| Summary: | 碩士 === 長庚大學 === 生物醫學研究所 === 99 === Lectins are carbohydrate binding proteins or glycoproteins, found ubiquitously in plants, animals and microbes. They mediate cell-cell interactions by combining with complementary carbohydrates on opposing cells, playing key roles in the control of various physiological and pathological processes in living organisms, such as fertilization, embryogenesis, cell migration, organ formation, inflammation, immune defense and microbial infection. Pseudomonas aeruginosa is an opportunistic pathogen, belonging to the family Pseudomonadaceae, which can infect animals and human, especially patients suffering from cystic fibrosis, burns and immunodeficiency. Ralstonia solanacearum, another family member, causes wilting in a very wide range of potential host plants. Binding to the host cells is mediated by adhesins, including several related lectins which production is closely regulated in association with virulence factors. Four lectins have been isolated and identified: PA-IL, PA-IIL（of P. aeruginosa）, RSL and RS-IIL（of R. solanacearum）, they are specific to galactose, fucose and mannose, respectively. Two of them（PA-IIL and RSL）are specific to LFuc>DMan, while a few LFuc- specific microbial lectins are found. Due to the weak reactivities of DManα1→ and Galbeta1→4GlcNAcbeta（IIbeta）glycotopes with RSL and PA-IIL, their recognition were ignored. To investigate the mechanism of microbial pathogenesis, we studied the binding properties of lectins and glyco-active sites of complex carbohydrate by enzyme linked lectinosorbent assay. From the results, we found that （1）PA-IIL has only one LFuc recognition site for adopting both LFucα1→ and DManα1→ glycotopes;（2）RSL has two recognition sites for LFuc and DMan glycotopes;（3）polyvalency of IIbeta is essential for both LFucα1→ and DManα1→ combining sites;（4）high density DManα1→ and IIbetacomplex can enhance their recognition. Those informations provide basic knowledge to design new antimicrobial drug.
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