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1.
Artigo em Russo | MEDLINE | ID: mdl-38529868

RESUMO

OBJECTIVE: To assess the validity of the screening method based on EEG analysis using predictive analytics algorithms with the calculation of linear discriminant functions (LDFs), in comparison with a classification system based on psychometric self-report scales. MATERIAL AND METHODS: A comparative cross-sectional study with partial blinding involving healthy volunteers was conducted at two investigational sites. The calculated scores of LDFs used to assess risks of impulsivity, depression and anxiety acted as quantitative characteristics of subjects' mental state. Testing included completing psychometric scales. RESULTS: As a result of the performed validation of the original screening method based on EEG analysis in comparison with the scores of psychometric scales chosen as a reference method, satisfactory results were obtained with the best parameters of sensitivity, specificity, and accuracy for detecting high levels of impulsivity associated with pronounced aggressiveness. Of considerable interest is also the direct correlation found between high levels of LDF impulsivity scores and high levels of self-rated aggression on a psychometric scale (BPAQ-24). CONCLUSION: The results open up the possibility of using the proposed method to predict a number of emotional and behavioral characteristics of subjects, including a high risk of aggressive behavior as part of professional selection.


Assuntos
Transtornos de Ansiedade , Eletroencefalografia , Humanos , Projetos Piloto , Estudos Transversais , Transtornos de Ansiedade/psicologia , Medição de Risco , Psicometria , Reprodutibilidade dos Testes
2.
Dokl Biol Sci ; 513(1): 368-373, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37700103

RESUMO

A morphological description is provided for a unique find of a frozen mummified subfossil brown bear (Ursus arctos L., 1758), found for the first time ever. The find is a well-preserved bear carcass of approximately 3500 years in age. Results of computed tomography and DNA testing are discussed.


Assuntos
Ursidae , Animais , Ursidae/classificação
3.
Bioorg Med Chem Lett ; 79: 129080, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36414175

RESUMO

Smallpox was eradicated >40 years ago but it is not a reason to forget forever about orthopoxviruses pathogenic to humans. Though in 1980 the decision of WHO to cease vaccination against smallpox had seemed logical, it led to the decrease of cross immunity against other infections caused by orthopoxviruses. As a result, in 2022 the multi-country monkeypox outbreak becomes a topic of great concern. In spite of existing FDA-approved drugs for the treatment of such diseases, the search for new small-molecule orthopoxvirus inhibitors continues. In the course of this search a series of novel 2-aryl-1-hydroxyimidazole derivatives containing ester or carboxamide moieties in position 5 of heterocycle has been synthesized and tested for activity against Vaccinia virus in Vero cell culture. Some of the compounds under consideration revealed a selectivity index higher than that of the reference drug Cidofovir. The highest selectivity index SI = 919 was exhibited by ethyl 1-hydroxy-4-methyl-2-[4-(trifluoromethyl)phenyl]-1H-imidazole-5-carboxylate 1f. The most active compound also demonstrated inhibitory activity against the cowpox virus (SI = 20) and the ectromelia virus (SI = 46).


Assuntos
Antivirais , Orthopoxvirus , Infecções por Poxviridae , Humanos , Amidas , Antivirais/farmacologia , Ácidos Carboxílicos , Ésteres , Imidazóis/farmacologia , Orthopoxvirus/efeitos dos fármacos , Varíola , Infecções por Poxviridae/tratamento farmacológico
4.
Mol Biol (Mosk) ; 56(4): 546-556, 2022.
Artigo em Russo | MEDLINE | ID: mdl-35964311

RESUMO

The mechanisms for the protection of the human body from viral or bacterial agents are extremely diverse. In one such mechanism, an important role belongs to the cytidine deaminase APOBEC3 family, which is the factor of congenital immunity and protects the organism from numerous viral agents. One of the proteins of this family, APOBEC3G, is able to protect against Human Immunodeficiency Virus type 1 in the absence of viral protein Vif. In turn, Vif opposes APOBEC3G action, causing polyubiquity of the protein and degradation in the proteasome. The review describes possible ways to increase the anti-HIV activity of APOBEC3G, giving it resistance to viral protein Vif, as well as potential approaches to the use of modified APOBEC3G in gene therapy for HIV.


Assuntos
HIV-1 , Produtos do Gene vif do Vírus da Imunodeficiência Humana , Desaminase APOBEC-3G/genética , Citidina Desaminase/genética , Citidina Desaminase/metabolismo , Terapia Genética , HIV-1/metabolismo , Humanos , Produtos do Gene vif do Vírus da Imunodeficiência Humana/genética , Produtos do Gene vif do Vírus da Imunodeficiência Humana/metabolismo
5.
Appl Magn Reson ; 53(7-9): 1053-1067, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34522067

RESUMO

In this work, we investigated the redox transients of a number of water-soluble spin labels upon their interactions with Photosystem II (PS II) core complexes isolated from spinach leaves. We have found that the reactivity of nitroxide radicals, determined by the rate of their reduction upon illumination of PS II, depends on the chemical structure of radicals and the capability of their coming close to low-potential redox centers of photoactive PS II complexes. An enhanced capability of nitroxide radicals to accept electrons from PS II correlates with their chemical structure. Nitroxide radicals NTI (2,2,5,5-tetramethyl-4-nitromethylene-3-imidazolidine-N-oxyl) and Tacet (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl-acetate), containing polar groups, appear to be most efficient acceptors of electrons donated by PS II compared to neutral (TEMPOL, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) or positively charged (Tamine, 4-amino-2,2,6,6-tetramethylpiperidine-l-oxyl) spin labels. We assume that enhanced reactivities of polar nitroxide radicals, NTI and Tacet, are determined (1) by their relatively high redox potentials, providing the possibility to accept electrons from PS II, and (2) by their affinities to the closest binding sites on the surface of PS II in the vicinity of the primary plastoquinone acceptor PQA (12-14 Å) or/and in the intraprotein cavity for the secondary plastoquinone PQB (~ 22 Å).

6.
Khirurgiia (Mosk) ; (7): 84-89, 2021.
Artigo em Russo | MEDLINE | ID: mdl-34270199

RESUMO

Differential diagnosis of pulmonary infiltrates is difficult due to the absence of specific clinical and radiological manifestations. Differential diagnosis of pulmonary infiltrates usually includes the following «triad¼: pneumonia, tuberculosis, lung cancer. Diagnosis of pulmonary tuberculosis is based on microbiological examination of sputum and bronchoscopic respiratory samples - bronchial washing and bronchoalveolar lavage. Efficiency of molecular genetic methods (including express tests) in detecting M. tuberculosis DNA can reach 91-98%. Therefore, treatment may be started without data of microbiological examination. Nevertheless, there are rare cases of false-positive results of PCR in patients with non-tuberculous lung lesions. This aspect often results false diagnosis and delayed verification of true cause of lung lesion. Another adverse effect is associated with anti-tuberculosis therapy. Endoscopic transbronchial lung biopsy and its modern version (transbronchial cryobiopsy) as a minimally invasive diagnostic procedure are performed in such patients. These methods require a sufficiently high experience and qualification of specialist and following such aspects as navigation techniques and balloon bronchial blocking. We present this clinical case as a demonstration of modern possibilities of multimodal navigational bronchoscopic diagnosis with transbronchial cryobiopsy for local pulmonary infiltrate.


Assuntos
Broncoscopia , Pneumopatias , Biópsia , Diagnóstico Diferencial , Endossonografia , Humanos , Pulmão/diagnóstico por imagem
7.
J Virol Methods ; 289: 114056, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33359615

RESUMO

Obtaining a pure recombinant Modified Vaccinia Ankara (MVA) virus is a multistage, time-consuming procedure. We describe a novel single-tube real-time PCR which enables determination of the amount of wild type and recombinant viruses and their ratio in plaques. Use of the real-time PCR significantly reduce the time and efforts needed to obtain purified recombinant MVA. The new approach has been applied to generate recombinant MVAs encoding different SARS-COV-2 antigens.


Assuntos
Antígenos Virais , Vetores Genéticos , SARS-CoV-2/genética , Vaccinia virus/isolamento & purificação , Animais , Linhagem Celular , Humanos , Reação em Cadeia da Polimerase em Tempo Real
8.
Bull Exp Biol Med ; 170(2): 207-210, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33263846

RESUMO

We compared absolute bioavailability of the chemical substance of the anti-smallpox preparation NIOCH-14 and chemical compound ST-246 active against orthopoxviruses after oral administration to mice in doses of 10 and 50 µg/g and intravenous administration to mice in a dose of 2 µg/g body weight. The absolute bioavailability of NIOCH-14 is comparable with the absolute bioavailability of ST-246.


Assuntos
Disponibilidade Biológica , Ácidos Dicarboxílicos/farmacocinética , Varíola/tratamento farmacológico , Animais , Área Sob a Curva , Benzamidas/farmacocinética , Calibragem , Modelos Animais de Doenças , Feminino , Infusões Intravenosas , Isoindóis/farmacocinética , Masculino , Camundongos , Camundongos Endogâmicos ICR , Fatores de Tempo , Vírus da Varíola
9.
Bull Exp Biol Med ; 168(1): 141-144, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31761987

RESUMO

We studied the effect of peptide AEDG on telomere length and mitotic index of PHA-stimulated blood lymphocytes from young (18-22 years, N=5) and middle-aged (49-54 years, N=6) men. In the younger age group, no significant changes in the mitotic index were detected, while in the middle-aged group, a decrease in this parameter was found in one case. The relative length of telomeric regions of metaphase chromosomes was evaluated by in situ fluorescence hybridization with DNA probes specific to telomeres. After incubation with peptide AEDG, significant changes in the relative telomere length were found in 7 of 11 individuals (3 cases in the younger age group and 4 cases in the middle age group). Significant increase in telomere length after exposure to peptide AEDG was revealed in 5 cases, including two individuals of the younger age group (by 41 and 55%) and three individuals of the middle age group (by 156, 18, and 76%). In one individual of the younger age group and in one of the middle-age group, a significant decrease in telomere length (by 37 and 15%, respectively) was found. A tendency to normalization of telomere lengths was noted: this parameter increased in individuals with initially lower telomere length relative to the group mean value and decreased in individuals with initially longer telomeres compared to the mean length in the group.


Assuntos
Linfócitos/efeitos dos fármacos , Linfócitos/metabolismo , Fito-Hemaglutininas/farmacologia , Telômero/efeitos dos fármacos , Telômero/metabolismo , Adolescente , Adulto , Humanos , Hibridização in Situ Fluorescente , Ativação Linfocitária/efeitos dos fármacos , Pessoa de Meia-Idade , Índice Mitótico , Adulto Jovem
10.
Langmuir ; 35(38): 12326-12338, 2019 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-31480848

RESUMO

An integrated approach is applied to reveal fine changes in the surface-normal structure of 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine (DMPS) monolayers at the air-lipid-water interface occurring in a liquid expanded (LE)-liquid condensed (LC) transition. The combination of the Langmuir monolayer technique, X-ray reflectometry, and molecular dynamics (MD) modeling provides new insight into the molecular nature of electrostatic phenomena in different stages of lipid compression. A homemade setup with a laboratory X-ray source (λ = 1.54 Å) offers a nondestructive way to reveal the structural difference between the LE and LC phases of the lipid. The electron density profile in the direction normal to the interface is recovered from the X-ray reflectivity data with the use of both model-independent and model-based approaches. MD simulations of the DMPS monolayer are performed for several areas per lipid using the all-atom force field. Using the conventional theory of capillary waves, a comparison is made between the electron density profiles reconstructed from the X-ray data and those calculated directly from MD modeling, which demonstrates remarkable agreement between the experiment and simulations for all selected lipid densities. This confirms the validity of the simulations and allows an analysis of the contributions of the hydrophobic tails and hydrated polar groups to the electron density profile and to the dipole component of the electric field at the interface. According to the MD data, the dependence of the Volta potential on the area per lipid in the monolayer has a different molecular nature below and above the phase transition. In the LE state of the monolayer, the potential is determined mostly by the oriented water molecules in the polar region of the lipid. In the LE-LC transition, these molecules are displaced to the bulk, and their effect on the Volta potential becomes insignificant compared with the contribution of the hydrophobic tails. The hydrophobic tails are highly ordered in the state of the liquid crystal so that their dipole moments entirely determine the growth of the potential upon compression up to the monolayer collapse.

11.
Bull Exp Biol Med ; 167(3): 400-403, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31350655

RESUMO

A new alloplastic high-permeable material based on tricalcium phosphate with Kelvin architectonics created by stereolithographic 3D-printing was studied in vivo. A monocortical defect of the femur was modeled in rats and the material was implanted into the defect area. In 24 weeks, the animals were euthanized and histological examination of the defect area was performed. One femur fracture with fixator migration was recorded after implantation of the studied material and the reference chronOS synthetic material. The studied material demonstrated better osteoconductive properties then traditional osteoplastic material, which was seen from greater number of bone trabeculae and their area in the defect area.


Assuntos
Regeneração Óssea/fisiologia , Substitutos Ósseos/uso terapêutico , Osso Esponjoso/crescimento & desenvolvimento , Diáfises/anormalidades , Fêmur/anormalidades , Animais , Transplante Ósseo/métodos , Fosfatos de Cálcio/uso terapêutico , Diáfises/patologia , Modelos Animais de Doenças , Fêmur/patologia , Porosidade , Impressão Tridimensional , Ratos , Ratos Wistar
12.
Bull Exp Biol Med ; 166(4): 489-493, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30788741

RESUMO

We propose an approach that allows simultaneous determination of the levels of M and G isotypes of antibodies to the panel of glycans using microarrays. The level of IgG antibodies to 3'-O-su-Lea glycan detects patients with colorectal cancer with a sensitivity of 69.77% and specificity of 62.75%. The percentage of correctly classified colorectal cancer patients with the use of a combination of two markers IgM antibodies to glycans 3'-sialyl-TF and 3'-O-su-Lea is as high as 74.23%. The levels of IgM antibodies to 3'-O-su-Lea glycan differ significantly in patients with and without regional metastases. The levels of some of antiglycan IgM or IgG antibodies differed significantly in patients with tumors of different location and differentiation.


Assuntos
Anticorpos/imunologia , Neoplasias Colorretais/imunologia , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Polissacarídeos/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Anti-Idiotípicos/imunologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
13.
Biochemistry (Mosc) ; 82(11): 1249-1268, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29223152

RESUMO

This review considers the state-of-the-art on mechanisms and alternative pathways of electron transfer in photosynthetic electron transport chains of chloroplasts and cyanobacteria. The mechanisms of electron transport control between photosystems (PS) I and II and the Calvin-Benson cycle are considered. The redistribution of electron fluxes between the noncyclic, cyclic, and pseudocyclic pathways plays an important role in the regulation of photosynthesis. Mathematical modeling of light-induced electron transport processes is considered. Particular attention is given to the electron transfer reactions on the acceptor side of PS I and to interactions of PS I with exogenous acceptors, including molecular oxygen. A kinetic model of PS I and its interaction with exogenous electron acceptors has been developed. This model is based on experimental kinetics of charge recombination in isolated PS I. Kinetic and thermodynamic parameters of the electron transfer reactions in PS I are scrutinized. The free energies of electron transfer between quinone acceptors A1A/A1B in the symmetric redox cofactor branches of PS I and iron-sulfur clusters FX, FA, and FB have been estimated. The second-order rate constants of electron transfer from PS I to external acceptors have been determined. The data suggest that byproduct formation of superoxide radical in PS I due to the reduction of molecular oxygen in the A1 site (Mehler reaction) can exceed 0.3% of the total electron flux in PS I.


Assuntos
Transporte de Elétrons , Complexo de Proteína do Fotossistema I/metabolismo , Cloroplastos/química , Cloroplastos/metabolismo , Cianobactérias/química , Cianobactérias/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Cinética , Modelos Químicos , Oxigênio/metabolismo , Quinonas/metabolismo
14.
Mol Biol (Mosk) ; 51(5): 752-760, 2017.
Artigo em Russo | MEDLINE | ID: mdl-29116061

RESUMO

Colorectal cancer (CRC) is one of the most common primary malignancies. Early stages of the disease are asymptomatic in the majority of cases, leading to late detection and high mortality. Available noninvasive diagnostic techniques are limited in sensitivity and specificity, and designing new ones is still a pressing problem. Exosomes are membrane-derived microvesicles secreted into human biological fluids and provide a novel way to assess the course of an oncology disease. The review describes the repertoire of exosomal surface biomarkers found in the blood of CRC patients and the prospects of employing multiplexed tests for exosomal markers in early noninvasive diagnosis of cancer.


Assuntos
Biomarcadores Tumorais/metabolismo , Micropartículas Derivadas de Células/metabolismo , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/metabolismo , Exossomos/metabolismo , Animais , Micropartículas Derivadas de Células/patologia , Neoplasias Colorretais/patologia , Exossomos/patologia , Humanos
15.
Mol Biol (Mosk) ; 51(5): 817-823, 2017.
Artigo em Russo | MEDLINE | ID: mdl-29116068

RESUMO

Exosomes are cell-derived vesicles that are secreted by both normal and cancer cells. Over the last decade, a few studies have revealed that exosomes cross talk and/or influence major tumor-related pathways such as angiogenesis and metastasis involving many cell types within the tumor microenvironment. The protein composition of the membrane of an exosome reflects that of the membrane of the cell of origin. Because of this, tumor-derived exosomes differ from exosomes that are derived from normal cells. The detection of tumor exosomes and analysis of their molecular composition hold promise for diagnosis and prognosis of cancer. Here, we present hydrogel microarrays (biochips), which contain a panel of immobilized antibodies that recognize tetraspanins (CD9, CD63, CD81) and prognostic markers for colorectal cancer (A33, CD147). These biochips make it possible to analyze the surface proteins of either isolated exosomes or exosomes that are present in the serum samples without isolation. These biochips were successfully used to analyze the surface proteins of exosomes from serum that was collected from a colorectal cancer patient and healthy donor. Biochip-guided immunofluorescent analysis of the exosomes has made it possible for us to detect the A33 antigen and CD147 in the serum sample of the colorectal cancer patient with normal levels of CEA and CA19-9.


Assuntos
Antígenos CD/sangue , Biomarcadores Tumorais/sangue , Neoplasias Colorretais/sangue , Exossomos/metabolismo , Hidrogéis/química , Dispositivos Lab-On-A-Chip , Procedimentos Analíticos em Microchip/métodos , Proteínas de Neoplasias/sangue , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
16.
Bull Exp Biol Med ; 163(5): 646-649, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28944423

RESUMO

Using immunofluorescence with specific antibodies, we analyzed DNA hydroxymethylation in uncultured cells from 25 human uterine leiomyomas considering the menstrual cycle phase during surgery and the presence of MED12 gene mutations. It was found that each tumor node had specific DNA hydroxymethylation level that did not depend on the presence of mutations in MED12 gene, but depended on the phase of menstrual cycle. The degree of DNA hydroxymethylation was significantly lower in cells of leiomyomas excised during the luteal phase compared to the follicular phase (p=0.0431). Hormonal status changing at various phases of menstrual cycle is a factor affecting DNA hydroxymethylation in leiomyoma cells.


Assuntos
Análise Mutacional de DNA/métodos , Hidroxilação/fisiologia , Leiomioma/metabolismo , Complexo Mediador/genética , Ciclo Menstrual/genética , Neoplasias Uterinas/genética , Adulto , Feminino , Humanos , Hidroxilação/genética , Ciclo Menstrual/fisiologia , Pessoa de Meia-Idade , Mutação/genética , Software , Neoplasias Uterinas/metabolismo
17.
Mol Biol (Mosk) ; 51(2): 227-239, 2017.
Artigo em Russo | MEDLINE | ID: mdl-28537230

RESUMO

Allergic and autoimmune diseases represent immunopathological reactions of an organism to antigens. Despite that the allergy is a result of exaggerated immune response to foreign antigens (allergens) and autoimmune diseases are characterized by the pathological response to internal antigens (autoantigens), the underlying mechanisms of these diseases are probably common. Thus, both types of diseases represent variations in the hypersensitivity reaction. A large percentage of both the adult and pediatric population is in need of early diagnostics of these pathologies of the immune system. Considering the diversity of antibodies produced in allergic and autoimmune disease and the difficulties accompanying clinical diagnosing, molecular diagnostics of these pathological processes should be carried out in several stages, including screening and confirmatory studies. In this review, we summarize the available data on the molecular diagnostics and therapy of allergic and autoimmune diseases and discuss the basic similarities and differences in the mechanisms of their development.


Assuntos
Doenças Autoimunes , Hipersensibilidade , Técnicas de Diagnóstico Molecular/métodos , Animais , Doenças Autoimunes/diagnóstico , Doenças Autoimunes/imunologia , Doenças Autoimunes/terapia , Humanos , Hipersensibilidade/diagnóstico , Hipersensibilidade/imunologia , Hipersensibilidade/terapia
19.
Mol Biol (Mosk) ; 49(5): 790-9, 2015.
Artigo em Russo | MEDLINE | ID: mdl-26510597

RESUMO

The objective of this work was to obtain preparations of recombinant squamous-cell carcinoma antigens (serpins B3 and B4) and to investigate their interactions with different monoclonal antibodies using hydrogel-based microarrays (biochips). Two genetic constructs encoding full-length serpin B3 and serpin B4 molecules were created to produce recombinant SPB3 and SPB4 proteins carrying a N-terminal His6-tag. Monoclonal antibodies against serpin B3 (H3, C5, H5, H81, and G9) were also obtained. An experimental gel-based biological microchip was designed to contain gel elements that carry immobilized antibodies against SPB3, immobilized commercial monoclonal SCC107 and SCC140 antibodies against squamous-cell carcinoma antigen (SCCA), and gel elements with immobilized SPB3 or SPB4. Judging by the specificity of recombinant SPB3 and SPB4, which bind to monoclonal antibodies against SCCA and, according to the manufacturer's data, can recognize conformational epitopes of both SPB3 and SPB4, it was concluded that the obtained recombinant serpins had the correct tertiary structure. A biochip-based direct immunoassay showed that SPB4 could bind effectively only to SCC107 and SCC140 antibodies, while SPB3 interacted specifically not only with these antibodies, but also with H3 and C5 monoclonal antibodies. Using biochip-based sandwich immunoassay, a pair of monoclonal antibodies SCC107/C5 that interacted specifically with serpin B3 but did not interact with serpin B4 was identified. Thus, it has been demonstrated that serpin B3 can be selectively determined in the presence of highly homologous serpin B4 using a biochip-based assay.


Assuntos
Anticorpos Monoclonais/química , Antígenos de Neoplasias/química , Epitopos/química , Hidrogéis/química , Serpinas/química , Animais , Anticorpos Monoclonais/biossíntese , Anticorpos Monoclonais/imunologia , Antígenos de Neoplasias/genética , Antígenos de Neoplasias/imunologia , Carcinoma de Células Escamosas/química , Clonagem Molecular , Epitopos/genética , Epitopos/imunologia , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Humanos , Dispositivos Lab-On-A-Chip , Camundongos , Camundongos Endogâmicos BALB C , Análise em Microsséries , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Serpinas/genética , Serpinas/imunologia
20.
Acta Crystallogr D Biol Crystallogr ; 71(Pt 5): 1087-94, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25945574

RESUMO

Octahaem cytochrome c nitrite reductase from the bacterium Thioalkalivibrio nitratireducens catalyzes the reduction of nitrite to ammonium and of sulfite to sulfide. The reducing properties of X-ray radiation and the high quality of the enzyme crystals allow study of the catalytic reaction of cytochrome c nitrite reductase directly in a crystal of the enzyme, with the reaction being induced by X-rays. Series of diffraction data sets with increasing absorbed dose were collected from crystals of the free form of the enzyme and its complexes with nitrite and sulfite. The corresponding structures revealed gradual changes associated with the reduction of the catalytic haems by X-rays. In the case of the nitrite complex the conversion of the nitrite ions bound in the active sites to NO species was observed, which is the beginning of the catalytic reaction. For the free form, an increase in the distance between the oxygen ligand bound to the catalytic haem and the iron ion of the haem took place. In the case of the sulfite complex no enzymatic reaction was detected, but there were changes in the arrangement of the active-site water molecules that were presumably associated with a change in the protonation state of the sulfite ions.


Assuntos
Citocromos a1/química , Citocromos a1/metabolismo , Citocromos c1/química , Citocromos c1/metabolismo , Ectothiorhodospiraceae/enzimologia , Heme/química , Nitrato Redutases/química , Nitrato Redutases/metabolismo , Nitritos/metabolismo , Conformação Proteica/efeitos da radiação , Sulfitos/metabolismo , Domínio Catalítico , Cristalografia por Raios X , Citocromos a1/efeitos da radiação , Citocromos c1/efeitos da radiação , Ectothiorhodospiraceae/efeitos da radiação , Modelos Moleculares , Nitrato Redutases/efeitos da radiação , Nitritos/química , Nitritos/efeitos da radiação , Ligação Proteica , Efeitos da Radiação , Especificidade por Substrato , Sulfitos/química , Sulfitos/efeitos da radiação , Raios X
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