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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Charakterizace glutamátkarboxypeptidasy II, jejích blízkých homologů a jejich interakcí s ligandy / Characterization of Glutamate Carboxypeptidase II, its Close Homologs and their Interaction with Ligands

Tykvart, Jan January 2015 (has links)
Cancer, group of diseases characterized by an uncontrolled cell growth, represents one of the great challenges of modern clinical research. Currently, the standard treatment of the cancer disease relies mainly on the whole body exposition to various factors, which targets the dividing cells, combined with surgical resection of the tumor. Unfortunately, this treatment is sometimes accompanied by numerous severe side-effects (e.g., nausea, loss of hair, infertility etc.). Therefore, in the past 40 years enormous resources and effort have been invested into finding a way how to specifically target and destroy the cancerous cells. This goal has been primarily addressed by the search for molecules, mainly proteins, which are predominantly expressed in the cancerous tissues compared to the healthy cells. Glutamate carboxypeptidase II (GCPII), also known as prostate specific membrane antigen (PSMA), represents such a target since it is highly expressed in a prostate carcinoma as well as in a solid tumor neovasculature. Additionally, GCPII is widely used as a model target molecule for proof-of-principle studies on targeted drug delivery. GCPII thorough biochemical characterization is essential for its appropriate use. Therefore, our laboratory has been investigating GCPII from various perspectives for more...
62

Interaktion zytosolischer Peptidasen und deren Rolle bei der MHC-Klasse-I-Antigenpräsentation des HLA-A2-restingierten HCMV pp65495-503 Epitops

Paschke, Julia 20 January 2014 (has links)
MHC-Klasse-I präsentierte Epitope werden überwiegend durch den proteasomalen Abbau von Poly-Ubiquitin markierten Proteinen und defekten ribosomalen Produkten (DRiPs) generiert. Die post-proteasomale Prozessierung durch zytosolische Exo- und Endopeptidasen führt jedoch hauptsächlich zur Epitop-Zerstörung und nur ein sehr geringer Anteil der Peptide entkommt der Degradation. Bisher ist noch unklar, wie die enzymatischen Aktivitäten des heterogenen Peptidase-Pools im Zytosol die finale Epitop-Prozessierung beeinflussen. In der vorliegenden Arbeit wurden heteromere Interaktionen von zytosolischen Peptidasen analysiert und ihre Wirkung auf die Prozessierung und Präsentation von proteasomal generier-ten Vorläuferpeptiden in Bezug auf die HCMVpp65495-503 Epitop-Generierung untersucht. Glycerolgradientenzentrifugationen und Immunpräzipitationsexperimente zeigten, dass die zytosolischen Peptidasen Nardilysin (NRDc) und Aminopeptidase-B (AP-B) in den gleichen Fraktionen sedimentieren und zu heteromeren Komplexen interagieren. Die siRNA- abhängige Reduktion der Proteinexpression beider Peptidasen hatte einen positiven Effekt auf die HCMVpp65 spezifische CTL-Antwort. Demnach vermindert der Peptidase-Komplex die HCMVpp65-spezifische Epitop-Präsentation auf der Zelloberfläche. Im Gegensatz dazu bewirkte ein in vitro rekonstituierter trimerer Peptidase-Komplex jedoch die verstärkte HCMVpp65 Epitop-Generierung aus einem proteasomal generierten Vorläuferpeptid. Auf der anderen Seite führte gereinigte AP-B zu der anhaltenden Zerstörung des Epitops. Die Ergeb-nisse deuten somit darauf hin, dass sowohl einzelne als auch verschiedene Interaktionen von zytosolischen Peptidasen die Prozessierung und Präsentation des HCMVpp65-Epitops unterschiedlich modulieren und somit die HCMVpp65-spezifische antivirale Immunantwort beeinflussen. / MHC class I presented antigens are generated by the degradation of poly- ubiquitinated pro-teins and defective ribosomal products (DRiPs) by a major protease, the 26S proteasome. However, the post- proteasomal processing by cytosolic exo-and endopeptidases mainly leads to epitope destruction and only a very small proportion of the peptides escape degradation. So far, it is still unclear how the enzymatic activity of the heterogeneous pool of peptidases in the cytosol affects final epitope processing and therewith immune response. In the present work heteromeric interactions of cytosolic peptidases and their effect on pro-cessing and presentation of proteasomal generated peptides were analysed with regard to HCMVpp65495-503 epitope generation. Glycerol gradient centrifugation and immunoprecipitation experiments indicate that the cyto-solic peptidases Nardilysine (NRDc) and Aminopeptidase B (AP-B) sediment in the same fractions and interact to heteromeric complexes. The siRNA dependent reduction of protein expression of these two peptidases had a positive effect on the HCMVpp65 specific CTL re-sponse. Thus the peptidase complex reduces HCMVpp65 epitope presentation on the cell sur-face possibly due to epitope destruction. In contrast to the findings of the CTL assays, an in vitro reconstituted trimeric peptidase complex resulted in the increased generation of HCMVpp65 epitopes from a proteasomal generated peptide precursor. On the other hand pu-rified AP-B led to the ongoing destruction of the epitope. The findings obtained show that single cytosolic peptidases and various interactions of cytosolic peptidases regulate the pro-cessing and presentation of the HCMVpp65 epitope differently, thereby influencing the HCMV-specific antiviral immune response.
63

Development of novel vaccines for the concurrent immunisation against multiple dengue virus serotypes

Liew, Steven Christopher January 2006 (has links)
A major obstacle to the development of dengue virus (DENV) vaccines has been the need to immunise concurrently against each of the four DENV serotypes in order to avoid sensitising recipients to developing severe DENV infections. A problem already encountered with live attenuated tetravalent DENV vaccines has been the difficulty in eliciting adequate immune responses against all four DENV serotypes in human hosts. This could have been due to variations in the antigenicity and/or the replication rates of the four DENV serotypes. Non-replicating DNA vaccines avoid the issue of different replication rates. Currently, only DENV-1 and DENV-2 DNA vaccines have been evaluated. In this study, a number of DNA vaccines for each of the four DENV serotypes were developed and their immunogenicity was evaluated in outbred mice. These vaccines included DNA vaccines encoding the DENV prM-E protein genes derived from the four DENV serotypes (pVAX-DEN1, -DEN2, -DEN3 and -DEN4), and DNA vaccines encoding DENV prM and hybrid-E protein genes derived from multiple DENV serotypes. The hybrid-E protein genes were constructed by substituting either domains I and II, domain III, and/or the stem-anchor region from the E protein of one DENV serotype with the corresponding region from another DENV serotype. A number of superior DNA vaccines against each of the four DENV serotypes were identified based on their ability to elicit high titres (≥40, FFURNT50) of neutralising antibodies against the corresponding DENV in mice. The superior DNA vaccines against DENV-1 were pVAX-DEN1, pVAX-C2M2E211, pVAX-C2M2E122 and pVAX-C2M1E122. The superior DNA vaccine against DENV-2 was pVAX-C2M1E122 and the superior DNA vaccines against DENV-3 were pVAX-DEN3 and pVAX-C2M3E344. The superior DNA vaccines against DENV-4 were pVAX-C2M3E344, pVAX-C2M4E434 and pVAX-C2M4E433. Each of these DNA vaccines could provide effective protection against infection by the corresponding DENV serotypes. This is the first study to describe the development of DNA vaccines against DENV-3 and DENV-4. However, mice immunised with a tetravalent DENV DNA vaccine, composed of a DNA vaccine encoding the prM-E protein genes from each of the four DENV serotypes (pVAX-DEN1-4), elicited high titres of neutralising antibodies against DENV-1 and DENV-3 only. Nevertheless, the results from this study suggested that a tetravalent DENV DNA vaccine, composed of pVAX-DEN1, pVAX-C2M1E122, pVAX-DEN3 and pVAX-C2M4E434, may provide effective concurrent protection against infection by each of the four DENV serotypes. In addition, mice immunised with pVAX-C2M1E122, which encoded a hybrid-E protein gene derived from DENV-1 and DENV-2, elicited high titres of anti-DENV-1 and anti-DENV-2 neutralising antibodies, and mice immunised with pVAX-C2M3E344, which encoded a hybrid-E protein gene derived from DENV-3 and DENV-4, elicited high titres of anti-DENV-3 and anti-DENV-4 neutralising antibodies. This result suggested that the co-immunisation of these two hybrid-E DNA vaccines also may provide effective concurrent protection against infection by each of the four DENV serotypes. Extracellular E proteins, believed to be in the form of recombinant subviral particles (RSPs), were recovered from the tissue culture supernatant of all DNA vaccine-transfected mammalian cells by ultracentrifugation, except for cells transfected with the pVAX-C2M2E122 hybrid-E DNA vaccine. Western blotting with the monoclonal antibody 4G2 (flavivirus cross-reactive) demonstrated that the extracellular E proteins expressed by the DNA vaccines were synthesized and cleaved in a manner similar to that of native DENV E proteins. In addition, mammalian cells transfected with pVAX-DEN1, pVAX-DEN2 or pVAX-DEN3 secreted higher amounts of extracellular E proteins than cells transfected with pVAX-DEN4. The amount of extracellular E protein secreted by pVAX-DEN4-transfected cells increased when the c-region of the prM/E signal peptidase cleavage site was made more polar. In contrast, decreasing the polarity of the c-region of the C/prM signal peptidase cleavage site of pVAX-DEN4 resulted in no detectable extracellular E proteins from pVAX-DEN4-transfected cells. This result suggested that the amount of extracellular E proteins secreted by cells transfected with DNA expressing the DENV prM-E protein genes may be dependent of the efficiency of C/prM and prM/E protein cleavages by host-derived signal peptidases. Mice immunised with the mutated pVAX-DEN4, which was capable of expressing large amounts of extracellular E proteins in vitro, produced significantly higher concentrations of Th1-type anti-DENV-4 antibodies than mice immunised with the unmodified pVAX-DEN4, but failed to produce detectable levels of anti-DENV-4 neutralising antibodies. In contrast, increasing the ratio of CpG-S to CpG-N motifs in the pVAX-DEN2 DNA vaccine by incorporating either an additional CpG-S motif, or an antibiotic resistance gene with a high ratio of CpG-S to CpG-N motifs, resulted in a significant increase in both the concentration of Th1-type anti-DENV-2 antibodies and the titres of anti-DENV-2 neutralising antibodies in immunised mice. This result suggested that increasing the amount of CpG-S motifs in DENV DNA vaccines may present an simple and effective approach to increasing the immunogenicity of the DENV DNA vaccines.
64

Variation in milk protein composition and its importance for the quality of cheese milk /

Wedholm, Anna, January 2008 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2008. / Härtill 5 uppsatser.
65

Analyse préliminaire du rôle des "Ubiquitin specific peptidases" et de l'axe USP7-MDM2-TP53-CDKN1A dans les leucémies myéloïdes aiguës

Séguin-Grignon, Marie-Noëlle 12 1900 (has links)
On note un taux élevé de résistance aux traitements dans la leucémie myéloïde aiguë (LMA). Cette résistance peut être associée aux altérations de TP53. Les « ubiquitin specific peptidases » (USP) sont impliquées dans plusieurs cancers mais leurs rôles ne sont pas élucidés dans les LMA. L’analyse de l’expression génique par RT-PCR quantitative de 21 USP et des gènes de l’axe USP7-MDM2-TP53-CDKN1A dans 111 échantillons de LMA a montré une dérégulation de USP44, USP1, USP28 et CDKN1A dans respectivement 72%, 44%, 25% et 42% des cas. CDKN1A, une cible importante de TP53, pourrait avoir un rôle dans la résistance au traitement. Nous avons développé un modèle expérimental pour évaluer la réponse des cellules leucémiques à la doxorubicine et au nutlin 3, un modulateur non génotoxique de TP53, selon l’expression initiale de CDKN1A. Ce travail préliminaire suggère que certains membres de la famille des USP et CDKN1A pourraient représenter de nouvelles cibles thérapeutiques dans les LMA. / There is a high rate of drug resistance in acute myeloid leukemia (AML) which may be associated with TP53 alterations. The « Ubiquitin specific peptidases » (USP) are involved in several cancers but their roles in AML are not elucidated. Gene expression analysis of 21 USP and genes of the USP7-MDM2-TP53-CDKN1A axis by quantitative RT-PCR in 111 AML samples, showed a deregulation of USP44, USP1, USP28 and CDKN1A in respectively 72%, 44%, 25% and 42% of cases. CDKN1A, an important TP53 target, may have a role in treatment resistance. We have developed an experimental model to assess the response of leukemic cells to doxorubicin and nutlin 3, a non genotoxic TP53 modulator, in relation to the CDKN1A expression level. This preliminary work suggests that some members of the USP family and CDKN1A could represent novel therapeutic targets in AML.
66

Déterminants protéiques de la voie de sécrétion Sec impliqués dans la formation de biofilm chez Listeria monocytogenes

Renier, Sandra 07 December 2012 (has links) (PDF)
Listeria monocytogenes est une bactérie pathogène impliquée dans la toxi-infection alimentaire à l'origine de la listeriose, une maladie peu fréquente mais avec un taux de mortalité de 25 % chez l'homme. Cette bactérie est capable de former un biofilm lui permettant de mieux résister aux stress environnementaux ainsi qu'aux traitements de décontamination. Une nouvelle stratégie d'analyse génomique a été développée et a permis de cibler des systèmes de sécrétion et des protéines potentiellement impliqués dans la formation de biofilm. L'inactivation de la voie SecA2 entraîne la formation d'un biofilm aérien et par conséquent fragile. Ce morphotype est capable de croître de façon sessile à 20°C sur du polystyrène alors que ce n'est pas le cas pour la souche sauvage. De nouvelles protéines sécrétées de façon SecA2 dépendante ont été identifiées par l'étude de l'exoprotéome du mutant ΔsecA2 en comparaison avec celui de la souche sauvage. Le rôle des lipoprotéines dans la formation de biofilm ainsi que leur maturation par les peptidases signal de type II, LspA et LspB, a également été abordé. La combinaison d'une analyse de l'expression des gènes codant les lipoprotéines au cours de la formation de biofilm avec l'analyse génomique basé sur le sécrétome a permis de cibler trois lipoprotéines, dont LpeA qui serait impliquée dans les phases tardives de formation de biofilm. Enfin, l'importance majeure de LspA dans la maturation des lipoprotéines, a été mise en évidence par l'étude de l'exoprotéome des doubles mutant ΔlgtΔlspA et ΔlgtΔlspB en comparaison avec celui de Δlgt.
67

Les sérines protéases de la coagulation et leurs récepteurs "proteases-activated receptors": étude analytique de leur signalisation calcium dans une lignée endothéliale et les ostéoblastes

Daubie, Valéry 10 January 2008 (has links)
Des résultats d’expériences cliniques de reconstruction de l’os maxillaire faites à partir de la greffe d’une "pâte osseuse" gélifiée par l’ajout de facteur tissulaire ont été le primum movens de ce travail. Cette "pâte osseuse", faite d’os en poudre et de plasma enrichi en plaquette (PRP) à laquelle on ajoute du facteur tissulaire, est un modèle à la fois de la coagulation et de la régénération osseuse.<p>Pour analyser des effets de la coagulation, nous avons utilisé un modèle connu :la culture primaire de cellules endothéliales (HUVEC). Les effets in vitro des facteurs de coagulation, dénommés protéases de la coagulation, pris séparément, ont été bien étudiés dans ces cellules, néanmoins aucune information sur l’effet combiné de ces protéases ou du plasma en coagulation n’était connue. Nous avons mesuré la "signalisation calcium" comme réponse cellulaire aux différents agents et ces mesures de la signalisation calcium ont été complétées par la mesure d’une autre réponse biologique, à savoir la sécrétion de cytokines pro-inflammatoires (IL-6 et IL-8). Pour l’étude de la régénération osseuse, la signalisation calcium a été mesurée sur une lignée d’ostéosarcomes humains (SaOS-2), stimulée par des protéases de la voie extrinsèque de la coagulation (facteur VIIa, facteur Xa et thrombine). Comme réponse biologique complémentaire, nous avons évalué l’effet des protéases d’intérêt sur l’apoptose induite par l’absence de sérum dans le milieu de culture.<p>\ / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished
68

Etude de l'expression, de la production et de la dégradation de la ghréline / Study of expression, production, and degradation of ghrelin

De Vriese, Carine 23 June 2006 (has links)
La ghréline est un peptide de 28 acides aminés, produit principalement par l’estomac et caractérisé par la présence d’un groupement octanoyl sur la sérine en position 3 (Kojima et al. 1999). La ghréline stimule la libération de l’hormone de croissance (GH) et régule la prise alimentaire et le métabolisme énergétique (Gualillo et al. 2003). Ces activités biologiques sont principalement médiées par le « growth hormone secretagogue receptor » (GHS-R). Deux sous-types de GHS-R, produits par épissage alternatif d’un même gène, ont été clonés :le GHS-R 1a, dont l’activation entraîne une libération de calcium via la formation d’inositol 1,4,5-trisphosphate (IP3), et le GHS-R 1b, qui ne semble pas lié à une activité biologique (Howard et al. 1996). <p>La première partie de mon travail de thèse consistait en l’étude de la dégradation de la ghréline. La ghréline circule dans le sang principalement sous forme de des-acyl ghréline, une forme de ghréline dépourvue du groupement octanoyl qui ne se lie pas au GHS-R 1a. Peu d’études ont été réalisées sur le catabolisme de la ghréline. Les enzymes impliquées dans la dégradation de la ghréline étant des régulateurs importants de son activité biologique, le but de cette étude était d’identifier les sites de clivage et les enzymes impliquées dans la dégradation de la ghréline par du sérum, des sous-fractions plasmatiques et des homogénats de tissus. Nous avons montré qu’au contact de sérum humain et de rat, la ghréline est désoctanoylée, sans protéolyse. Dans le sérum humain, nous avons montré que la butyrylcholinestérase et la « platelet-activating factor acetylhydrolase » (PAF-AH), une phospholipase associée aux lipoprotéines de basse densité (LDL), sont impliquées dans ce phénomène (articles n°1 et n°2). En parallèle, nous avons montré que la ghréline peut être transportée dans la circulation sanguine par les lipoprotéines riches en triglycérides (TRL), les LDL, et les lipoprotéines de haute et de très haute densité (HDL et VHDL) (article n°2). Dans le sérum de rat, la désoctanoylation de la ghréline implique une carboxylestérase (article n°1). Au contact d’homogénats de tissus, la ghréline est dégradée à la fois par désoctanoylation et protéolyse N-terminale, suggérant la participation d’estérases et d’aminopeptidases. Nous avons identifié cinq sites de clivage dans la ghréline :entre les résidus Ser2-(acyl)Ser3 (dans l’estomac et le foie), (acyl ?)Ser3-Phe4 (dans l’estomac, le foie et le rein), Phe4-Leu5 (dans l’estomac et le rein), Leu5-Ser6 et Pro7-Glu8 (dans le rein) (article n°1). <p>La deuxième partie de mon travail de thèse consistait à étudier l’expression et la production de ghréline par différentes lignées leucémiques (HEL, HL-60, THP-1, SupT1), par des leucocytes poly- et mononucléés et par des plaquettes sanguines, et à étudier l’effet de la ghréline sur la prolifération cellulaire. Pour cela, nous avons mis au point des dosages radioimmunologiques (RIA) permettant de quantifier et de distinguer les formes octanoylées et non octanoylées de la ghréline, et nous avons caractérisé en détail les anticorps SB801 et SB969 obtenus. Par HPLC en phase inverse suivie des RIAs, nous avons mis en évidence la présence de ghrélines octanoylée et non octanoylée dans chaque population de cellules. Plus de 80 % de la ghréline produite est octanoylée dans les cellules HEL, les leucocytes et les plaquettes. Nous avons montré que la ghréline endogène stimule la prolifération des cellules HEL de façon autocrine impliquant un récepteur encore non identifié, distinct du GHS-R 1a (article n°3). La ghréline et la des-acyl ghréline inhibent la prolifération des leucocytes mononucléés mais sont dépourvues d’effet sur les cellules HL-60, THP-1 et SupT1. Malgré la présence du GHS-R 1a dans les leucocytes mononucléés, cet effet pourrait être médié par un récepteur différent puisque la des-acyl ghréline exerce le même effet que la ghréline sur la prolifération (article n°4). <p><p><p> / Doctorat en sciences pharmaceutiques / info:eu-repo/semantics/nonPublished
69

Estudo do mecanismo de inibição de cisteína proteases por selenuranas : um modelo quântico, clássico e híbrido

Silva, Gabriela Dias da January 2018 (has links)
Orientador: Prof. Dr. Maurício Domingues Coutinho Neto / Coorientador: Prof. Dr. Rodrigo Luiz Oliveira Rodrigues Cunha / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia/Química, Santo André, 2018. / Recentemente completaram-se dois séculos da descoberta do selênio, um elemento controverso que pode ser considerado tóxico e ao mesmo tempo essencial. Apesar de suas propriedades antagônicas, compostos de selênio possuem um grande apelo biológico desde o relato de sua incorporação em enzimas, através da selenocisteína. Neste contexto, os compostos de selênio e telúrio tem se destacado devido às suas propriedades anti-inflamatória, antioxidante, antiviral e antimicrobiana. E portanto, como potenciais quimioterápicos contra doenças cardiovasculares, infecciosas, neurológicas e parasitárias. Esses compostos também tem se mostrado promissores na inibição de cisteína-catepsinas. Essas enzimas são ubíquas e participam de diversas funções no organismo humano. Porém, a atividade desregulada de cisteína proteases está relacionada com o desenvolvimento de diversas patologias, que as fazem importantes alvos terapêuticos no planejamento de novos fármacos. Ensaios experimentais com calcogenuranas mostraram bons resultados na inibição de cisteína proteases. Embora o mecanismo de reação desses compostos ainda não tenha sido completamente esclarecido, a literatura propõe que a inibição ocorre através da reação de troca de ligante entre o grupo tiol e o átomo de calcogênio em sua forma hipervalente. Nesta abordagem, cálculos de mecânica quântica foram utilizados para a investigação do mecanismo de reação através da análise da energia livre de Gibbs envolvida em trocas de ligantes, utilizando a teoria do funcional de densidade (DFT), com o funcional B3LYP e base 6311-G+(d), considerando efeitos de dispersão e correção de ponto zero. Cálculos híbridos com metodologia quântica acoplada à dinâmica molecular (Quantum Mechanics / Molecular mechanics - QM/MM) foram desenvolvidos para avaliar a energia envolvida na inibição de papaína por selenurana utilizando o software AMBER em interface com o software Orca. Para a dinâmica molecular utilizou-se o campo de força geral do Amber (General Amber Force Field - GAFF) e o modelo de solvatação explícita TIP3P, enquanto que a os cálculos quânticos usaram abordagem semi-empírica com o funcional PM3 e teoria do funcional da densidade com o funcional BLYP e base def2-SV(P) incluindo efeitos de dispersão. Ensaios de docking molecular também foram realizados para determinar uma configuração de atracamento inicial para os cálculos de QM/MM. Os resultados propõem que as reações de troca de ligante ocorrem em duas etapas distintas, dependentes da acidez do meio. As selenuranas dicloradas eliminam cloro, em meio aquoso, e formam espécies tricoordenadas (DMeSeO, DMeOH+, DMeSH+, DMeCl+) que podem interagir com tiolato provinente de cisteína proteases provocando sua inibição em ambientes ácidos, com barreiras de energia muito pequenas (menor que 3 kcal) ou inexistentes. / Recently two centuries of the discovery of selenium have been completed, a controversial element that can be considered toxic and at the same time essential. Despite their antagonistic properties, selenium compounds have a great biological appeal since the report of their incorporation into enzymes, through selenocysteine. In this context, selenium and tellurium compounds have been prominent due to their anti-inflammatory, antioxidant, antiviral and antimicrobial properties. And therefore, as potential chemotherapeutics against cardiovascular, infectious, neurological and parasitic diseases. These compounds have also been shown to be promising in cysteine-cathepsin inhibition. These enzymes are ubiquitous and participate in various functions in the human body. However, the unregulated activity of cysteine proteases is related to the development of several pathologies, which make them important therapeutic targets in the planning of new drugs. Experimental trials with calcogenurans showed good inhibition of cysteine proteases. Although the mechanism of reaction of these compounds has not yet been fully elucidated, the literature proposes that inhibition occurs through the bound between the thiol group and the calcogen atom in its hypervalent form. In this approach, quantum mechanics calculations were used to investigate the reaction mechanism through the Gibbs free energy analysis involved to ligand exchanges reactions, using for this the density functional theory (DFT) with the B3LYP functional and base 6311-G+(d), considering dispersion effects and zero point correction. Hybrid calculations with Quantum Mechanics/Molecular Mechanics (QM/MM) were developed to evaluate the energy involved in the inhibition of papain by selenuran using AMBER software in interface with Orca software. For the molecular dynamics, the general Amber force field (GAFF) and the explicit solvation model TIP3P were used, while the quantum calculations used a semi-empirical approach with the PM3 functional and the DFT with the functional BLYP and base def2-SV (P) including dispersion effects. Molecular docking assays were also performed to determine an initial docking configuration for the QM/MM calculations. The results suggest that the ligand exchange reactions occur in two distinct steps, depending on the acidity of the medium. The dichlorinated selenuranes eliminate chlorine in aqueous medium and form tricoordinated species (DMeSeO, DMeSeOH+, DMeSeSH+, DMeSeCl+) which can interact with thiolate from cysteine proteases causing their inhibition in acid environments, with very small energy barriers (less than 3 kcal) or nonexistent.
70

Clinical value of protein expression of kallikrein-related peptidase 7 (KLK7) in ovarian cancer

Dorn, Julia, Gkazepis, Apostolos, Kotzsch, Matthias, Kremer, Marcus, Propping, Corinna, Mayer, Katharina, Mengele, Karin, Diamandis, Eleftherios P., Kiechle, Marion, Magdolen, Viktor, Schmitt, Manfred 23 June 2020 (has links)
Expression of the kallikrein-related peptidase 7 (KLK7) is dysregulated in ovarian cancer. We assessed KLK7 expression by ELISA and quantitative immunohistochemistry and analyzed its association with clinicopathological parameters and patients’ outcome. KLK7 antigen concentrations were determined in tumor tissue extracts of 98 ovarian cancer patients by ELISA. For analysis of KLK7 immunoexpression in ovarian cancer tissue microarrays, a manual quantitative scoring system as well as a software tool for quantitative high-throughput automated image analysis was used. In immunohistochemical analyses, expression levels of KLK7 were not associated with patients’ outcome. However, in multivariate analyses, KLK7 antigen levels in tumor tissue extracts were significantly associated with both overall and progression-free survival: ovarian cancer patients with high KLK7 levels had a significantly, 2-fold lower risk of death [hazard ratio (HR) = 0.51, 95% confidence interval (CI) = 0.29–0.90, ρ = 0.019] or relapse [HR = 0.47, 95% CI = 0.25–0.91, ρ = 0.024), as compared with patients who displayed low KLK7 levels. Our results indicate that – in contrast to earlier findings – high KLK7 antigen levels in tumor tissue extracts may be associated with a better prognosis of ovarian cancer patients.

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