Aspergillus ficuum菊粉酶的荧光光谱研究

以Trp 为荧光探针，测定Aspergillus ficuum 产内切菊粉酶和外切菊粉酶的内源荧光性质，结果表明，外切菊粉酶和内切菊粉酶荧光产生贡献的色氨酸残基可能位于一个极性环境中，内切菊粉酶的色氨酸残基所处环境的极性比外切菊粉酶的色氨酸残基所处的环境极性大。菊粉酶经N- 溴代琥珀酰亚胺(NBS)修饰后，内切菊粉酶荧光发射峰位出现了明显的蓝移，表明内切菊粉酶分子的色氨酸比外切菊粉酶分子的色氨酸对环境的变化更敏感。以丙烯酰胺作为荧光淬灭剂，内切菊粉酶色氨酸的可及分数比外切菊粉酶色氨酸的可及分数大，说明内切菊粉酶分子中的色氨酸比外切菊粉酶的更加暴露。菊粉酶在不同的pH 值环境中荧光强度的变化结果显示：随着环境pH 值的降低，内切菊粉酶的荧光淬灭程度比外切菊粉酶大，表明内切酶分子中色氨酸的微环境对pH 值的变化更敏感。荧光光谱分析揭示了内切菊粉酶和外切菊粉酶具有不同的构象。

Intrinsic Fluorescence of Aspergillus ficuum Inulinases

The intrinsic fluorescence of endo- and exo-inulinase from Aspergillus ficuum was studied by using Trp as the probe. The result indicated that the Trp of endo-inulinase was located in a more polar environment than exo-inulinase. The fluorescence intensity of endo-inulinase was changed more than exo-inulinase by NBS, which suggested that the Trp of endo-inulinase was more sensitive to the change of environment than that of exo-inulinase. The quenching of the Trp fluorescence of inulinase by acrylamide showed that the Trp of endo-inulinase was more accessible than that of exo-inulinase, which displayed the greater exposure of Trp in endo-inulinase than exo-inulinase. With pH value of the environment reducing from 8.0 to 3.5, the fluorescence intensity of endo-inulinase were quenched higher than that of exo-inulinase. The data suggested that the microenvironments of Trp residue in endo-inulinase was more sensitive to the change of pH value than that in exo-inulinase.