绿色木霉纤维素酶分子侧链构象与侧链环境特征的研究  

Structural Conformation and Environment of the Side-chain in CellobiohydrolaseⅡMolecule from Trichoderma viride

作　　者：余多慰[1] 袁生[1] 

机构地区：[1]南京师范大学生命科学学院,江苏南京210097

出　　处：《分析测试学报》2004年第5期63-66,共4页Journal of Instrumental Analysis

基　　金：国家自然科学基金资助项目 (30170005) ;江苏省高校自然科学基金资助项目 (03KJB180064)

摘　　要：运用拉曼光谱分析技术能够揭示蛋白质分子基团振动特征 ,本文对绿色木霉 (Trichodermaviride)纤维素酶中的CBHⅡ在固态以及两种 pH值的液态中酶分子的侧链构象与侧链环境状态进行了拉曼分析。结果揭示了CBHⅡ中胱氨酸的CαCβ—S—S′—Cβ′Cα′基团和C—S键 ,蛋氨酸 (甲硫氨酸 )的CαCβ—Cγ—SC基团 ,HCβ—CγS基团和C—S键 ,以及半胱氨酸的HCβ—CγS基团和C—S键的构象特征。实验还证明14个色氨酸是部分暴露的 ,C2—C3—Cβ—Cα 侧链的扭转角[χ2.1]形式多样。在 pH6.0和固体样品中 ,酶蛋白中酪氨酸均为强氢键供体 ,两种样品各有20.3 %、25.1 %是暴露于溶剂的。而pH8.0水溶液中酪氨酸酚羟基成键能力特点是既可做氢键供体 ,又可做氢键受体 ,它们有80By using laser Raman spectroscopy,the structural conformation and environment of the side_ chains of CellobiohydrolaseⅡ(CBHⅡ)molecule from Trichoderma viride were studied both in aqueous solutions(pH6.0and pH8.0)and in the solid state.The results reveal the conformational characterisˉtics of the disulfide-bridge C α C β —S—S′—C β ′C α ′and the C—S bond in cysteine residues,the C α C β —C γ —SC,HC β —C γ S groups and the C—S bond in methionine residues,as well as the HC β —C γ S group and the C—S bond in cysteine residues.The14tryptophan(Trp)residues were found to be partly exposed to solvent,and the C 2 —C 3 —C β —C α side_chain torsion angles[χ 2.1 ]in the molecule are variable.The I 1360 /I 1340 Raman relative intensity ratio suggests that side_chains of the Trp residues are hydrophilic.The tyrosine(Typ)residues were found to be strong proton donors in all three samples.In the pH6.0solution and in the solid sample,only20.3%and25.1%of the total Typ residues are exˉposed to solvent,respectively.In the pH8.0solution,however,nearly80%of the Typ residues are exˉposed,because the phenolic hydroxyl groups behave both as proton donor and acceptor.

关 键 词：绿色木霉 纤维素酶 CBHⅡ 构象 拉曼光谱 

分 类 号：O657.37[理学—分析化学] Q55[理学—化学]