogos & derivados , Computação Matemática , Modelos Moleculares , Peptídeos Cíclicos/química , Ribonuclease Pancreático/química , Ribonucleases/química , Animais , Aprotinina/química , Bovinos , Simulação por Computador , Conformação Proteica , Dobramento de Proteína
15.
Int J Pept Protein Res ; 46(1): 88-96, 1995 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-7558602

RESUMO

The solution conformation of a synthetic cyclic decapeptide [with sequence mimicking the third disulfide loop of rat transforming growth factor-alpha (rTGF-alpha)] in deuterated dimethyl sulfoxide was studied by 2D NMR. The determination of solution structures was based on NOE interproton distances, using a combination of distance geometry and simulated annealing protocols. The convergence of the selected structures was evident from the small atomic pairwise root-mean-square deviation values among them. Good agreement was noted between the experimental and simulated NOESY spectra, thereby reflecting the accuracy of the calculated solution structures. Analysis of the structures indicates that the residues Tyr5 and Arg9 exhibit similar side chain orientation as that in the corresponding disulfide loop of human transforming growth factor-alpha.


Assuntos
Fragmentos de Peptídeos/química , Peptídeos Cíclicos/química , Fator de Crescimento Transformador alfa/química , Sequência de Aminoácidos , Animais , Arginina/química , Dicroísmo Circular , Gráficos por Computador , Dissulfetos/química , Humanos , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Fragmentos de Peptídeos/síntese química , Peptídeos Cíclicos/síntese química , Conformação Proteica , Ratos , Tirosina/química
16.
Biochim Biophys Acta ; 1201(2): 149-56, 1994 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-7947926

RESUMO

The solution conformation of griseoviridin, a broad spectrum antibiotic, has been determined by 1H-NMR in deuterated dimethylsulfoxide. The structural determination is based on experimental data of NOE constraints Five structures were obtained from restrained molecular dynamics calculations, by imposing (the condition for) a minimum violation of distance constraints. These structures satisfy well the experimental restraints, with small values of NOE violation and total energies. On comparison with its crystal structure, a good agreement is noted with a backbone root-mean-square deviation value of 0.084 nm. However, a small variation between the structures is observed at the aminodecanoic acid part of the molecule.


Assuntos
Antibacterianos/química , Peptídeos , Dimetil Sulfóxido , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Soluções
17.
J Biol Chem ; 269(38): 23500-8, 1994 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-8089116

RESUMO

The three-dimensional structure in solution of cardiotoxin II, a membrane toxin from the venom of Taiwan cobra, Naja naja atra, was determined using 1H nuclear magnetic resonance spectroscopy and molecular modeling based on the hybrid distance geometry/dynamic simulated annealing technique. A complete sequence-specific proton assignment was obtained, and the secondary structures of the protein were determined from information on nuclear Overhauser effect connectivities, coupling constants, and hydrogen exchange were confirmed using the main-chain-directed strategy. Twelve simulated annealing structures found to be within a single family were selected based on the condition of distance constraint violation less than 0.02 nm and the dihedral angle violation less than 4 degrees. The average atomic root mean square deviation between the selected structures and their geometric average are 0.079 nm for the backbone atoms and 0.137 nm for all heavy atoms; they are 0.044 nm and 0.117 nm, respectively, when considering the secondary structural residues only. The molecule adopts a compact structure consisting of three major loops emerging from a globular head. These loops contain five strands to form double- and a triple-stranded antiparallel beta sheets. Comparisons are made between this structure and those of its homologous cardiotoxins in order to derive further information on their structural variations.


Assuntos
Proteínas Cardiotóxicas de Elapídeos/química , Sequência de Aminoácidos , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Dados de Sequência Molecular , Movimento (Física) , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Soluções
18.
J Antibiot (Tokyo) ; 47(8): 922-31, 1994 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7928680

RESUMO

Studies on the solution conformation of the cyclic depsipeptide antibiotic enopeptin A have been carried out using 2D NMR and molecular modelling techniques. The proton resonances of the antibiotic in DMSO-d6 have been assigned by the use of TOCSY and ROESY experiments. The interproton distance information obtained from the ROESY experiments have been used as the basis for elucidating the probable structures in solution. The restrained molecular dynamics technique was applied to calculate the structures in solution, and six resultant structures with fewer distance constraint violations were obtained that satisfy the experimental restraints very well. The conformation of the cyclic moiety of the molecules is well defined whereas the aliphatic chain segment is disordered.


Assuntos
Peptídeos Cíclicos/química , Sequência de Aminoácidos , Deutério , Dimetil Sulfóxido , Espectroscopia de Ressonância Magnética/métodos , Modelos Químicos , Conformação Molecular , Dados de Sequência Molecular , Conformação Proteica , Soluções , Análise Espectral/métodos , Termodinâmica
19.
Int J Pept Protein Res ; 43(4): 393-401, 1994 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8045686

RESUMO

The conformation of viroisin, the monocyclic toxic heptapeptide of the virotoxin family from mushroom Amanita virosa, was analysed using two-dimensional nuclear magnetic resonance spectroscopy and restrained molecular dynamics simulations. All proton signals were completely assigned, and interproton distances were determined using data from rotating-frame nuclear Overhauser enhancement. The backbone dihedral angles were deduced from measurements of coupling constants. The temperature dependence of the amide proton chemical shifts provided information about hydrogen bonding. Six probable solution conformations of viroisin were derived from the use of distance geometry and restrained molecular dynamics based on a set of distance constraints obtained from experimental data. The results of the structural analysis indicate that viroisin has a well ordered conformation in solution. In all these conformations the functional groups essential for toxicity orient themselves in the same direction so as to bind to the target proteins. This feature is consistent with previous results about the formation of a hydrophobic pocket on one side of the molecule.


Assuntos
Amanitinas/química , Espectroscopia de Ressonância Magnética , Peptídeos Cíclicos/química , Sequência de Aminoácidos , Fenômenos Químicos , Físico-Química , Ligação de Hidrogênio , Dados de Sequência Molecular , Estrutura Molecular , Conformação Proteica , Soluções , Temperatura , Termodinâmica
20.
Biochim Biophys Acta ; 1199(2): 115-22, 1994 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-8123660

RESUMO

We determined the structure in solution of the vaso-constrictor hormone urotensin II (dodecapeptide) using nuclear magnetic resonance spectroscopy. Complete assignment of all proton resonances has been achieved and the structural information has been obtained from the interproton distance measurements derived from the nuclear Overhauser enhancement data. A combination of distance geometry and dynamical simulated annealing techniques was used to calculate the structure in solution. Nine resultant structures with fewer distance constraint violations were selected that satisfy the experimental restraints very well. The conformation of the molecule in the cyclic hexapeptide segment (core region) is well-defined whereas the N-terminal segment is disordered. This result correlates very well with the earlier predictions about the biologically active and inactive roles played by the core and the N-terminal segment respectively.


Assuntos
Urotensinas/química , Sequência de Aminoácidos , Simulação por Computador , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Conformação Proteica , Soluções
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