• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 561
  • 390
  • 107
  • 56
  • 29
  • 21
  • 10
  • 10
  • 10
  • 10
  • 10
  • 10
  • 10
  • 9
  • 8
  • Tagged with
  • 1447
  • 412
  • 339
  • 127
  • 126
  • 116
  • 114
  • 108
  • 89
  • 87
  • 85
  • 84
  • 81
  • 80
  • 78
  • 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.
281

Autoantibodies and genetic variation in rheumatoid arthritis : aspects on susceptibility and disease course /

Kastbom, Alf, January 2007 (has links)
Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 5 uppsatser.
282

Structural, functional and energetic analysis of antibodies in complex with staphylococcal nuclease /

Perdue, Samuel Scott. January 1997 (has links)
Thesis (Ph. D.)--University of Virginia, 1997. / Spine title: Protein antigen-antibody complexes. Includes bibliographical references (198-223). Also available online through Digital Dissertations.
283

Designing immunogens to elicit broadly reactive neutralizing antibodies to the HIV envelope /

Derby, Nina Rafterman, January 2007 (has links)
Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 155-209).
284

Desenvolvimento farmacotécnico de um radioimunoconjugado para terapia de linfoma não-Hodgkin / Pharmacotechnical development of a radioimmunoconjugate for non-Hodgkin Lymphoma therapy

MASSICANO, ADRIANA V.F. 22 June 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T14:36:15Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T14:36:15Z (GMT). No. of bitstreams: 0 / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
285

Obtenção e estudo das propriedades de hibridomas produtores de anticorpos monoclonais anti-IL6 humana / Obtainment and study of properties of hybridomas producing anti-IL6 monocional antibody

Scuro, Loren Semionatto 11 November 2005 (has links)
Orientador: Wirla Maria da Silva Cunha Tamashiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-05T10:09:32Z (GMT). No. of bitstreams: 1 Scuro_LorenSemionatto_M.pdf: 980651 bytes, checksum: f54e323b2050cb528e7e829af26086ad (MD5) Previous issue date: 2005 / Resumo: O objetivo do presente trabalho foi a obtenção e caracterização de anticorpos monoclonais contra a IL6 humana recombinante (hr) para serem empregados em ensaios imunoenzimáticos do tipo ELISA (Enzyme linked immunosorbent assay) de detecção da IL6 humana nativa, presente em fluídos biológicos de pacientes portadores de quadros onde os níveis de IL6 encontram-se elevados, ou então produzida por monócitos humanos e murinos ativados in vitro. Dois grupos de hibridomas (1A6 e 3B1) secretores de anticorpos monoclonais anti-IL6 foram obtidos pela fusão de células de mieloma da linhagem SP2 Ag14/0 com esplenócitos de camundongos BALB/c, previamente imunizados com a IL6 humana recombinante. Esses hibridomas foram selecionados com base em sua reatividade com a hrIL6, através de ensaios do tipo ELISA indireto. As imunoglobulinas (Igs) monoclonais produzidas pelos hibridomas dos dois grupos são do isotipo IgG1 Kappa e foram purificadas de líquidos ascíticos e dos sobrenadantes de cultura por cromatografia de afinidade. As proteínas purificadas foram conjugadas com biotina para uso em ensaios de ELISA de captura da hrIL6, de modo a se identificar um ou mais pares de anticorpos adequados a esse tipo de teste, bem como para definir a sensibilidade de detecção da citocina. O par de anticorpos monoclonais 3B1E4 x 1A6F10-biotinilado se mostrou mais promissor nos ensaios de ELISA, detectando a citocina recombinante entre 8 e 512 ng/mL, liberando densidades óticas mais elevadas. Todos os anticorpos monoclonais (AcMos) anti IL6 estudados foram capazes de neutralizar a atividade biológica da citocina em ensaios empregando o hibridoma B13.9, uma célula dependente de IL-6 para seu crescimento. Finalmente, o par de hibridomas anti IL6 3B1E4 e 1A6F10 foi estudado quanto às suas principais características de cultivo: crescimento, produção in vitro dos anticorpos, consumo de glicose e produção de lactato e amônia. O seqüênciamento da porção N-terminal do par 3B1E4 e 1A6F10 revelou que as cadeias leves dos dois anticorpos apresentam seqüência idêntica de aminoácidos. Porém, a análise dos dez resíduos de aminoácidos presentes na região variável das cadeias pesadas resultou em seqüências completamente distintas nos dois monoclonais, sendo um forte indício de diferença nos sítios de ligação ao antígeno dos anticorpos estudados / Abstract: In the present study we have developed monoclonal antibodies against human recombinant (hr) IL6, for the use in ELISA assays to detect the human native IL6 present in biological fluid of patients or in supernatant of activated human and rodent monocytes. Two families of hibridomas (1A6 and 3B1) secreting MAb against-IL6 were obtained from the fusion of mieloma cells from SP2 Ag14/0 lineage with spleen cells from BALB/c mice, previously immunized with human recombinant IL6. Those hibridomas were selected on the basis of their reactivity with the hrIL6, through an ELISA indirect assay. The monoclonal immunoglobulins (Igs) produced by these hibridomas are from IgG1 Kappa isotype and were purified from ascitic fluid and culture supernatant by affinity chromatography. The purified proteins from the ascitic fluid were conjugated with biotin for the use in ELISA hrIL6 capture assay, to identify one or more pairs of antibodies appropriated to this kind of test, as well to define the sensibility of cytokine detection. The pair of MAbs 3B1E4 x 1A6F10-biotinilates was shown promising in ELISA assays, detecting the recombinant cytokine between 8 and 512 ng/mL, liberating elevated optical densities. All of the a-IL6 MAbs studied were capable to neutralize the biological activity of the cytokine in attempt employing the hibridoma B13.9 IL-6 dependent. Finally, the pair of hibridomas a-IL6 3B1E4 and 1A6F10 was studied as regards his main cultivation characteristics: growth, MAb production in vitro, lactate and ammonia production and glucose consumption. The N-Terminal portion sequence of 3B1E4 and 1A6F10 revealed that both light-chains present identical amino acid sequence. However, the analysis of the ten amino acid residues present in variable region of heavy-chains resulted in completely distinct sequences in both antibodies, being a strong indication of difference in their ability to recognize the antigen / Mestrado / Imunologia / Mestre em Genética e Biologia Molecular
286

Desenvolvimento farmacotécnico de um radioimunoconjugado para terapia de linfoma não-Hodgkin / Pharmacotechnical development of a radioimmunoconjugate for non-Hodgkin Lymphoma therapy

MASSICANO, ADRIANA V.F. 22 June 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T14:36:15Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T14:36:15Z (GMT). No. of bitstreams: 0 / A radioimunoterapia tem se mostrado uma modalidade terapêutica promissora, especialmente para terapia de tumores hematológicos o que tem impulsionado o desenvolvimento deste tipo de radiofármaco. Existe hoje apenas um radioimunoconjugado aprovado pelo Food and Drug Administration (FDA), ibritumomabe-tiuxetan-90Y (Zevalin®), e ele apresenta maior taxa de resposta global e de remissão completa quando comparados aos tratamentos convencionais. Entretanto, nenhum deles é comercialmente disponível no Brasil. Neste contexto, o objetivo deste trabalho foi estudar as etapas envolvidas no processo de conjugação e radiomarcação com Lu-177 do anticorpo monoclonal anti-CD20, de forma que fosse possível consolidar nacionalmente a metodologia para desenvolvimento de outros radioimunoconjugados. Nos estudos realizados para determinar a melhor razão molar anticorpo:quelante (DOTA), a razão molar 1:50, apresentou pureza radioquímica elevada (superior a 95%, após a purificação) e imunorreatividade superior a muitos estudos publicados. Além disto, o imunoconjugado apresentou estabilidade de, no mínimo 3 meses, sob refrigeração quando conjugado por dois métodos diferentes. O estudo dos parâmetros de radiomarcação permitiu a obtenção de um radioimunoconjugado com atividade específica de 740 MBq/mg, com estabilidade suficientemente longa que permitirá seu transporte às clínicas médicas. Os perfis de biodistribuição e farmacocinético foram compatíveis com outros radioimunoconjugados encontrados na literatura. O radioimunoconjugado apresentou captação tumoral e estabilidade in vivo apreciáveis, esta última evidenciada pela baixa captação óssea. Realizaram-se estudos de liofilização da formulação aperfeiçoada do imunoconjugado que promoveram a liofilização sem dano estrutural evidenciado por eletroforese em gel de poliacrilamida com manutenção da imunorreatividade. A pureza radioquímica foi acima de 95% (após purificação) quando radiomarcado com atividade específica de 740 MBq/mg, com estabilidade relevante quando armazenado à -20 °C por até 48 horas. Foi possível não somente padronizar as metodologias de conjugação e radiomarcação de anticorpos monoclonais, mas também aprimorá-las de forma que o radioimunoconjugado produzido foi superior em muitos aspectos quando comparado com a literatura publicada. Conclui-se, portanto, que o radioimunoconjugado anti-CD20-DOTA-177Lu é uma ferramenta promissora para o tratamento de tumores linfáticos que expressam o receptor CD20. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
287

"Contribuição ao imunodiagnóstico da leptospirose humana: ênfase ao uso de anticorpos monoclonais" / Contribution to the immunodiagnosis of human leptospirosis: emphasis to monoclonal antibodies.

Maricy Alves Ribeiro 02 December 2003 (has links)
A prova sorológica de referência na leptospirose ainda é a soroaglutinação microscópica (SAM). Devido à complexidade desta prova avaliamos alguns testes rápidos para triagem dos anticorpos anti-leptospiras na fase aguda da infecção. Na década de 80, uma hemaglutinação passiva, utilizando frações polissacarídicas de leptospiras, foi considerada apropriada ao diagnóstico precoce, porém esta preparação antigênica incluía muitos “antígenos comuns” reconhecidos por anticorpos de 4% dos indivíduos normais. Um novo ELISA (enzyme-linked immunosorbent assay) utilizando uma suspensão de antígenos imunodominantes, resistentes à proteinase K, foi padronizado e avaliado quanto ao seu valor diagnóstico. Com 89,9% de sensibilidade e 97,4% de especificidade, esta técnica, referida como PK-ELISA, satisfaz os requisitos necessários para as provas de triagem da leptospirose humana. No entanto, em virtude de alguns reagentes usados nesta preparação antigênica serem importados e muito instáveis, foi proposta a introdução de novos métodos empregando-se anticorpos monoclonais. Em um “Acordo de Pesquisa Cooperativa” entre o Instituto Adolfo Lutz e o Laboratório Fleury foram produzidos hibridomas contra leptospiras. Dois deles foram selecionados para dar continuidade ao estudo: um, secretando anticorpos monoclonais (AcM) para um epítopo detectado em 16 de 23 sorovares do gênero Leptospira mais freqüentes em nosso meio (clone A12P4), e outro específico a somente um sorogrupo patogênico, icterohaemorragiae (clone H7P1). O AcM A12P4, uma imunoglobulina G2B (IgG2B), reagiu com epítopo presente nos componentes de pesos moleculares (PM) de 16-18 kDa dos lisados de leptospiras das cepas RGA e M-20, quando separados na eletroforese em gel de poliacrilamida, e com componentes de PM de 75-84kDa dos sorovares copenhageni e canicola. Por sua vez, o AcM H7P1, uma imunoglobulina G, reagiu com um epítopo comum a várias frações de PM acima de 21 kDa da cepa RGA e com componentes de PM de 21-22 kDa e de 75-82 kDa da cepa M-20. Os monoclonais foram empregados em provas imunoenzimáticas para a detecção de anticorpos específicos em amostras séricas pareadas coletadas de 52 pacientes com leptospirose, e do grupo controle que incluiu amostras séricas de 57 pacientes com outras doenças consideradas no diagnóstico diferencial, e de 68 indivíduos normais. Estas provas, no entanto, não foram satisfatórias. Finalmente, um novo ELISA foi desenvolvido no presente estudo que utiliza a suspensão de antígenos “AgMc”, purificados por cromatografia de afinidade utilizando a Sepharose 4B ativada com CNBr acoplada aos anticorpos monoclonais descritos acima. Os resultados obtidos com esta prova foram comparados aos obtidos com outros testes disponíveis em nosso meio, como a SAM e o ELISA clássico (ELISA c). Este novo método, o “ELISA AgMc”, com 80,70 % e 83,33 % de sensibilidade e especifidade, respectivamente, em relação à SAM; valores preditivos positivo e negativo de 69,70% e 90,10% respectivamente e índice de concordância geral de 82,49%, não parece ser um protocolo promissor para o diagnóstico rápido na leptospirose humana. Além disso, tomando-se a SAM como diagnóstico verdadeiro, os resultados obtidos no novo teste, após a conclusão diagnóstica do grupo de pacientes com a leptospirose, mostrou uma discordância significativa. São discutidas as possíveis explicações para os resultados encontrados. / The best serological test for leptospirosis laboratory diagnosis remains the microscopic agglutination test (MAT). Because of the complexity of MAT, we have been developed some rapid screening tests for leptospiral antibodies detection in the acute phase of infection. In the decade of 80, a passive hemagglutination test employing polysaccharide fractions of leptospires was considered appropriate for early diagnosis, but its antigen preparation included “common antigens” recognized by antibodies from 4% of healthy individuals. A new ELISA (enzyme-linked immunosorbent assay) employing proteinase K resistant immunodominant antigens was developed and its potential diagnosis evaluated. This technique, the PK-ELISA, presented 89.9% sensitivity and 97.4% specificity, and satisfied the requeriments needed for serological screening tests of human leptospirosis. However, some of the reagents used in its antigen preparation are imported and very unstable. So, it was proposed, in a “Cooperative Research Accordance” between Instituto Adolfo Lutz and Laboratório Fleury, to try new approaches with monoclonal antibodies. Two hibridomas secreting specific monoclonal antibodies (MAb) were selected: one, against an epitope detected in 16 of 23 members of the genus Leptospira (clone A12P4) and the other, specific to the icterohaemorragiae serogroup (clone H7P1). The MAb A12P4, a G2 (IgG2B) immunoglobulin, reacted with an epitope present in the 16-18 kDa components of icterohaemorragiae serogroup and with the 75-84 kDa components of serovars copenhageni and canicola, after whole-cell lysates of the leptospires were separated by sodium dodecyl sulfate- polyacrylamide gel electrophoresis. The MAb H7P1, which is an IgG, reacted with an epitope common to several fractions of molecular weight above 21 kDa of strain RGA and with the 21-22 kDa and the 75-82 kDa components of strain M-20. Both monoclonal antibodies were employed in enzyme immunoassays for detecting specific antibodies in serum samples serially colleted from 52 patients with leptospirosis, and from the control group, which consisted of sera from 57 patients with other diseases included in the differential diagnosis, and from 68 healthy individuals. These tests, however, were not satisfactory. A new ELISA was developed in the present study employing an antigen suspension “AgMc”, purified by affinity chromatography with CNBr-activated Sepharose 4B coupled to the monoclonal antibodies described above. The results obtained with this test were compared to the MAT and to the classical IgM ELISA (ELISA c). The new method, “AgMc ELISA”, presented serological indices, relatively to reference test MAT, of 80.70 % and 83.33 % of sensitivity and specificity, respectively; positive and negative predictive values of 69.70 % and 90.10 %, respectively, and general agreement index of 82.49 %. So, this test was not considered a promising approach to rapid diagnosis of human leptospirosis. Moreover, the proportion of patients diagnosed as having leptospirosis by the “AgMc ELISA” and the MAT differ significantly. The possible explanations for the results obtained are discussed.
288

Studies of a sperm acrosomal antigen recognized by HS-63 monoclonal antibody

Liu, Ming-Sun January 1991 (has links)
A sperm specific and species conserved monoclonal antibody (HS-63) was shown to inhibit in vitro fertilization of mouse oocytes and human sperm penetration to zona-free hamster ova. The sperm antigen (SA-63) which reacts with HS-63 was found to be localized on the sperm acrosome. Following sperm capacitation, this antigen becomes exposed and is shed after the acrosome reaction. SA-63 may be involved in the sperm acrosome reaction during the initial fertilization process. Sperm antigen (SA-63) from mouse (MSA-63) was purified from mouse testes with soluble and detergent extraction procedures followed by immunoaffinity chromatography. The purified MSA-63 antigen was shown to be a group of proteins with a size ranging from 25 Kd to 50 Kd and pIs of about 4.2 when analyzed by two dimensional gel electrophoresis. MSA-63 antigen may be associated with actins in its native form. A proteolytic activity was found in the solution of purified MSA-63 preparation. Purified MSA-63 was used for immunization of mice and rabbits. Following successive immunizations, antisera of high titres were raised and reacted specifically with sperm acre-some. The isoimmune sera from immunized mice exhibited significant inhibition on in vitro fertilization of mouse oocytes. Complementary deoxyribonucleic acid (cDNA) fragments encoding the MSA-63 were cloned from a mouse testis cDNA library by using an immunoscreening method with rabbit antisera against MSA-63 as the detecting probe. When a specific cDNA probe was used for Northern blot analysis, an mRNA of 1.5 Kb in size was detected only in the adult mouse testis, but not in any other somatic tissues. By Southern blot analysis, it was also demonstrated that the gene encoding for SA-63 protein is conserved among different mammalian species. The location of SA-63 antigen gene was determined to be on human chromosome 11 when analyzed with a blot of a human-hamster somatic cell hybrid panel. By DNA sequence analysis, a protein of 28 Kd in size was deduced from the MSA-63 cDNA. The amino acid sequences of trypsin-digested peptide fragments of MSA-63 were used to verify that deduced amino acid sequence from the cDNA. The recombinant fusion proteins containing MSA-63 protein fragment were produced in E. coli and used to immunize female mice. Similar to the original HS-63 monoclonal antibody, the antisera thus produced reacted only with the sperm acrosome and revealed significant inhibition of the in vitro fertilization of mouse oocytes. In the developing mouse testis, the expression of MSA-63 gene was found to be post-meiotic. Protein and mRNA of MSA-63 were not produced until day 20 after birth. / Medicine, Faculty of / Obstetrics and Gynaecology, Department of / Graduate
289

Occurrence and Structure of an Activating Enzyme for an S6 Kinase Determined by Monoclonal Antibody Analysis

Murdoch, Fern E. (Fern Elizabeth) 05 1900 (has links)
In this study, the production of monoclonal antibodies directed against the activating enzyme for an S6 kinase is examined and described. Evidence is presented for the association of an Mr. 55,000 abd Mr. 95,000 protein with the s6 kinase. These proteins are phosphorylated in the presence of Activating Enzyme. A sequence of regulatory events for insulin-stimulated phosphorylation of ribosomal protein S6 in cells is postulated as follows: insulin activates the receptor tyrosine kinase, which phosphorylates the Mr 116,000 subunit of Activating Enzyme. The Activating Enzyme then activates the S6 kniase by phosphorylation, and phosphorylation of the ribosomal protein s6 is promoted.
290

Versuche zur Gewinnung von katalytischen Antikörpern zur Hydrolyse von Arylcarbamaten und Arylharnstoffen / Attempts to produce catalytic antibodies for hydrolysis of arylcarbamates and arylureas

Werner, Deljana January 2002 (has links)
Im Rahmen dieser Arbeit gelang es, katalytische Antikörper zur Hydrolyse von Benzylphenylcarbamaten sowie zahlreiche monoklonale Antikörper gegen Haptene herzustellen.<br /> <br /> Es wurden verschiedene Hapten-Protein-Konjugate unter Verwendung unterschiedlicher Kopplungsmethoden hergestellt und charakterisiert. Zur Generierung der hydrolytisch aktiven Antikörper wurden Inzuchtmäuse mit KLH-Konjugaten von 4 Übergangszustandsanaloga (ÜZA) immunisiert. Mit Hilfe der Hybridomtechnik wurden verschiedene monoklonale Antikörper gegen diese ÜZA gewonnen. Dabei wurden sowohl verschiedene Immunisierungsschemata als auch verschiedene Inzuchtmausstämme und Fusionstechniken verwendet. Insgesamt wurden 32 monoklonale Antikörper gegen die verwendeten ÜZA selektiert. Diese Antikörper wurden in großen Mengen hergestellt und gereinigt. <br /> <br /> Zum Nachweis der Antikörper-vermittelten Katalyse wurden verschiedene Methoden entwickelt und eingesetzt, darunter immunologische Nachweismethoden mit Anti-Substrat- und Anti-Produkt-Antikörpern und eine photometrische Methode mit Dimethylaminozimtaldehyd. Der Nachweis der hydrolytischen Aktivität gelang mit Hilfe eines Enzymsensors, basierend auf immobilisierter Tyrosinase. Die Antikörper N1-BC1-D11, N1-FA7-C4, N1-FA7-D12 und R3-LG2-F9 hydrolysierten die Benzylphenylcarbamate POCc18, POCc19 und Substanz 27. Der Nachweis der hydrolytischen Aktivität dieser Antikörper gelang auch mit Hilfe der HPLC. <br /> <br /> Der katalytische Antikörper N1-BC1-D11 wurde kinetisch und thermodynamisch untersucht. Es wurde eine Michaelis-Menten-Kinetik mit Km von 210 &#181;M, vmax von 3 mM/min und kcat von 222 min-1 beobachtet. Diese Werte korrelieren mit den Werten der wenigen bekannten Diphenylcarbamat-spaltenden Abzyme. Die Beschleunigungsrate des Antikörpers N1-BC1-D11 betrug 10. Das ÜZA Hei3 hemmte die hydrolytische Aktivität. Dies beweist, dass die Hydrolyse in der Antigenbindungsstelle stattfindet. Weiter wurde zwischen der Antikörperkonzentration und der Umsatzgeschwindigkeit eine lineare Abhängigkeit festgestellt. Die thermodynamische Gleichtgewichtsdissoziationskonstante KD des Abzyms von 2,6 nM zeugt von einer sehr guten Affinität zum ÜZA. <br /> <br /> Hydrolytisch aktiv waren nur Antikörper, die gegen das Übergangszustandsanalogon Hei3 hergestellt worden waren. Es wird vermutet, dass die Hydrolyse der Benzylphenylcarbamate über einen Additions-Eliminierungsmechanismus unter Ausbildung eines tetraedrischen Übergangszustandes verläuft, dessen analoge Verbindung Hei3 ist.<br /> <br /> Im Rahmen der Generierung von Nachweisantikörpern zur Detektion der Substratabnahme bei der Hydrolyse wurden Anti-Diuron-Antikörper hergestellt. Einer der Antikörper (B91-CG5) ist spezifisch für das Herbizid Diuron und hat einen IC50-Wert von 0,19 &#181;g/l und eine untere Nachweisgrenze von 0,04 &#181;g/l. Ein anderer Antikörper (B91-KF5) reagiert kreuz mit einer Palette ähnlicher Herbizide. Mit diesen Antikörpern wurde ein empfindlicher Labortest, der ein Monitoring von Diuron auf Grundlage des durch die Trinkwasserverordnung festgeschriebenen Wertes für Pflanzenschutzmittel von 0,1 &#181;g/l erlaubt, aufgebaut. <br /> <br /> Der Effekt der Anti-Diuron-Antikörper auf die Diuron-inhibierte Photosynthese wurde in vitro und in vivo untersucht. Es wurde nachgewiesen, dass sowohl in isolierten Thylakoiden, als auch in intakten Algen eine Vorinkubation der Anti-Diuron-Antikörper mit Diuron zur Inaktivierung seiner Photosynthese-hemmenden Wirkung führt. Wurde der Elektronentransport in den isolierten Thylakoiden oder in Algen durch Diuron unterbrochen, so führte die Zugabe der Anti-Diuron-Antikörper zur Reaktivierung der Elektronenübertragung. / Attempts to produce catalytic antibodies for hydrolysis of arylcarbamates and arylureas:<br /> The aim of the investigations was to produce antibodies which are able to cleave herbicides resistant to naturally occuring enzymes. Structurally similar carbamate and urea derivatives were chosen for the experiments.<br /> <br /> Phosphonate derivatives were synthesized that mimick possible transition state analogues in structure and charge. Mice were immunized with 4 different derivatives after conjugating them to carrier proteins. 32 hybridomas were established that produce monoclonal antibodies binding to these derivatives. <br /> <br /> The possible cleavage of substrates was determined by immunoassays with monoclonal antibodies against the substrate and the products and with a photometric method based on dimethylaminocinammonaldehyde. The measuring of cleavage products was succeeded by an amperometric method. The enzyme sensor was based on immobilized tyrosinase which oxidizes p-chlorophenol and phenol.<br /> <br /> The antibodies N1-BC1-D11, N1-FA7-C4, N1-FA7-D12 und R3-LG2-F9 hydrolysed the benzylphenylcarbamates POCc18, POCc19 und Substance 27. The hydrolytic activity of these antibodies was also succeeded with HPLC.<br /> <br /> The catalytic antibody N1-BC1-D11 was investigated kinetically and thermodynamically. A Michaelis-Menten-Kinetic was observed (at pH 8.0 exhibited a Km 210 &#181;M, a vmax 3 mM/min and a kcat 222 min-1). These values are in the range of the values obtained for the antibody-catalysed hydrolysis of diphenylcarbamates. The rate enhancement of N1-BC1 was 10. The reaction was completely inhibited by stoichiometric quantities of the transition state analogue Hei3. This is consistent with the affinity of the abzyme to Hei3 of 2.6 nM, determined by BIAcore assay.<br /> <br /> Only antibodies generated against Hei3 showed hydrolytic activity. The hydrolysis of benzylphenylcarbamates presumably occurs via an addition-elimination-Mechanism involving a tetrahedral intermediate. <br /> <br /> In summary, this work presents the first example of antibody-catalysed hydrolysis of benzylphenylcarbamates. <br /> <br /> Monoclonal anti-diuron antibodies were generated that bind to the herbicide diuron with an extremely low equilibrium dissociation constant. A sensitive immunoassay with a low detection limit of 0.2 nM for diuron was established. This is the most sensitive immunological method for detection of diuron known so far.<br /> <br /> These antibodies were also used in vitro and in vivo to prevent diuron-dependent inhibition of photosynthesis or to restore photosynthesis after inhibition. In isolated thylakoids prepared from spinach leaves (Spinacia oleracea L.) the diuron-inhibited Hill reaction was reconstituted immediately following the addition of the monoclonal antibodies. In an in vivo approach the photosynthetic oxygen evolution of the cell wall deficient mutant (cw 15) of the green alga Chlamydomonas reinhardtii Dangeard was monitored. The antibodies prevented the diuron-dependent inhibition of photosynthesis and restored photosynthesis after inhibition. Transgenic plants that synthesize and accumulate these antibodies or antibody fragments and are therefore diuron-resistant can be created.

Page generated in 0.1127 seconds