Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Molecules ; 26(17)2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34500777

RESUMO

Human neutrophil elastase (HNE) is a uniquely destructive serine protease with the ability to unleash a wave of proteolytic activity by destroying the inhibitors of other proteases. Although this phenomenon forms an important part of the innate immune response to invading pathogens, it is responsible for the collateral host tissue damage observed in chronic conditions such as chronic obstructive pulmonary disease (COPD), and in more acute disorders such as the lung injuries associated with COVID-19 infection. Previously, a combinatorially selected activity-based probe revealed an unexpected substrate preference for oxidised methionine, which suggests a link to oxidative pathogen clearance by neutrophils. Here we use oxidised model substrates and inhibitors to confirm this observation and to show that neutrophil elastase is specifically selective for the di-oxygenated methionine sulfone rather than the mono-oxygenated methionine sulfoxide. We also posit a critical role for ordered solvent in the mechanism of HNE discrimination between the two oxidised forms methionine residue. Preference for the sulfone form of oxidised methionine is especially significant. While both host and pathogens have the ability to reduce methionine sulfoxide back to methionine, a biological pathway to reduce methionine sulfone is not known. Taken together, these data suggest that the oxidative activity of neutrophils may create rapidly cleaved elastase "super substrates" that directly damage tissue, while initiating a cycle of neutrophil oxidation that increases elastase tissue damage and further neutrophil recruitment.


Assuntos
Imunidade Inata , Elastase de Leucócito/metabolismo , Metionina/análogos & derivados , Neutrófilos/imunologia , Biocatálise , COVID-19/imunologia , COVID-19/patologia , COVID-19/virologia , Domínio Catalítico/genética , Ensaios Enzimáticos , Interações Hospedeiro-Patógeno/imunologia , Humanos , Elastase de Leucócito/antagonistas & inibidores , Elastase de Leucócito/genética , Pulmão/imunologia , Pulmão/patologia , Pulmão/virologia , Metionina/metabolismo , Simulação de Dinâmica Molecular , Infiltração de Neutrófilos , Neutrófilos/enzimologia , Oxirredução/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Doença Pulmonar Obstrutiva Crônica/imunologia , Doença Pulmonar Obstrutiva Crônica/patologia , SARS-CoV-2/imunologia , Especificidade por Substrato/imunologia
2.
Mar Drugs ; 17(12)2019 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-31842369

RESUMO

Serine proteases play pivotal roles in normal physiology and a spectrum of patho-physiological processes. Accordingly, there is considerable interest in the discovery and design of potent serine protease inhibitors for therapeutic applications. This led to concerted efforts to discover versatile and robust molecular scaffolds for inhibitor design. This investigation is a bioprospecting study that aims to isolate and identify protease inhibitors from the cnidarian Actinia tenebrosa. The study isolated two Kunitz-type protease inhibitors with very similar sequences but quite divergent inhibitory potencies when assayed against bovine trypsin, chymostrypsin, and a selection of human sequence-related peptidases. Homology modeling and molecular dynamics simulations of these inhibitors in complex with their targets were carried out and, collectively, these methodologies enabled the definition of a versatile scaffold for inhibitor design. Thermal denaturation studies showed that the inhibitors were remarkably robust. To gain a fine-grained map of the residues responsible for this stability, we conducted in silico alanine scanning and quantified individual residue contributions to the inhibitor's stability. Sequences of these inhibitors were then used to search for Kunitz homologs in an A. tenebrosa transcriptome library, resulting in the discovery of a further 14 related sequences. Consensus analysis of these variants identified a rich molecular diversity of Kunitz domains and expanded the palette of potential residue substitutions for rational inhibitor design using this domain.


Assuntos
Cnidários/classificação , Serina Proteases/efeitos dos fármacos , Inibidores de Serino Proteinase/farmacologia , Animais , Bovinos , Quimotripsina/antagonistas & inibidores , Quimotripsina/metabolismo , Simulação por Computador , Humanos , Simulação de Dinâmica Molecular , Serina Proteases/metabolismo , Inibidores de Serino Proteinase/isolamento & purificação , Tripsina/efeitos dos fármacos , Tripsina/metabolismo , Inibidores da Tripsina/isolamento & purificação , Inibidores da Tripsina/farmacologia
3.
J Med Chem ; 62(7): 3696-3706, 2019 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-30888159

RESUMO

Sunflower trypsin inhibitor-1 (SFTI-1) is a 14-amino acid cyclic peptide that shares an inhibitory loop with a sequence and structure similar to a larger family of serine protease inhibitors, the Bowman-Birk inhibitors. Here, we focus on the P5' residue in the Bowman-Birk inhibitory loop and produce a library of SFTI variants to characterize the P5' specificity of 11 different proteases. We identify seven amino acids that are generally preferred by these enzymes and also correlate with P5' sequence diversity in naturally occurring Bowman-Birk inhibitors. Additionally, we show that several enzymes have divergent specificities that can be harnessed in engineering studies. By optimizing the P5' residue, we improve the potency or selectivity of existing inhibitors for kallikrein-related peptidase 5 and show that a variant with substitutions at 7 of the scaffold's 14 residues retains a similar structure to SFTI-1. These findings provide new insights into P5' specificity requirements for the Bowman-Birk inhibitory loop.


Assuntos
Aminoácidos/metabolismo , Serina Proteases/metabolismo , Inibidor da Tripsina de Soja de Bowman-Birk/farmacologia , Quimotripsina/metabolismo , Fator XIIa/metabolismo , Humanos , Serina Endopeptidases/metabolismo , Especificidade por Substrato , Trombina/metabolismo , Tripsina/metabolismo
4.
PLoS One ; 14(1): e0210842, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30668585

RESUMO

Engagement of an extended ß-sheet is a common substrate/inhibitor interaction at the active site of serine proteases and is an important feature of Laskowski mechanism inhibitors that present a substrate-like loop to a target protease. This loop is cleaved but subsequently relegated forming a stable inhibitor/protease complex. Laskowski inhibitors are ubiquitous in nature and are used extensively in serine protease inhibitor design. However, most studies concentrate on introducing new sidechain interactions rather than the direct contributions of the substrate-like ß-sheet to enzyme inhibition. Here we report the crystal structure of an simplified ß-sheet inhibitory motif within the Sunflower Trypsin Inhibitor (SFTI) in complex with trypsin. We show that the intramolecular hydrogen bond network of this SFTI variant (SFTI-TCTR) engages the inhibitor sidechains that would normally interact with a target protease, giving mainchain interactions a more prominent role in complex formation. Despite having reduced sidechain interactions, this SFTI variant is remarkably potent and inhibits a diverse range of serine proteases. Crystal structural analysis and molecular modelling of SFTI-TCTR complexes again indicates an interface dominated by ß-sheet interactions, highlighting the importance of this motif and the adaptability of SFTI as a scaffold for inhibitor design.


Assuntos
Inibidores de Serino Proteinase/química , Inibidores de Serino Proteinase/farmacologia , Tripsina/química , Motivos de Aminoácidos , Animais , Bovinos , Cristalografia por Raios X , Helianthus/química , Ligação de Hidrogênio , Modelos Moleculares , Simulação de Dinâmica Molecular , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologia , Proteínas de Plantas/química , Proteínas de Plantas/farmacologia , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Eletricidade Estática , Inibidores da Tripsina/química , Inibidores da Tripsina/farmacologia
5.
Biomed Res Int ; 2018: 1948407, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29850486

RESUMO

Nitrogen oxide (NO x ) is produced during combustion at high temperature, which is a major constituent of air pollutants. Recent studies suggested inconsistent results on the association between NO x exposure and cardiovascular-related malformations. We aimed to assess aforementioned association in pregnant women in the first trimester and cardiovascular-related malformations of infants. A systematic literature review identified studies for observational studies about NO x exposure and cardiovascular-related malformation in PubMed. Random-effect models were used to estimate summary odds ratio (SOR) and 95% confidence intervals (CIs) for aforementioned association. Finally, nine studies met the inclusion criteria. Overall, the SOR of cardiovascular-related malformation per 10 ppb increment in NO x and NO2 concentration was 1.01 (95% CI: 0.98-1.04; I2 = 38.6%, P = 0.09) and 0.99 (95% CI: 0.95-1.04; I2 = 37.8%, P = 0.13), respectively. Stratifying by study design, geographic locations, and confounded adjustments, the majority of strata showed negative results, which were consistent with the main findings. However, we found that exposure to NO x and NO2 in the first trimester increased the risk of coarctation of the aorta (COA) malformation by 13% and 19%, respectively. Our study provided limited evidence regarding the association between NO x exposure in the first trimester and cardiovascular-related malformations in infants.


Assuntos
Anormalidades Cardiovasculares/etiologia , Exposição Materna/efeitos adversos , Óxidos de Nitrogênio/efeitos adversos , Estudos Observacionais como Assunto , Primeiro Trimestre da Gravidez/fisiologia , Feminino , Humanos , Gravidez , Fatores de Risco
6.
Oncotarget ; 8(39): 65969-65982, 2017 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-29029486

RESUMO

Epidermal growth factor (EGF) and EGF receptor (EGFR) play prominent roles in the metastasis of glioblastoma (GBM). However, the molecular mechanisms for the function of EGF and EGFR in GBM metastasis have not been elucidated. Herein, we demonstrate that coactivation of EGF and EGFR drives tumor metastasis in a matrix metalloproteinase-9 (MMP-9)-dependent manner. Expression levels of EGF, EGFR, and MMP-9 were substantially upregulated in the GBM and edema zones of patients, compared with those of paired unaffected participants. Secretion of EGF and MMP-9 was reduced in the cerebrospinal fluid (CSF) after removing GBM for 2 weeks by operation. To the mechanism, MMP-9 was upregulated by activating EGF and EGFR via PI3K/AKT- and ERK1/2-dependent pathways. Moreover, signal transducer and activator of transcription (STAT) 3 and STAT5 mediated the activation of NF-κB by PI3K/AKT and ERK1/2 pathways. This resulted in transactivation of MMP-9 in GBM. Finally, MMP-9 induction facilitated abnormal proliferation, migration, and invasion of cells, which contributed to GBM metastasis.

7.
Healthc Q ; 16(1): 39-46, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24863306

RESUMO

The Institute of Medicine (IOM) framework has been used frequently to assess and monitor quality in secondary and tertiary care, but not in primary care. This article describes and proposes a conceptual framework for categorizing primary care indicators that align with the IOM's six aims for quality in healthcare performance (Safe, Effective, Patient-Centred, Timely, Efficient and Equitable.) Using an iterative process, the authors developed and compared a primary care framework for categorizing indicators in the Quality in Family Practice Book of Tools (QBT) with the IOM aims and other local healthcare systems frameworks (Integrated and Continuous, Appropriate Practice Resources). They also compared, cross-matched and analyzed their QBT categories and indicators with other international primary care assessment tools. And they compared the QBT titles and descriptions of groups of indicators with those published in the international tools.


Assuntos
Atenção Primária à Saúde/normas , Garantia da Qualidade dos Cuidados de Saúde , Indicadores de Qualidade em Assistência à Saúde , National Academies of Science, Engineering, and Medicine, U.S., Health and Medicine Division , Ontário , Estados Unidos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...