本文選題：氯離子通道 + ClC-0　； 參考：《武漢大學(xué)》2010年博士論文

【摘要】： ClC氯通道蛋白是一類重要的離子通道蛋白,它們廣泛存在于原核細(xì)胞和真核細(xì)胞中,包括哺乳動物中。它具有重要的生理功能,當(dāng)它的功能缺失時會引起許多疾病,如肌強直,不孕不育,耳聾等。它在細(xì)菌中的同源物的晶體結(jié)構(gòu)在2002年被測得。在此之后一系列實驗研究出現(xiàn),但是實驗只能得到通道的宏觀性質(zhì),對于微觀分子機制卻很少涉及,因此從分子角度研究它的結(jié)構(gòu)與功能的關(guān)系具有非常重要的意義。我們利用分子動力學(xué),連續(xù)靜電計算,建模等方法,研究了ClC氯通道的結(jié)構(gòu)和功能特性,揭示其微觀機制。 1.提出ClC-0氯離子通道導(dǎo)電性質(zhì)的三態(tài)多離子輸運模型 我們提出了一個三態(tài)多離子輸運模型,它能很好地解釋氯離子通道ClC-0的導(dǎo)電特性。將速率理論用于此模型,得到電流-電壓和電導(dǎo)率-濃度的關(guān)系。模型中的五個可調(diào)參數(shù),是通過擬合野生型ClC-0和它的變異體K519C的實驗數(shù)據(jù)得到的。作為檢驗,將這個模型得到的數(shù)據(jù)與采用其他計算和模擬方法得到的數(shù)據(jù)進(jìn)行比較。結(jié)果表明,從這個模型計算出的不同氯離子占據(jù)態(tài)之間的能量差與通過解泊松-玻爾茲曼方程得到的結(jié)合自由能是一致的。從此模型得到的平均導(dǎo)電離子數(shù)和離子通過速率與實驗上的結(jié)果也是一致的。根據(jù)這個模型,由于殘基K519變異成C519產(chǎn)生的電導(dǎo)率的下降能被歸結(jié)為K519C變異對各個態(tài)之間轉(zhuǎn)換速率常數(shù)的影響。這個工作有助于人們理解ClC-0的導(dǎo)電機制。 2.研究ClC-ec1中殘基變異對氯離子靜電結(jié)合自由能的影響 ClC通道蛋白的殘基變異導(dǎo)致蛋白功能的改變,引發(fā)許多疾病�，F(xiàn)已查明,ClC蛋白功能的實現(xiàn)與氯離子在通道中的結(jié)合能密切相關(guān)。因此研究殘基變異對ClC-ec1功能的影響可以通過研究殘基變異對氯離子在通道中的結(jié)合能的影響來體現(xiàn)。我們系統(tǒng)地研究了各種殘基變異對氯離子在通道中的結(jié)合能的影響。通過使用全原子分子動力學(xué)模擬和靜電計算,揭示出殘基變異引起的電荷變化和殘基與氯離子結(jié)合位點的距離是影響氯離子結(jié)合能的重要因素。這一工作在分子層次上使人們認(rèn)識了ClC通道蛋白的殘基變異對蛋白功能影響的實質(zhì)。
[Abstract]:CLC chloride channel proteins are important ion channel proteins which are widely distributed in prokaryotic cells and eukaryotic cells including mammals. It has important physiological functions. When its function is absent, it can cause many diseases, such as myotonia, infertility, deafness and so on. The crystal structure of its homologues in bacteria was measured in 2002. After this, a series of experimental studies appeared, but the experiment can only get the macroscopic properties of the channel, but it is seldom involved in the micro molecular mechanism. Therefore, it is very important to study the relationship between the structure and the function from the molecular point of view. By means of molecular dynamics, continuous electrostatic calculation and modeling, the structure and functional characteristics of chlorine channels of ClC have been studied, and the microscopic mechanism has been revealed. 1. A three-state multi-ion transport model for the conductivity of ClC-0 chloride channel is presented. A three-state multi-ion transport model is proposed, which can explain the conductivity of chloride channel ClC-0 well. Applying the rate theory to this model, the relationship between current-voltage and conductivity-concentration is obtained. The five adjustable parameters in the model are obtained by fitting the experimental data of wild type ClC-0 and its variant K519C. As a test, the data obtained by this model are compared with those obtained by other calculation and simulation methods. The results show that the energy difference between the different chloride ion occupied states calculated from this model is consistent with the binding free energy obtained by solving Poisson Boltzmann equation. The average number of conducting ions and the ion passing rate obtained from the model are in agreement with the experimental results. According to this model, the decrease of conductivity due to the mutation of K519 into C519 can be attributed to the effect of K519C variation on the conversion rate constant between states. This work helps to understand the conductive mechanism of ClC-0. 2. 2. The effect of residue variation on the electrostatic binding free energy of chloride ions in ClC-ec1 was studied. The residue variation of ClC-channel protein led to the change of protein function and caused many diseases. It has been found that the function of ClC protein is closely related to the binding energy of chloride ions in the channel. Therefore, the effect of residue variation on the function of ClC-ec1 can be demonstrated by studying the effect of residue variation on the binding energy of chloride ions in the channel. We have systematically studied the effects of various residue variations on the binding energies of chloride ions in channels. By means of full atomic molecular dynamics simulation and electrostatic calculation, it is revealed that the change of charge caused by residue variation and the distance between residue and chloride binding sites are important factors affecting the binding energy of chlorine ions. At the molecular level, the effect of CLC channel protein residue variation on protein function has been recognized.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2010
【分類號】：R341

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相關(guān)期刊論文 前3條

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本文編號：2079646