No description available.

Changes in the secondary structure and aggregation of concanavalin A (Con A) were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The secondary structure of Con A has been shown to be affected by factors such as temperature, pH, ionic strength, pressure and the presence of sugars. DSC studies indicated that the thermal stability of Con A is enhanced in the presence of salts, sugars and by pH. Detailed examination of the conformation-sensitive amide I band in the FTIR spectrum of Con A revealed that concentration, sugars, metal ions and pressure (range from 0-14.4 kbar) had no effect on the structural conformation of Con A at room temperature. Variable-temperature FTIR studies of the thermal stability of Con A as a function of pH showed that maximum thermal stability is achieved under alkaline conditions (pH 8-10). It was also found that sugars enhanced the thermal stability of Con A to varying degrees and that the stabilizing effect of the sugar was not dependent on the sugar binding specificity of the lectin.

No description available.

A heterodimeric 60 kDa lectin was isolated from the ground bean ( Vigna sesquipedalis cv ground bean). Its hemagglutinating activity was inhibited by polygalacturonic acid and not by galacturonic acid and other simple monosaccharides. Ground bean lectin exhibited mitogenic activity on murine splenocytes, reduced the viability of hepatoma and leukemia cells, and exerted an inhibitory activity toward HIV-1 reverse transcriptase. / A homodimeric 30-kDa glucose/mannose-specific lectin was purified from emperor banana. In contrast to Con A, the mitogenic activity of emperor banana lectin (EBL) toward mouse splenocytes but not its NO stimulatory effect toward mouse macrophages could be abrogated by 200 mM glucose. It also inhibited proliferation of tumor cells and inhibited HIV-1 reverse transcriptase. / A homodimeric 60-kDa lectin with specificity toward mannose, glucose and rhamnose and substantial N-terminal sequence to Concanavalin A has been isolated from Canavalia gladiata legumes. In contrast to Con A, the mitogenic activity of knife bean lectin toward mouse splenocytes but not its antiproliferative activity toward tumor cells could be abrogated by 200 mM glucose. The lectin inhibited HIV-1 reverse transcriptase, but did not exhibit antifungal activity. / A homotetrameric 120-kDa agglutinin was isolated from haricot bean seeds. It manifested a weaker mitogenic activity than concanavalin A toward mouse splenocytes and exhibited antiproliferative activity toward several tumor cell lines. / A plant defensin-like peptide, with a molecular mass around 6-kDa, was purified from the seeds of Chinese lima beans (Phaseolus lunatus L. ). Phld exerted an antifungal activity and an antibacterial action. Phld could reduce the activity of HIV-1 reverse transcriptase and inhibit translation in a cell-free rabbit reticulocyte lysate system. (Abstract shortened by UMI.) / Defense proteins are produced by a wide range of organisms including mammals, insects, plants, fungi and bacteria. In this study, focus was placed on 2 kinds of defense proteins in plants, namely, lectins/hemagglutinins and defensin-like peptides/defensins. Three lectins, one hemagglutinin (i.e. lectin whose hemagglutinating activity cannot be inhibited by simple saccharides), one defensin and two defensin-like peptides were isolated from 5 species of plants. The isolation procedure included different chromatographic techniques, involving ion exchange chromatography, affinity chromatography and gel filtration. / Wong Ho. / "August 2005." / Adviser: Tzi Bun Ng. / Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3785. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. i-xxvii). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 155-165). Also available on the World Wide Web.

by Luk Choi Wan. / Thesis submitted in: November 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 125-132). / Abstracts in English and Chinese. / Abstract --- p.iv / 摘要 --- p.vi / Acknowledgements --- p.viii / Tabel of contents --- p.x / List of Figures --- p.xii / List of Tables --- p.xiv / List of Abbreviations --- p.xv / List of Abbreviations --- p.xv / Chapter Chapter One --- Literature review --- p.1 / Chapter 1.1 --- General introduction --- p.1 / Chapter 1.2 --- General aspects of plant lectins --- p.4 / Chapter 1.3 --- Monocot mannose-binding lectins --- p.5 / Chapter 1.3.1 --- General introduction --- p.5 / Chapter 1.3.2 --- Sugar specificity --- p.6 / Chapter 1.3.3 --- Isolation and purification --- p.7 / Chapter 1.3.4 --- Molecular cloning --- p.9 / Chapter 1.3.5 --- Molecular structure and modifications --- p.10 / Chapter 1.3.6 --- Molecular evolution --- p.12 / Chapter 1.3.7 --- Transformation --- p.12 / Chapter 1.3.8 --- Physiological roles --- p.14 / Chapter 1.3.9 --- Application --- p.19 / Chapter 1.4 --- Dendrobium nobile --- p.31 / Chapter 1.4.1 --- Background --- p.31 / Chapter 1.4.2 --- Chemical analysis --- p.32 / Chapter Chapter Two --- Biological activities of a mannose-binding lectin isolated from Dendrobium mobile --- p.33 / Chapter 2.1 --- Introduction --- p.33 / Chapter 2.2 --- Materials and methods --- p.35 / Chapter 2.2.1 --- Mannose-binding lectin from D. nobile --- p.35 / Chapter 2.3 --- Biological activities of mannose-binding lectin from D. nobile --- p.36 / Chapter 2.3.1 --- Hemagglutinating activity --- p.36 / Chapter 2.3.2 --- In vitro anti-proliferative assay --- p.37 / Chapter 2.3.3 --- In vitro antiviral assay --- p.40 / Chapter 2.3.4 --- Statistical Analysis --- p.42 / Chapter 2.4 --- Results --- p.43 / Chapter 2.4.1 --- Physiochemical properties of D. nobile lectins --- p.43 / Chapter 2.4.2 --- Cytotoxicity to cancer cell lines --- p.53 / Chapter 2.4.3 --- Antiviral activity --- p.59 / Chapter 2.5 --- Discussion --- p.60 / Chapter Chapter Three --- Molecular cloning of lectin gene of Dendrobium nobile --- p.65 / Chapter 3.1 --- Introduction --- p.65 / Chapter 3.2 --- Methods --- p.67 / Chapter 3.2.1 --- RNA extraction --- p.67 / Chapter 3.2.2 --- RT-PCR synthesis of D. nobile lectin cDNA --- p.68 / Chapter 3.2.3 --- RACE of D. nobile agglutinin gene --- p.69 / Chapter 3.2.4 --- Generation of DNL full-length lectin gene sequence --- p.70 / Chapter 3.2.5 --- Cloning and sequencing of PCR product --- p.71 / Chapter 3.2.6 --- Data analyses --- p.72 / Chapter 3.2.7 --- Synthesis of single-stranded DIG-labeled DNA probe --- p.74 / Chapter 3.2.8 --- Northern blot analysis --- p.74 / Chapter 3.2.9 --- Genomic DNA extraction --- p.75 / Chapter 3.2.10 --- Southern blot analysis --- p.76 / Chapter 3.2.11 --- Expression of DNL in E. coli --- p.76 / Chapter 3.2.12 --- Western blot analysis --- p.78 / Chapter 3.3 --- Results --- p.80 / Chapter 3.3.1 --- Isolation and characterization of DNL gene --- p.80 / Chapter 3.3.2 --- Sequence analysis of DNL --- p.89 / Chapter 3.2.3 --- Secondary and tertiary structure --- p.96 / Chapter 3.2.4 --- Southern blot analysis --- p.99 / Chapter 3.2.5 --- Northern blot analysis --- p.99 / Chapter 3.2.6 --- Expression of fusion protein in E.coli --- p.102 / Chapter 3.4 --- Discussion --- p.104 / Chapter Chapter Four --- General Discussion --- p.110 / Chapter 4.1 --- General discussion --- p.110 / Chapter 4.2 --- Isolation and Characterization of monocot mannose-binding lectin of D. nobile --- p.111 / Chapter 4.3 --- Molecular cloning of monocot mannose-binding lectin of D. nobile --- p.115 / Chapter 4.4 --- Further investigations --- p.122 / Chapter Chapter Five --- Conclusion --- p.124 / References: --- p.125 / Appendix --- p.133

Cheung, Hang Kei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 138-149). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / Table of Contents --- p.vi / List of Abbreviations --- p.x / List of Figures --- p.xi / List of Tables --- p.xiii / Chapter Chapter 1: --- Introduction of Lectins --- p.1 / Chapter 1.1 --- General Introduction --- p.1 / Chapter 1.1.1 --- Definition and History of Lectins --- p.1 / Chapter 1.1.2 --- More than Just Carbohydrate Binding --- p.2 / Chapter 1.1.3 --- Classification of Lectins --- p.3 / Chapter 1.2 --- Plant Lectins --- p.4 / Chapter 1.2.1 --- History of Plant Lectins --- p.4 / Chapter 1.2.2 --- Occurrence of Plant Lectins --- p.5 / Chapter 1.3 --- Physiological Roles of Plant Lectins --- p.6 / Chapter 1.3.1 --- Lectins as Storage Proteins --- p.6 / Chapter 1.3.2 --- Lectins as Defense Proteins --- p.7 / Chapter 1.3.3 --- Lectins as mediator in symbiosis with bacteria --- p.8 / Chapter 1.4 --- Biological Activities of Plant Lectins --- p.9 / Chapter 1.4.1 --- Immunomodulatory Activity --- p.9 / Chapter 1.4.2 --- Lectins and Cancer --- p.10 / Chapter 1.4.3 --- A ntiviral A ctivity --- p.12 / Chapter 1.5 --- Lectins in Glycomic Study --- p.14 / Chapter 1.5.1 --- Background --- p.14 / Chapter 1.5.2 --- Glyco-catch method --- p.15 / Chapter 1.5.3 --- Lectin Blot Analysis --- p.16 / Chapter 1.6 --- Aim of current study --- p.17 / Chapter Chapter 2: --- Purification and Characterization of a Lectin from Musa acuminata --- p.19 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Materials and Methods --- p.20 / Chapter 2.2.1 --- Purification Scheme --- p.20 / Chapter 2.2.2 --- Assay of Hemagglutinating A ctivity --- p.21 / Chapter 2.2.3 --- Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis --- p.22 / Chapter 2.2.4 --- Molecular Mass Determination by FPLC Gel Filtration --- p.22 / Chapter 2.2.5 --- Protein Concentration Determination --- p.22 / Chapter 2.2.6 --- N-terminal amino acid sequence analysis --- p.22 / Chapter 2.2.7 --- Inhibition of Lectin-induced Hemagglutination by Carbohydrates --- p.23 / Chapter 2.2.8 --- Effect of Temperature and pH on Lectin-induced Hemagglutination --- p.23 / Chapter 2.2.9 --- Assay of Mitogenic Activity on Murine Splenocytes --- p.24 / Chapter 2.2.10 --- Assay of Nitric Oxide Production by Murine Peritoneal Macrophages --- p.25 / Chapter 2.2.11 --- Assay of Antiproliferative Activity on Tumor Cell Lines --- p.25 / Chapter 2.2.12 --- Assay of HIV-1 Reverse Transcriptase Inhibitory Activity --- p.26 / Chapter 2.2.13 --- RNA Extraction --- p.27 / Chapter 2.2.14 --- Reverse Transcription: First Strand cDNA Synthesis --- p.28 / Chapter 2.2.15 --- Polymerasae Chain Reaction (PCR) --- p.28 / Chapter 2.3 --- Results --- p.32 / Chapter 2.4 --- Discussion --- p.46 / Chapter Chapter 3: --- Purification and Characterization of a Lectin from Gymnocladus chinensis Baill. --- p.49 / Chapter 3.1 --- Introduction --- p.49 / Chapter 3.2 --- Material and Methods --- p.50 / Chapter 3.2.1 --- Purification Scheme --- p.50 / Chapter 3.2.2 --- Assay of Hemaggl utinating Activity --- p.51 / Chapter 3.2.3 --- Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis --- p.51 / Chapter 3.2.4 --- Molecular Mass Determination by FPLC Gel Filtration --- p.51 / Chapter 3.2.5 --- Protein Concentration Determination --- p.51 / Chapter 3.2.6 --- N-terminal amino acid sequence analysis --- p.52 / Chapter 3.2.7 --- Inhibition of Lectin-induced Hemagglutination by Carbohydrates --- p.52 / Chapter 3.2.8 --- Effect of Temperature and pH on Lectin-induced Hemagglutination --- p.52 / Chapter 3.2.9 --- Assay of Mitogenic Activity on Murine Splenocytes --- p.52 / Chapter 3.2.10 --- Assay of Antiproliferative Activity on Tumor Cell Lines --- p.52 / Chapter 3.2.11 --- Assay of HIV-1 Reverse Transcriptase Inhibitory Activity --- p.53 / Chapter 3.2.12 --- Assay of Anti-fungal Activity --- p.53 / Chapter 3.3 --- Results --- p.56 / Chapter 3.4 --- Discussion --- p.67 / Chapter Chapter 4: --- Introduction to Protease Inhibitors --- p.70 / Chapter 4.1 --- General Introduction --- p.70 / Chapter 4.2 --- Serine Protease Inhibitors --- p.71 / Chapter 4.2.1 --- Kunitz Type Serine Protease Inhibitors --- p.73 / Chapter 4.2.2 --- Bowman-Birk Type Serine Protease Inhibitors (BBI) --- p.74 / Chapter 4.2.3 --- Squash Type Serine Protease Inhibitors --- p.75 / Chapter 4.3 --- Roles of Pis in Plants --- p.76 / Chapter 4.3.1 --- Pis as a defense protein --- p.76 / Chapter 4.3.2 --- Pis in seed germination --- p.78 / Chapter 4.4 --- Applications of Protease Inhibitors --- p.79 / Chapter 4.4.1 --- Pis in Cancer Prevention --- p.79 / Chapter 4.4.2 --- Pis in Crop Protection --- p.81 / Chapter 4.5 --- Aim of Current Study --- p.83 / Chapter Chapter 5: --- Isolation and Characterization of a Trypsin Inhibitor from the seeds of Lens culinaris --- p.84 / Chapter 5.1 --- Introduction --- p.84 / Chapter 5.2 --- Materials and Methods --- p.86 / Chapter 5.2.1 --- Purification Scheme --- p.86 / Chapter 5.2.2 --- Assay of Trypsin-Inhibitory Activity --- p.87 / Chapter 5.2.3 --- Assay of Chymotrypsin-Inhibitory Activity --- p.88 / Chapter 5.2.4 --- Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis --- p.88 / Chapter 5.2.5 --- Molecular Mass Determination by FPLC Gel Filtration --- p.88 / Chapter 5.2.6 --- Protein Concentration Determination --- p.89 / Chapter 5.2.7 --- N-terminal amino acid sequence analysis --- p.89 / Chapter 5.2.8 --- Effect of DTT on the inhibitory activity of trypsin inhibitor --- p.89 / Chapter 5.2.9 --- Assay of Antiproliferative Activity on Tumor Cell Lines --- p.90 / Chapter 5.2.10 --- Assay of HIV-1 Reverse Transcriptase Inhibitory Activity --- p.90 / Chapter 5.2.11 --- Assay of Anti-fungal Activity --- p.90 / Chapter 5.3 --- Results --- p.93 / Chapter 5.4 --- Discussion --- p.103 / Chapter Chapter 6: --- Isolation and Characterization of trypsin inhibitors trom the seeds of Vigna mungo (L.) Hepper --- p.106 / Chapter 6.1 --- Introduction --- p.106 / Chapter 6.2 --- Materials and Methods --- p.107 / Chapter 6.2.1 --- Purification Scheme --- p.107 / Chapter 6.2.2 --- Assay of Trypsin-Inhibitory Activity --- p.109 / Chapter 6.2.3 --- Assay of Chymotrypsin-Inhibitory Activity --- p.109 / Chapter 6.2.4 --- Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis --- p.109 / Chapter 6.2.5 --- Molecular Mass Determination by FPLC Gel Filtration --- p.109 / Chapter 6.2.6 --- Protein Concentration Determination --- p.109 / Chapter 6.2.7 --- N-terminal amino acid sequence analysis --- p.110 / Chapter 6.2.8 --- Effect of DTT on the inhibitory activity of trypsin inhibitor --- p.110 / Chapter 6.2.9 --- Assay of Antiproliferative Activity on Tumor Cell Lines --- p.110 / Chapter 6.2.10 --- Assay of HIV-1 Reverse Transcriptase Inhibitory Activity --- p.110 / Chapter 6.2.11 --- Assay of Anti-fungal Activity --- p.110 / Chapter 6.3 --- Results --- p.113 / Chapter 6.4 --- Discussion --- p.132 / Chapter Chapter 7: --- General Discussion --- p.135 / References --- p.138

Leung, Ho Wai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 136-146). / Abstracts in English and Chinese. / THESIS COMMITTEE --- p.II / ACKNOWLEDGEMENT --- p.III / ABSTRACT --- p.IV / CHINESE ABSTRACT --- p.VI / TABLE OF CONTENT --- p.VII / OVERVIEW OF THIS PROJECT --- p.1 / Chapter SECTION 1: --- Purification and Characterization of hemagglutinins from French bean and mottled kidney bean / Chapter Chapter 1 --- INTRODUCTION / Chapter 1.1 --- General Introduction --- p.2 / Chapter 1.2 --- Physiological functions of plant lectins --- p.6 / Chapter 1.3 --- Physiological functions of animal lectins --- p.9 / Chapter 1.4 --- Biological functions of lectins --- p.12 / Chapter 1.5 --- Clinical and research applications of lectins --- p.16 / Chapter 1.6 --- Legume lectins --- p.17 / Chapter 1.7 --- Isolation and purification of lectins --- p.19 / Chapter 1.8 --- Objectives of the present study --- p.21 / Chapter Chapter 2 --- MATERIALS AND METHODS / Chapter 2.1 --- Chemicals --- p.22 / Chapter 2.2 --- Assay of hemagglutinating activity --- p.24 / Chapter 2.3 --- Purification protocol --- p.26 / Chapter 2.4 --- Assay of saccharide inhibition of hemagglutination --- p.28 / Chapter 2.5 --- Assay of pH stability --- p.28 / Chapter 2.6 --- Molecular mass determination and N-terminal sequence determination --- p.28 / Chapter 2.7 --- Assay of mitogenic activity --- p.29 / Chapter 2.8 --- Assay of antiproliferative activity --- p.30 / Chapter 2.9 --- Assay for antifungal activity --- p.30 / Chapter 2.10 --- Assay of HIV-1 reverse transcriptase inhibitory activity --- p.31 / Chapter 2.11 --- Assay of stability towards trypsin and chymotrypsin --- p.31 / Chapter 2.12 --- Assay of nitric oxide production --- p.32 / Chapter 2.13 --- Assay ofHIV-1 integrase --- p.32 / Chapter Chapter 3 --- EXPERIMENTAL RESULTS / Chapter 3.1 --- Purification scheme --- p.35 / Chapter 3.2 --- Size determination and N-terminal sequencing --- p.36 / Chapter 3.3 --- Temperature stability assay --- p.37 / Chapter 3.4 --- pH stability assay --- p.37 / Chapter 3.5 --- Saccharides inhibition of hemagglutination --- p.37 / Chapter 3.6 --- Stability towards Trypsin and Chymotrypsin --- p.38 / Chapter 3.7 --- Anti-proliferative activity --- p.38 / Chapter 3.8 --- HTV-1 reverse transcriptase inhibition --- p.39 / Chapter 3.9 --- Mitogenic activity --- p.39 / Chapter 3.10 --- Nitric oxide production --- p.39 / Chapter 3.11 --- HIV-1 integrase --- p.39 / Chapter 3.12 --- Defensin --- p.40 / Chapter Chapter 4 --- DISCUSSION / Chapter 4.1 --- Purification scheme --- p.68 / Chapter 4.2 --- Sequence comparison --- p.69 / Chapter 4.3 --- Physical Stability of the hemagglutinins --- p.70 / Chapter 4.4 --- Protease Stability --- p.71 / Chapter 4.5 --- Sugar Specificity Assay --- p.72 / Chapter 4.6 --- Anti-proliferative Aactivity toward Cancer Cells --- p.73 / Chapter 4.7 --- HTV-1 reverse trancriptase and H̐ơþV integrase inhibition --- p.74 / Chapter 4.8 --- Mitogenic activity --- p.75 / Chapter 4.9 --- Antifungal protein --- p.76 / Chapter Chapter 5 --- CONCLUSION --- p.78 / Chapter SECTION 2: --- Purification and Characterization of flammulolysin from mushroom Flαmmulinα velutipes / Chapter Chapter 1 --- INTRODUCTION / Chapter 1.1 --- General Introduction --- p.79 / Chapter 1.2 --- Mechanisms of hemolysis --- p.80 / Chapter 1.3 --- Biological role of hemolysins --- p.80 / Chapter 1.4 --- Mushroom hemolysin --- p.82 / Chapter 1.5 --- Applications of hemolysins --- p.83 / Chapter 1.6 --- Objectives of the present study --- p.83 / Chapter Chapter 2 --- MATERIALS AND METHODS --- p.84 / Chapter Chapter 3 --- EXPERIMENTAL RESULTS / Chapter 3.1 --- Purification and sequence determination --- p.90 / Chapter 3.2 --- Effect of sugars and salts on hemolysin --- p.90 / Chapter 3.3 --- Effect of Temperature and pH on hemolysin --- p.91 / Chapter 3.4 --- Effect of Proteases on hemolysin --- p.91 / Chapter 3.5 --- Effect of osmotic protection on hemolysin --- p.91 / Chapter 3.6 --- Effect of hemolysin on tumor cells --- p.91 / Chapter 3.7 --- Effect of hemolysin on spleen cells --- p.92 / Chapter 3.8 --- Effect of hemolysin on bacterial growth --- p.92 / Chapter 3.9 --- Effect of hemolysin on fungal growth --- p.92 / Chapter Chapter 4 --- DISCUSSION / Chapter 4.1 --- Purification and sequence comparison of hemolysin --- p.103 / Chapter 4.2 --- Sugar and Salts inhibition --- p.104 / Chapter 4.3 --- Temperature stability --- p.105 / Chapter 4.4 --- pH stability --- p.106 / Chapter 4.5 --- Protease stability --- p.106 / Chapter 4.6 --- Osmotic Protection --- p.106 / Chapter 4.7 --- Anti-tumour activity of the hemolysin --- p.107 / Chapter 4.8 --- Anti-fungal activity --- p.108 / Chapter Chapter 5 --- CONCLUSION --- p.109 / Chapter SECTION 3: --- Purification and Characterization of antifungal peptide from buckwheat seeds Fagopyrum esculentum / Chapter Chapter 1 --- INTRODUCTION / Chapter 1.1 --- Plant antiftmgal proteins --- p.110 / Chapter 1.2 --- Classification of antifungal proteins --- p.110 / Chapter 1.3 --- Distribution of antifungal proteins in plants --- p.111 / Chapter 1.4 --- Mechanisms of antifungal activity --- p.111 / Chapter 1.5 --- Future Perspectives of Antifungal proteins --- p.112 / Chapter 1.6 --- Antifungal peptide from Buckwheat --- p.112 / Chapter 1 .7 --- Objectives of the present study --- p.113 / Chapter Chapter 2 --- MATERIALS AND METHODS --- p.114 / Chapter Chapter 3 --- EXPERIMENTAL RESULTS / Chapter 3.1 --- Purification and sequence determination --- p.118 / Chapter 3.2 --- Effect on anti-fungal activity --- p.118 / Chapter 3.3 --- Effect of temperature and pH on antifungal activity --- p.118 / Chapter 3.4 --- Effect of the antifungal peptide on tumor cells --- p.119 / Chapter 3.5 --- Effect of antifungal peptide on HIV-1 Reverse transcriptase Activity --- p.119 / Chapter 3.6 --- Effect of antifungal peptide on spleen cells and NO Production --- p.119 / Chapter Chapter 4 --- DISCUSSION / Chapter 4.1 --- Purification scheme and N-terminal sequence --- p.130 / Chapter 4.2 --- Antifungal Activity --- p.131 / Chapter 4.3 --- Physical stability --- p.131 / Chapter 4.4 --- Anti-proliferative activity toward cancer cells --- p.131 / Chapter 4.5 --- HTV-1 Reverse Transcriptase Inhibitory activity --- p.132 / Chapter 4.6 --- Mitogenic activity and nitric oxide production --- p.132 / Chapter Chapter 5 --- CONCLUSION --- p.133 / OVERALL CONCLUSION --- p.134 / REFERENCES --- p.136

Lectinas estão situadas dentro de um grupo estruturalmente diverso de proteínas que se ligam a carboidratos e glicoconjugados com grande especificidade. Encontradas em diversos organismos, elas são moléculas extremamente úteis na caracterização de sacarídeos, como agentes mediadores de endereçamento de fármacos ou até mesmo como marcadores de superfície celular. A pulchellina é uma glicoproteína heterodimérica ligante de D-Galactose oriunda de sementes de Abrus pulchellus e classificada como proteína inativadora de ribossomo do tipo 2 (“type 2 ribosome-inactivating protein" - type 2 RIP). A cadeia B recombinante da pulchellina (rPBC) foi previamente produzida em E. coli BL21(DE3). Neste presente trabalho, a rPBC é analisada quanto a sua atividade, interação com células de mamíferos “in vitro" e estabilidade estrutural. Os resultados indicam que a rPBC possui seletividade quanto a tipos celulares alvo e é endocitada ativamente, provavelmente compartilhando a via de endocitose descrita para outras RIPs. Além disto, a rPBC foi unida à cadeia catalítica e o heterodímero resultante demonstrou toxicidade similar à da holotoxina nativa, confirmando a atividade da rPBC e atribuindo-lhe papel essencial no mecanismo de intoxicação. Uma segunda parte deste trabalho tratou de outra lectina, extraída de sementes de Camptosema ellipticum. Recentemente, experimentos com extratos aquosos obtidos a partir de sementes de Camptosema ellipticum demonstraram possuir atividade hemaglutinante frente a hemácias humanas. Tal atividade foi atribuída a um dado componente protéico que foi então purificado através de cromatografias de troca iônica e exclusão molecular. A proteína, então chamada camptosemina, demonstrou ocorrer na forma de um tetrâmero e cujo estado de oligomerização pode ser controlado pelo pH do meio. Informações sobre a seqüência primária na porção amino-terminal, obtidas por seqüenciamento de aminoácidos, permitiram o desenho de oligonucleotídeos degenerados para a amplificação e clonagem de seu cDNA. As seqüências dos clones obtidos foram submetidas a diversas rotinas de procura de dados do NCBI. Entre os resultados retornados encontraram-se a concanavalina e a aglutinina de amendoim, dois representantes da chamada família de lectinas de leguminosas. Representantes deste grupo compartilham com a camptosemina o tamanho de seus monômeros e a forma de controle de seus graus de oligomerização. O presente trabalho traz a caracterização preliminar da camptosemina quanto a sua seqüência primária e oligomerização através de técnicas de clonagem e de espectroscopia. Foi possível a clonagem de duas variantes para o cDNA da camptosemina cujas seqüências prevêem um peptídeo sinal N-terminal ausente na proteína madura. As seqüências primárias deduzidas são muito semelhantes entre si e em comparação com outros membros da família de lectinas de leguminosas. A camptosemina se demonstrou extremamente resistente a mudanças de temperatura, exibindo sua dissociação em monômeros somente sob pHs extremamente ácidos ou alcalinos. / Lectins have been placed in a structurally diverse group of proteins that bind carbohydrates and glycoconjugates with high specificity. Found in several organisms, they are extremely useful molecules in the characterization of saccharides, as drug delivery mediators, and even as cellular surface markers. Pulchellin is a D-Galactose-binding heterodimeric glycoprotein from Abrus pulchellus seeds and classified as a type-2 ribosome-inactivating protein (type-2 RIP). The recombinant pulchellin B (rPBC) was previously produced in E. coli BL21 (DE3). In the present work, rPBC is analyzed with respect to its interaction with mammal cells “in vitro" and structural stability. Results show that rPBC has selectivity for targeted cell types and that it is actively endocytosed, probably by the same route described for other RIPs. Furthermore, rPBC was bond to the catalytic chain and the resulting heterodimer has shown toxicity degree very similar to the native holotoxin, confirming rPBC activity and attributing it a essential role in the intoxication mechanism. A second part of this work has dealed with another lectin extracted from the seeds of Camptosema ellipticum. Recently, experiments with water-soluble extracts obtained from the seed of Camptosema ellipticum have shown to have hemagglutinative properties when assayed with human erythrocytes. Such biological activity was attributed to a certain proteic component that was purified by ion-exchange and size-exclusion chromatographies. The protein, so called camptosemin, has shown to occur as a tetramer and which oligomerization’s state could be driven by the environmental pH. Primary sequence information from the amino-terminal portion, obtained by aminoacid sequencing, allowed the design of degenerated oligonucleotides for the amplification and cloning of its cDNA. The obtained clones’ sequences were submitted to several NCBI data bank search scripts. Among the retrieved results were found concanavalin and peanut agglutinin, two representatives of the called legume lectins family. Members of this group share with camptosemin their monomer sizes and the way their oligomerization state can be driven. This present work characterizes camptosemin with respect to its sequence and oligomerization using cloning and spectroscopy techniques. It was possible the cloning of two cDNA variants for camptosemin which sequences deduce an N-terminal signal peptide absent in the mature protein. Deduced primary sequences are very similar to each other and to other legume lectin members. Camptosemin has shown being extremely temperature resistant, only dissociating in monomeric subunits under extremely acid or alkaline pHs.

Yu Yun Lung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 101-114). / Abstracts in English and Chinese. / Acknowledgments / Abstract / Table of Contents / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1 --- General Structure of Lectins --- p.1 / Chapter 1.1.1 --- Metal Binding Sites --- p.2 / Chapter 1.1.2. --- Hydrophobic Sites --- p.3 / Chapter 1.1.3. --- Glycosylation Sites --- p.3 / Chapter 1.2 --- Carbohydrate Specificities of Lectins --- p.4 / Chapter 1.3 --- Plant Lectins --- p.4 / Chapter 1.3.1 --- Localization of lectins in plants --- p.4 / Chapter 1.3.1.1 --- Localization in seeds --- p.4 / Chapter 1.3.1.2 --- Localization in vegetative parts --- p.5 / Chapter 1.3.1.3 --- Biosynthesis of plant lectins --- p.6 / Chapter 1.3.2 --- Functions of plant lectins in plants --- p.7 / Chapter 1.3.2.1 --- In cell growth --- p.7 / Chapter 1.3.2.2 --- In storage --- p.8 / Chapter 1.3.2.3 --- In plant defence --- p.8 / Chapter 1.3.2.4 --- In nitrogen cycle --- p.10 / Chapter 1.3.3 --- Biological activities of plant lectins in other organisms --- p.13 / Chapter 1.3.3.1 --- Immunomodulatory activity --- p.13 / Chapter 1.3.3.2 --- Antitumor and antiproliferative activities --- p.14 / Chapter 1.3.3.3 --- Mitogenic activity --- p.14 / Chapter 1.3.3.4 --- Antiviral activity --- p.14 / Chapter 1.3.4 --- Relationship between lectins and ribosome inactivating proteins: family of ricin-related proteins --- p.16 / Chapter 1.3.5 --- Applications of plant lectins --- p.18 / Chapter 1.3.5.1 --- In scientific research --- p.18 / Chapter 1.3.5.2 --- In medical research --- p.19 / Chapter 1.4 --- Animal Lectins --- p.20 / Chapter 1.4.1 --- Some properties of animal lectins --- p.20 / Chapter 1.4.2 --- Functions of animal lectins --- p.22 / Chapter 1.4.2.1 --- In protein metabolism --- p.22 / Chapter 1.4.2.2 --- As a mediator of binding and phagocytosis of microorganisms --- p.22 / Chapter 1.4.2.3 --- Control of differentiation and organ formation --- p.23 / Chapter 1.4.2.4 --- Lectins and migration of lymphocytes --- p.23 / Chapter 1.4.2.5 --- Lectins and metastasis --- p.24 / Chapter 1.5 --- Mushroom lectins --- p.25 / Chapter 1.6 --- Regulation of lectins --- p.29 / Chapter 1.7 --- Isolation and purification of lectins --- p.31 / Chapter 1.8 --- Objectives of the present study --- p.33 / Chapter CHAPTER 2 --- "SCREENING FOR HEMAGGLUTINATING ACTIVITY IN EXTRACTS OF SEEDS, FRUITS, VEGETABLES AND CHINESE MEDICINAL HERBS" --- p.35 / Chapter 2.1 --- Introduction --- p.35 / Chapter 2.2 --- Materials and methods --- p.36 / Chapter 2.3 --- Results --- p.38 / Chapter 2.4 --- Discussion --- p.38 / Chapter CHAPTER 3 --- ISOLATION OF LECTIN FROM RHIZOMES OF SMILAX GLABRA (FAMILY LILIACEAE) --- p.43 / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.1.1 --- Introduction about Smilax glabra and its chemical constituents --- p.43 / Chapter 3.1.2 --- Introduction about monocot lectins including Liliaceae lectins --- p.45 / Chapter 3.2 --- Materials and methods --- p.50 / Chapter 3.2.1 --- Isolation of lectins from Smilax glabra rhizomes --- p.50 / Chapter 3.2.2 --- Assay for hemagglutinating activity --- p.55 / Chapter 3.2.3 --- Test of inhibition of lectin-induced hemagglutination by various carbohydrates --- p.55 / Chapter 3.2.4 --- "Effects of acid, alkali, temperature and cations on hemagglutinationg activity of lectin" --- p.56 / Chapter 3.2.5 --- Determination of protein concentration --- p.56 / Chapter 3.2.6 --- Molecular mass determination by SDS-PAGE --- p.56 / Chapter 3.2.7 --- Molecular mass determination by gel filtration --- p.56 / Chapter 3.2.8 --- Amino acid sequence analysis --- p.57 / Chapter 3.3 --- Results --- p.57 / Chapter CHAPTER 4 --- ISOLATION OF LECTIN FROM SEEDS OF THE CHINESE CHESTNUT CASTANEA MOLLISIMA (FAMILY FAGACEAE) --- p.74 / Chapter 4.1 --- Introduction to Castanea mollisima and its chemical constituents --- p.74 / Chapter 4.2 --- Materials and Methods --- p.78 / Chapter 4.2.1 --- Isolation of lectin from Chinese chestnuts --- p.78 / Chapter 4.2.2 --- Assay for hemagglutinating activity --- p.83 / Chapter 4.2.3 --- Test of inhibition of lectin-induced hemagglutination by various carbohydrates --- p.83 / Chapter 4.2.4 --- "Effects of acid, alkali, temperature and cations on hemagglutinationg activity of lectin" --- p.83 / Chapter 4.2.5 --- Determination of protein concentration --- p.83 / Chapter 4.2.6 --- Molecular mass determination by SDS-PAGE --- p.83 / Chapter 4.2.7 --- Molecular mass determination by gel filtration --- p.83 / Chapter 4.2.8 --- Amino acid sequence analysis --- p.83 / Chapter 4.3 --- Results --- p.84 / Chapter 4.4 --- Discussion --- p.96 / Chapter CHAPTER 5 --- GENERAL DISCUSSION AND CONCLUSION --- p.98 / REFERENCES: --- p.101