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Avians differ from mammals, especially in brain architecture and metabolism. Taurine, an amino acid basic to metabolism and bioenergetics, has been shown to have remarkable effects on metabolic syndrome and ameliorating oxidative stress reactions across species. However, less is known regarding these metabolic relationships in the avian model. The present study serves as a preliminary report that examined how taurine might affect avian metabolism in an aged model system. Two groups of pigeons (Columba livia) of mixed sex, a control group and a group that received 48 months of taurine supplementation (0.05% w/v) in their drinking water, were compared by using blood panels drawn from their basilic vein by a licensed veterinarian. From the blood panel data, taurine treatment generated higher levels of three ATP-related enzymes: glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH), and creatine kinase (CK). In this preliminary study, the role that taurine treatment might play in the adult aged pigeon's metabolism on conserved traits such as augmenting insulin production as well as non-conserved traits maintaining high levels of ATP-related enzymes was examined. It was found that taurine treatment influenced the avian glucose metabolism similar to mammals but differentially effected avian ATP-related enzymes in a unique way (i.e., â¼×2 increase in CK and LDH with a nearly ×4 increase in GLDH). Notably, long-term supplementation with taurine had no negative effect on parameters of lipid and protein metabolism nor liver enzymes. The preliminary study suggests that avians may serve as a unique model system for investigating taurine metabolism across aging with long-term health implications (e.g., hyperinsulinemia). However, the suitability of using the model would require researchers to tightly control for age, sex, dietary intake, and exercise conditions as laboratory-housed avian present with very different metabolic panels than free-flight avians, and their metabolic profile may not correlate one-to-one with mammalian data.
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Suplementos Nutricionais , Taurina , Animais , Taurina/farmacologia , Columbidae/metabolismo , Glucose/metabolismo , Trifosfato de Adenosina , Mamíferos/metabolismoAssuntos
Doença Celíaca , Glucocorticoides , Humanos , Glucocorticoides/administração & dosagem , Glucocorticoides/uso terapêutico , Glucocorticoides/efeitos adversos , Masculino , Feminino , Pessoa de Meia-Idade , Adulto , Administração Tópica , Resultado do Tratamento , Idoso , Estudos RetrospectivosRESUMO
OBJECTIVES: Despite significant investment in social prescribing in England over the last decade, we still do not know if it works, or how models of social prescribing fit within wider health and care policy and practice. This study explores current service delivery structures and assesses the feasibility of a national evaluation of the link worker model. METHODS: Semi-structured interviews were conducted between May and September 2020, with 25 key informants from across social prescribing services in England. Participants included link workers, voluntary, community and social enterprise staff, and those involved in policy and decision-making for social prescribing services. Interview and workshop transcripts were analysed thematically, adopting a framework approach. RESULTS: We found differences in how services are provided, including by individual link workers, and between organisations and regions. Standards, referral pathways, reporting, and monitoring structures differ or are lacking in voluntary services as compared to clinical services. People can self-refer to a link worker or be referred by a third party, but the lack of standardised processes generated confusion in both public and professional perceptions of the link worker model. We identified challenges in determining the appropriate outcomes and outcome measures needed to assess the impact of the link worker model. CONCLUSIONS: The current varied service delivery structures in England poses major challenges for a national impact evaluation. Any future rigorous evaluation needs to be underpinned with national standardised outcomes and process measures which promote uniform data collection.
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Seguridade Social , Serviço Social , Humanos , Pesquisa Qualitativa , Estudos de Viabilidade , InglaterraRESUMO
Initiatives designed to reduce the disease burden and improve the health of the US population that focus on increasing access to health care have been disappointing. Progress requires multifaceted change. We must first acknowledge that the healthcare system is focused on reversing or modifying disease, not enhancing health. Our conceptualization of the development of ill health and disease must also change. Scientific advances are clarifying the complex interactions among the development of ill health and disease and an individual's behaviors, their microbiota, and their physical, social, and emotional environments. A person's genetic makeup predisposes them to a wide array of disease conditions but is rarely deterministic in and of itself. Factors extrinsic to the individual, including the social determinants of health, play a major role in disease development, often decades later. The complexity of health and disease requires a "team" accountable for the health of our populations, and these teams must be expanded beyond the medical professions. Governmental officials, architects, business leaders, civic organizations, social and neighborhood groups are among the key stakeholders on the health side of the equation. If and when disease does become manifest, then the care part of the healthcare system assumes the larger role. This has major implications for the education of our clinically focused health science students, but also of professional disciplines previously deemed peripheral to health. Simply redoubling our efforts and focusing on our current healthcare system is insufficient to make progress in the health of the populace. One example of a multipronged approach in Allentown, PA is explored in depth.
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OBJECTIVES: The aim of this systematic overview of reviews was to synthesise available evidence on inequalities in infectious disease based on three dimensions of inequalities; inclusion health groups, protected characteristics and socioeconomic inequalities. METHODS: We searched MEDLINE, Embase, Web of Science and OpenGrey databases in November 2021. We included reviews published from the year 2000 which examined inequalities in the incidence, prevalence or consequences of infectious diseases based on the dimensions of interest. Our search focused on tuberculosis, HIV, sexually transmitted infections, hepatitis C, vaccination and antimicrobial resistance. However, we also included eligible reviews of any other infectious diseases. We appraised the quality of reviews using the Assessment of Multiple Systematic Reviews V.2 (AMSTAR2) checklist. We conducted a narrative data synthesis. RESULTS: We included 108 reviews in our synthesis covering all the dimensions of inequalities for most of the infectious disease topics of interest, however the quality and volume of review evidence and consistency of their findings varied. The existing literature reviews provide strong evidence that people in inclusion health groups and lower socioeconomic status are consistently at higher risk of infectious diseases, antimicrobial resistance and incomplete/delayed vaccination. In the protected characteristics dimension, ethnicity, and sexual orientation are important factors contributing to inequalities across the various infectious disease topics included in this overview of reviews. CONCLUSION: We identified many reviews that provide evidence of various types of health inequalities in different infectious diseases, vaccination, and antimicrobial resistance. We also highlight areas where reviews may be lacking. The commonalities in the associations and their directions suggest it might be worth targeting interventions for some high risk-groups that may have benefits across multiple infectious disease outcomes rather than operating purely in infectious disease siloes.
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Anti-Infecciosos , Doenças Transmissíveis , Infecções Sexualmente Transmissíveis , Feminino , Humanos , Masculino , Doenças Transmissíveis/epidemiologia , Desigualdades de Saúde , Classe SocialRESUMO
Factor VIII (FVIII) plays a critical role in blood coagulation by forming the tenase complex with factor IXa and calcium ions on a membrane surface containing negatively charged phospholipids. The tenase complex activates factor X during blood coagulation. The carboxyl-terminal C2 domain of FVIII is the main membrane-binding and von Willebrand factor-binding region of the protein. Mutations of FVIII cause hemophilia A, whereas elevation of FVIII activity is a risk factor for thromboembolic diseases. The C2 domain-membrane interaction has been proposed as a target of intervention for regulation of blood coagulation. A number of molecules that interrupt FVIII or factor V (FV) binding to cell membranes have been identified through high throughput screening or structure-based design. We report crystal structures of the FVIII C2 domain under three new crystallization conditions, and a high resolution (1.15 A) crystal structure of the FVIII C2 domain bound to a small molecular inhibitor. The latter structure shows that the inhibitor binds to the surface of an exposed beta-strand of the C2 domain, Trp(2313)-His(2315). This result indicates that the Trp(2313)-His(2315) segment is an important constituent of the membrane-binding motif and provides a model to understand the molecular mechanism of the C2 domain membrane interaction.
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Membrana Celular/metabolismo , Fator VIII/química , Fator de von Willebrand/química , Coagulação Sanguínea , Cristalografia por Raios X/métodos , Histidina/química , Humanos , Modelos Moleculares , Fosfolipídeos/química , Ligação Proteica , Estrutura Terciária de Proteína , Risco , Ressonância de Plasmônio de Superfície , Tromboembolia/metabolismo , Triptofano/químicaRESUMO
BACKGROUND: Matriptase is a type II transmembrane serine protease that is found on the surfaces of epithelial cells and certain cancer cells. Matriptase has been implicated in the degradation of certain extracellular matrix components as well as the activation of various cellular proteins and proteases, including hepatocyte growth factor and urokinase. Sunflower trypsin inhibitor-1 (SFTI-1), a cyclic peptide inhibitor originally isolated from sunflower seeds, exhibits potent inhibitory activity toward matriptase. RESULTS: We have engineered and produced recombinant proteins of the matriptase protease domain, and have determined the crystal structures of the protease:SFTI-1 complex at 2.0 Å as well as the protease:benzamidine complex at 1.2 Å. These structures elaborate the structural basis of substrate selectivity of matriptase, and show that the matriptase S1 substrate specificity pocket is larger enough to allow movement of benzamidine inside the S1 pocket. Our study also reveals that SFTI-1 binds to matriptase in a way similar to its binding to trypsin despite the significantly different isoelectric points of the two proteins (5.6 vs. 8.2). CONCLUSIONS: This work helps to define the structural basis of substrate specificity of matriptase and the interactions between the inhibitor and protease. The complex structure also provides a structural template for designing new SFTI-1 derivatives with better potency and selectivity against matriptase and other proteases.
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Peptídeos Cíclicos/química , Serina Endopeptidases/química , Benzamidinas/química , Benzamidinas/metabolismo , Sítios de Ligação , Domínio Catalítico , Peptídeos Cíclicos/metabolismo , Conformação Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Serina Endopeptidases/metabolismo , Especificidade por SubstratoRESUMO
Lysophospholipids play important roles in cellular signal transduction and are implicated in many biological processes, including tumorigenesis, angiogenesis, immunity, atherosclerosis, arteriosclerosis, cancer and neuronal survival. The intracellular transport of lysophospholipids is through FA (fatty acid)-binding protein. Lysophospholipids are also found in the extracellular space. However, the transport mechanism of lysophospholipids in the extracellular space is unknown. HSA (human serum albumin) is the most abundant carrier protein in blood plasma and plays an important role in determining the absorption, distribution, metabolism and excretion of drugs. In the present study, LPE (lysophosphatidylethanolamine) was used as the ligand to analyse the interaction of lysophospholipids with HSA by fluorescence quenching and crystallography. Fluorescence measurement showed that LPE binds to HSA with a Kd (dissociation constant) of 5.6 microM. The presence of FA (myristate) decreases this binding affinity (Kd of 12.9 microM). Moreover, we determined the crystal structure of HSA in complex with both myristate and LPE and showed that LPE binds at Sudlow site I located in subdomain IIA. LPE occupies two of the three subsites in Sudlow site I, with the LPE acyl chain occupying the hydrophobic bottom of Sudlow site I and the polar head group located at Sudlow site I entrance region pointing to the solvent. This orientation of LPE in HSA suggests that HSA is capable of accommodating other lysophospholipids and phospholipids. The study provides structural information on HSA-lysophospholipid interaction and may facilitate our understanding of the transport and distribution of lysophospholipids.
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Lisofosfolipídeos/metabolismo , Albumina Sérica/química , Albumina Sérica/metabolismo , Transporte Biológico , Humanos , Lisofosfolipídeos/química , Modelos Biológicos , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
The value of mindfulness-based methods in an undergraduate field placement was investigated in relation to the acquisition of self-care and other basic clinical competencies. The participants were 22 students in an applied behavioral analysis course, which included a mindfulness-based training module, and 20 students enrolled in an experimental psychology course without mindfulness training. The Mindfulness Attention and Awareness Scale, the Freiberg Mindfulness Inventory, and the Kentucky Inventory of Mindfulness Skills were used as measurements before and after intervention. Mindfulness-trained participants kept records and were asked to share their personal experiences during supervision and an exit interview. Results demonstrated that training significantly increased mindfulness. Qualitative data indicated enhanced self-care, attention to well-being, self-awareness, active involvement acquiring skills, and empathy and compassion. The need to expand the utility of mindfulness to the realm of education and the importance of including comparison groups with other self-care modules for future studies were discussed.
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Conscientização/fisiologia , Medicina do Comportamento/educação , Competência Clínica , Meditação/métodos , Ensino/métodos , Adaptação Psicológica/fisiologia , Adulto , Estudos de Coortes , Comunicação , Empatia/fisiologia , Feminino , Humanos , Masculino , Meditação/psicologia , Psicologia Experimental/educação , Autoimagem , Estudantes , Inquéritos e Questionários , Adulto JovemRESUMO
African naked mole-rats were likely the first mammals to evolve eusociality, and thus required adaptations to conserve energy and tolerate the low oxygen (O2) and high carbon dioxide (CO2) of a densely populated fossorial nest. As hypercapnia is known to suppress neuronal activity, we studied whether naked mole-rats might demonstrate energy savings in GABAergic inhibition. Using whole-colony behavioral monitoring of captive naked mole-rats, we found a durable nest, characterized by high CO2 levels, where all colony members spent the majority of their time. Analysis of the naked mole-rat genome revealed, uniquely among mammals, a histidine point variation in the neuronal potassium-chloride cotransporter 2 (KCC2). A histidine missense substitution mutation at this locus in the human ortholog of KCC2, found previously in patients with febrile seizures and epilepsy, has been demonstrated to diminish neuronal Cl- extrusion capacity, and thus impairs GABAergic inhibition. Seizures were observed, without pharmacological intervention, in adult naked mole-rats exposed to a simulated hyperthermic surface environment, causing systemic hypocapnic alkalosis. Consistent with the diminished function of KCC2, adult naked mole-rats demonstrate a reduced efficacy of inhibition that manifests as triggering of seizures at room temperature by the GABAA receptor (GABAAR) positive allosteric modulator diazepam. These seizures are blocked in the presence of nest-like levels of CO2 and likely to be mediated through GABAAR activity, based on in vitro recordings. Thus, altered GABAergic inhibition adds to a growing list of adaptations in the naked mole-rat and provides a plausible proximate mechanism for nesting behavior, where a return to the colony nest restores GABA-mediated inhibition.
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Dióxido de Carbono/metabolismo , Suscetibilidade a Doenças/veterinária , Ratos-Toupeira , Receptores de GABA-A/metabolismo , Doenças dos Roedores/fisiopatologia , Convulsões/veterinária , Animais , Suscetibilidade a Doenças/etiologia , Suscetibilidade a Doenças/metabolismo , Feminino , Masculino , Doenças dos Roedores/genética , Convulsões/genética , Convulsões/fisiopatologiaRESUMO
The ubiquitin-conjugating enzyme E2-25K has been identified as a huntingtin (the key protein in Huntington's disease) interacting protein and has been shown to play a role in mediating the toxicity of Abeta, the principal protein involved in Alzheimer's disease pathogenesis. E2-25K is a dual-domain protein with an ubiquitin-associated (UBA) domain as well as a conserved ubiquitin-conjugating (UBC) domain which catalyzes the formation of a covalent bond between the C-terminal glycine of an ubiquitin molecule and the -amine of a lysine residue on the acceptor protein as part of the ubiquitin-proteasome pathway. The crystal structures of E2-25K M172A mutant protein at pH 6.5 and pH 8.5 were determined to 1.9 and 2.2 A resolution, respectively. Examination of the structures revealed domain-domain interactions between the UBC and UBA domains which have not previously been reported.
Assuntos
Enzimas de Conjugação de Ubiquitina/química , Cálcio/química , Cálcio/metabolismo , Cristalografia por Raios X , Modelos Moleculares , Mutação/genética , Estrutura Terciária de Proteína , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismoRESUMO
Age-related impairment of central functions is though to result from alterations of neurochemical indices of synaptic function. These neurochemical modifications involve structural proteins, neurotransmitters, neuropeptides and related receptors. Several studies demonstrated that GABA receptors, glutamic acid decarboxylase (GAD65&67), and different subpopulations of GABAergic neurons are markedly decreased in experimental animal brains during aging. Thus, the age-related decline in cognitive functions could be attributable, at least in part, to decrements in the function of the GABAergic inhibitory neurotransmitter system. In this study we show that chronic supplementation of taurine to aged mice significantly ameliorated the age-dependent decline in memory acquisition and retention, and caused alterations in the GABAergic system. These changes include increased levels of the neurotransmitters GABA and glutamate, increased expression of glutamic acid decarboxylase and the neuropeptide somatostatin and increased in the number of somatostatin-positive neurons. These specific alterations of the inhibitory system caused by taurine treatment oppose those naturally-occurring during aging, and suggest a protective role of taurine in this process. Increased understanding of age-related neurochemical changes in the GABAergic system will be important in elucidating the underpinnings of the functional changes of aging. Taurine might help forestall the age-related decline in cognitive functions through interaction with the GABAergic system.
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Envelhecimento/fisiologia , Taurina/fisiologia , Animais , Aprendizagem da Esquiva , Memória , CamundongosRESUMO
3'-Azido-3'-deoxythymidine (AZT) is the first clinically effective drug for the treatment of human immunodeficiency virus infection. The drug interaction with human serum albumin (HSA) has been an important component in understanding its mechanism of action, especially in drug distribution and in drug-drug interaction on HSA in the case of multi-drug therapy. We present here crystal structures of a ternary HSA-Myr-AZT complex and a quaternary HSA-Myr-AZT-SAL complex (Myr, myristate; SAL, salicylic acid). From this study, a new drug binding subsite on HSA Sudlow site 1 was identified. The presence of fatty acid is needed for the creation of this subsite due to fatty acid induced conformational changes of HSA. Thus, the Sudlow site 1 of HSA can be divided into three non-overlapped subsites: a SAL subsite, an indomethacin subsite and an AZT subsite. Binding of a drug to HSA often influences simultaneous binding of other drugs. From the HSA-Myr-AZT-SAL complex structure, we observed the coexistence of two drugs (AZT and SAL) in Sudlow site 1 and the competition between these two drugs in subdomain IB. These results provide new structural information on HSA-drug interaction and drug-drug interaction on HSA.
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Albumina Sérica/química , Albumina Sérica/metabolismo , Sítios de Ligação , Cristalografia por Raios X/métodos , Interações Medicamentosas , Humanos , Modelos Moleculares , Ligação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Ácido Salicílico/química , Ácido Salicílico/metabolismo , Zidovudina/química , Zidovudina/metabolismoRESUMO
A novel type 1 ribosome-inactivating protein (RIP) designated cucurmosin was isolated from the sarcocarp of Cucurbita moschata (pumpkin). Besides rRNA N-glycosidase activity, cucurmosin exhibits strong cytotoxicities to three cancer cell lines of both human and murine origins, but low toxicity to normal cells. Plant genomic DNA extracted from the tender leaves was amplified by PCR between primers based on the N-terminal sequence and X-ray sequence of the C-terminal. The complete mature protein sequence was obtained from N-terminal protein sequencing and partial DNA sequencing, confirmed by high resolution crystal structure analysis. The crystal structure of cucurmosin has been determined at 1.04A, a resolution that has never been achieved before for any RIP. The structure contains two domains: a large N-terminal domain composed of seven alpha-helices and eight beta-strands, and a smaller C-terminal domain consisting of three alpha-helices and two beta-strands. The high resolution structure established a glycosylation pattern of GlcNAc(2)Man(3)Xyl. Asn225 was identified as a glycosylation site. Residues Tyr70, Tyr109, Glu158 and Arg161 define the active site of cucurmosin as an RNA N-glycosidase. The structural basis of cytotoxicity difference between cucurmosin and trichosanthin is discussed.
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Antineoplásicos/química , Cucurbita/química , Proteínas de Plantas/química , Proteínas Inativadoras de Ribossomos Tipo 1/química , Animais , Antineoplásicos/isolamento & purificação , Domínio Catalítico , Linhagem Celular Tumoral , Cristalografia por Raios X , DNA de Plantas , Genoma de Planta , Glicosilação , Humanos , Folhas de Planta/química , Proteínas de Plantas/isolamento & purificação , Estrutura Secundária de Proteína , Proteínas Inativadoras de Ribossomos Tipo 1/isolamento & purificação , Análise de SequênciaRESUMO
Glutathione S-transferases (GSTs), a major family of detoxifying enzymes, play a pivotal role in insecticide resistance in insects. In the malaria vector Anopheles gambiae, insect-specific epsilon class GSTs are associated with resistance to the organochlorine insecticide DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane]. Five of the eight class members have elevated expression levels in a DDT resistant strain. agGSTe2 is considered the most important GST in conferring DDT resistance in A. gambiae, and is the only member of the epsilon class with confirmed DDT-metabolizing activity. A delta class GST from the same species shows marginal DDT-metabolizing activity but the activity of agGSTe2 is approximately 350x higher than the delta class agGST1-6. To investigate its catalytic mechanism and the molecular basis of its unusually high DDT-metabolizing ability, three agGSTe2 crystal structures including one apo form and two binary complex forms with the co-factor glutathione (GSH) or the inhibitor S-hexylglutathione (GTX) have been solved with a resolution up to 1.4A. The structure of agGSTe2 shows the canonical GST fold with a highly conserved N-domain and a less conserved C-domain. The binding of GSH or GTX does not induce significant conformational changes in the protein. The modeling of DDT into the putative DDT-binding pocket suggests that DDT is likely to be converted to DDE [1,1-dichloro-2,2-bis-(p-chlorophenyl)ethylene] through an elimination reaction triggered by the nucleophilic attack of the thiolate group of GS(-) on the beta-hydrogen of DDT. The comparison with the less active agGST1-6 provides the structural evidence for its high DDT-detoxifying activity. In short, this is achieved through the inclination of the upper part of H4 helix (H4'' helix), which brings residues Arg112, Glu116, and Phe120 closer to the GSH-binding site resulting in a more efficient GS(-)-stabilizing hydrogen-bond-network and higher DDT-binding affinity.
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Anopheles/enzimologia , DDT/metabolismo , Glutationa Transferase/química , Animais , Sítios de Ligação , Cristalografia por Raios X , Resistência a Medicamentos , Glutationa/química , Glutationa Transferase/metabolismo , Insetos Vetores , Insetos , Inseticidas/metabolismo , Malária/transmissão , Ligação Proteica , Conformação ProteicaRESUMO
Human urokinase-type plasminogen activator receptor (uPAR/CD87) is expressed at the invasive interface of the tumor-stromal microenvironment in many human cancers and interacts with a wide array of extracellular molecules. An anti-uPAR antibody (ATN615) was prepared using hybridoma technology. This antibody binds to uPAR in vitro with high affinity (K(d) approximately 1 nM) and does not interfere with uPA binding to uPAR. Here we report the crystal structure of the Fab fragment of ATN615 at 1.77 A and the analysis of ATN615-suPAR-ATF structure that was previously determined, emphasizing the ATN615-suPAR interaction. The complementarity determining regions (CDRs) of ATN615 consist of a high percentage of aromatic residues, and form a relatively flat and undulating surface. The ATN615 Fab fragment recognizes domain 3 of suPAR. The antibody-antigen recognition involves 11 suPAR residues and 12 Fab residues from five CDRs. Structural data suggest that Pro188, Asn190, Gly191, and Arg192 residues of uPAR are the key residues for the antibody recognition, while Pro189 and Arg192 render specificity of ATN615 for human uPAR. Interestingly, this antibody-antigen interface has a small contact area, mainly polar interaction with little hydrophobic character, yet has high binding strength. Furthermore, several solvent molecules (assigned as polyethylene glycols) were clearly visible in the binding interface between antibody and antigen, suggesting that solvent molecules may be important for the maximal binding between suPAR and ATN615 Fab. ATN615 undergoes small but noticeable changes in its CDR region upon antigen binding.
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Anticorpos Monoclonais/química , Cristalografia por Raios X/métodos , Epitopos/química , Receptores de Superfície Celular/química , Sequência de Aminoácidos , Arginina/química , Quimotripsina/química , Células HeLa , Humanos , Cinética , Dados de Sequência Molecular , Prolina/química , Ligação Proteica , Conformação Proteica , Receptores de Ativador de Plasminogênio Tipo Uroquinase , Homologia de Sequência de AminoácidosRESUMO
The title compound, C(16)H(14)O(7)·H(2)O, possesses a planar three-ring skeleton; its carbonyl, one of the two hydroxy and two of the three methoxy O atoms and the water mol-ecule form hydrogen bonds, giving rise to a layer structure.
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BACKGROUND: Protein sequence can be obtained through Edman degradation, mass spectrometry, or cDNA sequencing. High resolution X-ray crystallography can also be used to derive protein sequence information, but faces the difficulty in distinguishing the Asp/Asn, Glu/Gln, and Val/Thr pairs. Luffaculin 1 is a new type 1 ribosome-inactivating protein (RIP) isolated from the seeds of Luffa acutangula. Besides rRNA N-glycosidase activity, luffaculin 1 also demonstrates activities including inhibiting tumor cells' proliferation and inducing tumor cells' differentiation. RESULTS: The crystal structure of luffaculin 1 was determined at 1.4 A resolution. Its amino-acid sequence was derived from this high resolution structure using the following criteria: 1) high resolution electron density; 2) comparison of electron density between two molecules that exist in the same crystal; 3) evaluation of the chemical environment of residues to break down the sequence assignment ambiguity in residue pairs Glu/Gln, Asp/Asn, and Val/Thr; 4) comparison with sequences of the homologous proteins. Using the criteria 1 and 2, 66% of the residues can be assigned. By incorporating with criterion 3, 86% of the residues were assigned, suggesting the effectiveness of chemical environment evaluation in breaking down residue ambiguity. In total, 94% of the luffaculin 1 sequence was assigned with high confidence using this improved X-ray sequencing strategy. Two N-acetylglucosamine moieties, linked respectively to the residues Asn77 and Asn84, can be identified in the structure. Residues Tyr70, Tyr110, Glu159 and Arg162 define the active site of luffaculin 1 as an RNA N-glycosidase. CONCLUSION: X-ray sequencing method can be effective to derive sequence information of proteins. The evaluation of the chemical environment of residues is a useful method to break down the assignment ambiguity in Glu/Gln, Asp/Asn, and Val/Thr pairs. The sequence and the crystal structure confirm that luffaculin 1 is a new type 1 RIP.
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Cristalografia por Raios X/métodos , Glicoproteínas/química , Proteínas de Plantas/química , Conformação Proteica , Análise de Sequência de Proteína , Sítios de Ligação , Cristalização , Modelos Moleculares , Dados de Sequência Molecular , Proteínas Inativadoras de Ribossomos Tipo 1 , Homologia de Sequência de AminoácidosRESUMO
The X-ray single-crystal structure of natural salidroside (=2-(4-hydroxyphenyl)ethyl beta-D-glucopyranoside; 1), isolated from Cistanche deserticola, is reported for the first time, as well as its absolute configuration. The radical-scavenging activity of 1 towards the superoxide radical anion (O*2-) was determined experimentally by chemiluminescence measurements of the pyrogallol-luminol system, and compared to that of the corresponding aglycone, i.e., tyrosol (=4-(2-hydroxyethyl)phenol; 2).
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Antioxidantes/química , Glucosídeos/química , Glicosídeos/química , Fenóis/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Cistanche , Cristalografia por Raios X , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/isolamento & purificação , Sequestradores de Radicais Livres/farmacologia , Glucosídeos/isolamento & purificação , Glucosídeos/farmacologia , Glicosídeos/isolamento & purificação , Glicosídeos/farmacologia , Fenóis/isolamento & purificação , Fenóis/farmacologia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Caules de PlantaRESUMO
An avian analogue of human fronto-executive dysfunction was used to study the long-term effects of a repeated low dose of MK-801. MK-801 is known to selectively antagonize the excitatory N-methyl-d-aspartate receptors (NMDAR) and indirectly impair inhibitory related processes (GABA-AR). First, eight pigeons were divided into two groups, receiving either 0.15mg/kg MK-801 or saline (i.p.) 1-hour prior to each session. Thirty 90-min sessions of a Differential Reinforcement of Low Rate of Response (DRL-10s) schedule were run over 3-months. Both overall number of responses and efficiency were unaffected by treatment, establishing a sub-threshold motoric dose. Then, another eight pigeons, treated identically, were given an operant visual discrimination task. Results demonstrated impairment of the fronto-striatal function of both excitatory and inhibitory processes in the MK-801 group during the entire 3-months. A 30-session treatment cross-over showed that the Saline-to-MK-801 group was unaffected, whereas the MK-801-to-Saline group exhibited rapid recovery of inhibitory control, however excitatory control did not fully recover. Together, these results suggested that the NMDAR system is involved in the acquisition of excitatory learning, but only in the expression of inhibitory learning. Our findings were discussed in terms of the value of avian models in translational research. Furthermore, our results were examined within the context of the NIH Research Domain of Criteria initiative and the role of NMDAR disruption, which underlie executive dysfunction in various neuropsychiatric disorders. Finally, our findings suggested that the potential long-term effects of the clinical and recreational use of NMDAR antagonists require further study.