番茄凝集素荧光光谱学研究

Study on the Optical Properties of A Lectin from Lycopersicon esculentum Mill.

用内源荧光测定和不带电荷的极性淬灭剂丙烯酰胺以及带电荷的I-离子、Cs+对番茄凝集素内源荧光进行淬灭研究,以揭示凝集素与小分子物质相互作用以及凝集素荧光生色基团的分布情况。结果表明,天然番茄凝集素在280nm和295nm激发时均显示λmax为332nm的荧光发射光谱,表明凝集素荧光生色基团位于相对疏水的环境中;中性淬灭剂丙烯酰胺对凝集素分子的荧光生色基团Trp残基的可接近程度为93.41%,而对阳离子淬灭剂Cs+离子的可接近程度为57.14%,阴离子淬灭剂不能淬灭凝集素的内源荧光,表明番茄凝集素荧光氨基酸残基约43%位于分子内部的疏水核心,57%位于分子近表面的疏水袋中,且氨基酸残基周围有大量的碱性氨基酸分布。

The effects of quenchers on the micro-environment and conformation of Lycopersicon esculentum Mill. lectin （LEL） were studied by fluorescence and quenching of intrinsic fluorescence analysis. The results showed that Native LEL exhibited fluorescence emission was maximum （λmax） at 332 nm upon excitation at both 280 nm and 295 nm, indicating the presence of tryptophan in a relatively hydrophobic region. Fluorescence quenching showed that acrylamide and CsCl were able to quench 93,41% and 57.14 % of the intrinsic fluorescence of LEL, respectively. The extent of quenching was observed high with acrylamide, medium with CsCl and KI didn＇t quench the intrinsic fluorescence of LEL, further supporting that tryptophan residues were mainly buried in a highly hydrophobic region of LEL.