Peptaibols类抗菌肽-Trichokonin Ⅵ在不同溶剂中构象变化的圆二色谱研究

Study on Conformation Transitions of Trichokonin Ⅵ,a Peptaibol-Like Antimicrobial Peptide,in Different Solvents by Circular Dichroism Spectroscopy

TrichoderⅥ是拟康氏木霉SMF2(Trichoderma pseudokoningiiSMF2)产生的一种含有20个氨基酸的peptaibol类抗菌肽。采用圆二色谱法研究了不同极性溶剂体系和膜拟态环境对TrichokoninⅥ的二级结构的影响,TrichokoninⅥ在不同有机溶剂体系中具有典型的螺旋结构特征,而在水溶液体系中螺旋明显减少,不超过30%的三氟乙醇可以随浓度增加而诱导螺旋结构的增加。TrichokoninⅥ在磷酸缓冲液中峰的强度随浓度增加而增强,具有浓度依赖性。SDS浓度的增加可以诱导螺旋含量的增加。与非拟态环境相比,膜拟态环境可以明显增加TrichokoninⅥ的螺旋含量,表明TrichokoninⅥ可以和脂膜相互作用。

Triehokonin Ⅵ, a peptaJboblike antimicrobial peptides isolated from the cultured substrates of trichoderma koningii SMF2, has 20 amino acid residues. The conformational flexibility of trichokonin Ⅵ in organic solvents with different polarities, aqueous solvents and membrane mimic solvents was studied by circular dichroism spectroscopy. Trichokonin Ⅵ takes on a typical a-helical structure in different orgarnc solvents, but helicity decreases in aqueous solvent. The helical content increases with in- creasing the concentration of TFE up to 30%. In phosphate buffered saline, the CD spectrum of trichokonin Ⅵ is concentration dependent, and the intensity of the peaks increases with increasing the concentration of trichokonin Ⅵ. SDS induces a significant transition towards a helix formation, and the CD spectra in membrane mimic solvents increase heticity compared with those recorded without membrane mimic solvents, suggesting the interaction of the peptides with the membrane.