| 蜂毒肽与CT-DNA的相互作用 | |
| Interaction of Melittin and Calf Thymus DNA | |
| 摘要: 通过圆二色光谱、紫外光谱、荧光光谱以及等温滴定量热等技术研究了蜂毒肽(Mel)与小牛胸腺DNA (CT-DNA)之间的相互作用以及构象变化。结果表明Mel可以与CT-DNA形成复合物。复合物的形成使得Mel的构象发生变化，由无规卷曲转变为α-helix，Mel中色氨酸残基处于更加疏水的环境。同时，CT-DNA的结构发生变化，解链温度(Tm)从64.3℃增加到66.2℃。Mel与CT-DNA的结合常数(Ka)约为105 L·mol-1，复合物的形成是吸热的过程，主要依靠静电作用，其次是疏水作用。 | |
| 关键词: 蜂毒肽 CT-DNA 构象 复合物 | |
| 基金项目: 国家自然科学基金(No.21571117)、山西省自然科学基金(No.201901D211532)、山西省教育厅基金(No.2020L0416)和山西中医药大学科研基金(No.2020BK09)资助。 | |
| Abstract: The binding of melittin (Mel) to Calf Thymus DNA (CT-DNA) and conformation change were described by circular dichroism (CD) spectra, UV-Vis spectra, fluorescence spectra, and isothermal titration calorimetry (ITC) in 10 mmol·L-1 HEPES buffer (pH=7.4). The results showed that Mel could form a complex with CT-DNA. The formation of the complex changed the conformation of Mel from random coil to α-helix as shown by CD spectra. The red edge excitation shift (REES) studies of tryptophan (Trp) residue in Mel indicated that Trp residue is located in the more hydrophobic environment in the complex with DNA, exactly as demonstrated by fluorescence lifetime and acrylamide experiments. Additionally, the double helix structure of CT-DNA changed and the CT-DNA melting temperature (Tm) increased from 64.3 to 66.2 ℃ once a complex was formed with Mel. Finally, the ITC experiment demonstrated that the binding of Mel to CT-DNA is an endothermic process. The interaction between Mel and CT-DNA was further characterized by an equilibrium association constant (Ka) of about 105 L·mol-1. The enthalpy contribution to the free energy of binding was little, and nearly three times less than the entropic term TΔS calculated from measured values of Ka and ΔH. Thus, the binding of CT-DNA to Mel is primarily driven by entropy, demonstrating electrostatic and hydrophobic interactions playing roles in the formation of the complex. The ionic strength effect and single-stranded DNA (ssDNA) quenching effect further verified that electrostatic interaction and hydrophobic interactions coexist between them and electrostatic interaction is the predominant one. | |
| Keywords: melittin CT-DNA conformation complex | |
| 投稿时间：2021-11-01 修订日期：2021-12-20 | |
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| 张文龙,胡颖媛,王颖莉,李睿,李建丽,杨斌盛.蜂毒肽与CT-DNA的相互作用[J].无机化学学报,2022,38(4):629-636. | |
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