慈菇蛋白酶抑制剂A和B中Trp残基周围构象与酶抑制专一性的关系

通过定点诱变结合荧光光谱学方法研究了慈菇蛋白酶抑制剂A和B(APIA和APIB)Trp残基周围构象与酶抑制专一性之间的关系。研究表明APIB中的两个Trp残基 (93和 12 2位 )所处环境的疏水性要比APIA中的强。Trp定点诱变研究表明 ,在APIB中 ,Trp12 2 周围环境的疏水性要比Trp93 强。用Ser和Leu分别替代 82位Leu和 87位Arg ,使APIB中色氨酸荧光特性变得与APIA的基本相同 ,同时还发现其酶的抑制专一性也变得趋近APIA的 ,暗示Trp周围的构象与酶抑制剂的抑制专一性有关。

Conformation nearby Trp Residues of APIA and APIB Modulates the Inhibitory Specificity of the Protease

The relationship between the micro environment of the two tryptophan residues and the inhibitory specificity of arrowhead protease inhibitors A and B (APIA and APIB) was studied by mutagenesis and fluorescence spectroscopy. The environment of the two Trp residues at positions 93 and 122 in APIB is more hydrophobic than in APIA. Study after substitution of Trp with Ala revealed that the environment of Trp 122 is more hydrophobic than that of Trp 93 . Substitution of Leu 82 and Arg 87 in APIB with Ser and Leu respectively made the tryptophan fluorescence of APIB to be like that of APIA and the inhibitory specificity to be closer to APIA, indicating that the inhibitory specificity of the enzyme may be modulated by the conformation around the tryptophan residues.