| Summary: | 碩士 === 國立清華大學 === 生物資訊與結構生物研究所 === 101 === Drosophila fatty acid binding protein isoform B (dFABP) is a member of the fatty acid-binding protein family which can bind and transport hydrophobic ligand. dFABP has the high sequence similarity to mammalian brain-type FABP (FABP7) and has been reported to be involved in the enhancement of long-term memory (LTM) consolidation in Drosophila melanogaster. However, the lipid binding specificities or the cellular mechanism processes of LTM consolidation mediated by dFABP are still unclear. In this study, we attempt to characterize its structural properties and to investigate the biological functions of dFabp. The circular dichroism (CD) and one-dimensional nuclear magnetic resonance (NMR) implied that dFabp shows secondary structure of major β-strand conformation and forms a well-packed solution structure. CD spectra also demonstrate that the stability of structure is sensitive to pH value. According to ANS competitive experiment, dFabp has a dominant binding preference for unsaturated than saturated fatty acids. Furthermore, the structural modeling of dFabp/DHA and dFabp/OA complexes analysis and site-directed mutagenesis experiments both revealed that Tyr126 and Arg124 play important roles in ligand binding. Based on the homology sequence alignments and the surface electric analysis of model, we categorize dFABP into group iv which can fold fatty acid in U-shaped conformation or in a highly bent, and also into the
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collision-mediated mechanism of lipid transfer. After all, we gain more insights into the fatty acid binding affinities and the structural properties of dFABP for future studies of long-term memory consolidation.
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