金属螯合亲和色谱中的疏水作用

通过考察盐溶盐和盐析盐浓度对蛋白质在IDA裸柱和金属螯合柱上保留行为的影响,详细研究了金属螯合色谱中的疏水作用,疏水作用的发生、形成的条件以及不同条件下对蛋白质保留值的贡献。实验结果表明,在高浓度和低浓度的盐溶盐以及低浓度盐析盐中,蛋白质在金属螯合柱上的保留主要受静电和配位作用控制,而疏水作用对蛋白质的保留影响很小。对弱亲和性的金属螯合柱以静电作用为主,其大小可用参数Q表征;对强亲和性的IDA-Cu（Ⅱ）柱以配位作用为主。仅在高浓度的盐析盐中,金属螯合柱才呈现较强的疏水作用,支配蛋白质保留。实验证明,金属螯合色谱中疏水作用主要来自固定相间隔臂中的疏水碳链和盐析盐对蛋白质的增疏作用,利用这种疏水作用有可能改善金属螯合色谱分离的选择性。     

金属螯合亲和色谱中固定金属与蛋白质的作用

在不同PHNaCl的磷酸缓冲体系，比较了牛血清蛋白（BSA）、核糖核酸酶（RNase)、细色素C（Cyt-C)和溶菌酶（Lys)在IDA裸柱和一些金属螯合柱上的保留特性，考察了固定金属对蛋白质保留行为的影响，指出蛋白质在强结合IDA－Cu柱上的保留主要受固定金属和蛋白质间配位作用支配，在弱亲和的IDA－Ni,IDA-Co和IDA－Zn柱上的保留主要受静电作用控制，配位作用为辅，讨论了金属螯合亲和色谱中影响蛋白质和金属配位的主要因素，金属离子的电荷和半径，配位原子对中心离子外层d轨道的影响，以及蛋白质表面配位的组氨酸数目，离解常数和取向，影响金属螯合配体和蛋白质静电作用的主要因素为溶液的PH和蛋白质的等电点pI.     

疏水相互作用色谱中蛋白质保留值的预测

]全面考虑了疏水色谱中蛋白质、固定相和流动相之间涞的各种相互作用,特别强调了流动相中盐和水的作用。提出了一个能够准确预测较宽浓度范围内蛋白质在疏水色谱中保留值的方程式,以实验数据对此方程进行了验证。结果表明,无论洗脱曲线是否存在极小值,本文所提出的方程式都能予以良好地描述。     

疏水作用色谱中流动相组成对溶质保留行为的影响

 首次研究了疏水作用色谱 (HIC)中芳香醇同系物在不同种类盐流动相中的保留行为。以计量置换保留模型中的参数Z分析了HIC中小分子与生物大分子保留行为的差别 ,以及不同流动相组成对两种类型溶质的洗脱范围及洗脱能力的影响。与反相色谱相似 ,芳香醇在HIC中的保留仍存在同系物规律。比较了小分子和生物大分子在不同盐溶液中的Z值变化 ,表明流动相中的盐仅改变小分子与固定相的水合程度 ,而对生物大分子 ,除改变其和固定相水合程度外 ,还会影响生物大分子与固定相接触区的分子构象     

一种金属螯合连续棒色谱柱的制备及色谱性能

金属螯合色谱（IMAC）在生物大分子的分离和纯化中有广泛的应用,通过改变IMAC的洗脱条件和被螯合的金属离子种类,生物大分子可获得选择性分离。目前,IMAC通常以有机和无机微球作固定相,由于柱死体积的存在,使色谱柱空间利用率低,且降低了蛋白质分离的柱效。近年报道的连续棒色谱柱是由直径1μm左右的微粒堆积而成的整体,消除了色谱柱的死体积,该类色谱柱用于蛋白的反相、疏水、离子交换和亲和色谱分离均可获得高的分离效率。然而,至今尚未见到对金属螯合连续棒色谱柱制备及应用的研究报道。对蛋白的IMAC分离机理研究中,研究流动相pH对分离的影响是主要手段之一,但通常研究的pH值的5.0-9.0的窄范围内。本文提出和制备了以交联聚甲基丙烯酸缩水甘油酯连续棒为基质的金属螯合色谱柱,并研究了pH在2.0-11.0的较宽范围内对蛋白保留的影响。     

用参数Z表征疏水色谱中脲浓度与蛋白质分子的构象变化

研究了５种标准蛋白在流动相中含有不同脲浓度条件下的疏水色谱保留行为。当脲浓度不变时，蛋白质的保留仍然服从计量置换保留模型，并可测定在该特定脲浓度条件下蛋白质的Ｚ值。计量置换参数Ｚ可作为疏水色谱中生物大分子的构象变化的表征。     

甲酸－异丙醇体系分离蛋白质时甲酸的作用研究

 本文在反相高效液相色谱上，用甲酸－异丙醇体系作流动相，研究了甲酸浓度变化对蛋白质分离的影响。结果表明当甲酸浓度增加时，蛋白质的保留时间减小和计量置换模型之值的降低反映了甲酸在这个体系中具有洗脱剂的作用。甲酸使蛋白质在流动相中的溶解度增大，具有离子对试剂的作用。在这个体系中甲酸还具有破坏蛋白质结构的功能。     

使用疏水作用色谱研究蛋白质的构象变化

研究了高效疏水作用液相色谱中(HIC)色谱条件改变对蛋白质构象的影响。发现固定相配体的疏水性、温度及流动相中盐的阴离子、阳离子和pH值都影响蛋白质的构象。     

盐酸胍对疏水色谱中蛋白质保留行为的影响

研究了变性剂酸胍对几种蛋白质在高效疏水色谱中保留行为的影响，用液相色谱中溶质的计量置换保留模型和测流动相表面张力及蛋白质紫外吸收光谱方法研究的结果表明：在低浓度范围内，盐酸胍主要以疏水作用影响蛋白质的保留；而在高浓度区域内，盐酸胍的存在则显著影响蛋白质分子的构象，使其保留行为发生变化。     

甲酸－异丙醇体系分离蛋白质时甲酸的作用研究

本文在反相高效液相色谱上，用甲酸－异丙醇体系作流动相，研究了甲酸浓度变化对蛋白质分离的影响。结果表明当甲酸浓度增加时，蛋白质的保留时间减小和计量置换模型之值的降低反映了甲酸在这个体系中具有洗脱剂的作用。甲酸使蛋白质在流动相中的溶解度增大，具有离子对试剂的作用。在这个体系中甲酸还具有破坏蛋白质结构的功能。     

Retention Behavior of Proteins on Glutamic Acid-Boned Silica Stationary Phase

A glutamic acid-bonded silica (Glu-silica) stationary phase with cation-exchange properties was synthesized using l-glutamic acid as ligand and silica gel as matrix. The effects of solution pH value, salt concentration and metal ion on the retention of proteins were examined. The standard protein mixture was separated with a prepared chromatographic column and an iminodiacetic acid column, and compared. The influence of the binding capacity of an immobilized metal ion on the complexation of metal chelate column was studied. The results indicate that the obtained column displays cation-exchange characteristic and better separation ability for proteins. As fixing metal ion on the Glu-silica column, retention of proteins on the column is a cooperative interaction of metal chelate and cation-exchange. The stationary phase shows the typical metal chelate properties with the increase of the sorption capacity of immobilized metal ion.     

Effects of Immobilized Metal Ion on Retention Behaviors of Proteins in Metal Chelate Affinity Chromatography

The chromatographic behaviors of proteins on iminodiacetic acid (IDA) column with and without immobilized metal ion were examined in detail. Comparing the effects of pI, solution pH, and salt concentration on retention of proteins in cation‐exchange chromatography (CEC) and metal chelate affinity chromatography (MCAC), the retention mechanism of proteins was investigated in MCAC. By aid of observing the retention characteristics of proteins on naked IDA and metal chelate columns in high concentration salt‐out salt solution, the hydrophobic interaction in MCAC and the influence of metal ion on it were proved. In terms of the comparison of the thermodynamics of proteins in CEC and MCAC, the thermostability, the conformational change entropy Δ(ΔS⁰) and enthalpy Δ(ΔH⁰), compensation temperature β, the driving force and caloritic effect of proteins in MCAC were discussed. The identity of retention mechanism at protein thermal denaturation in CEC and MCAC was demonstrated by using the compensation relationship between ΔH⁰ and ΔS⁰.     

Chromatographic behaviors of proteins on cation-exchange column

A weak cation-exchanger (XIDACE-WCX) has been synthesized by the indirect method. The chromatographic characteristics of the synthesized packing was studied in detail. The standard protein mixture and lysozyme from egg white were separated with the prepared chromatographic column. The chromatographic thermodynamics of proteins was studied in a wide temperature range. Thermodynamic parameters standard enthalpy change (deltaH0) and standard entropy change (deltaS0) and compensation temperature (beta) at protein denaturation were determined in the chromatographic system. By using obtained deltaS0, the conformational change of proteins was judged in the chromatographic process.The linear relationship between deltaH0 and deltaS0 can be used to identify the identity of the protein retention mechanism in the weak cation-exchange chromatography. The interaction between weak cation-exchanger and metal ions was investigated. Several metal chelate columns were prepared. The effects of introducing metal ion into the naked column on protein retention and the retention mechanism of proteins in the metal chalet affinity chromatography were discussed.     

固定金属离子亲和色谱--蛋白质分离的方法、原理、特性和应用

介绍了固定金属离子亲和色谱法(IMAC)的方法原理、金属螯合柱的制备、固定金属离子与蛋白质的相互作用以及影响这些作用的因素、不同色谱条件下各种作用力对蛋白质保留值的贡献、蛋白质的洗脱原理和IMAC在蛋白质分离纯化中的应用,论述了IMAC的特点、不足、克服的方法和今后应解决的问题。     

Theory and applications of a novel ion exchange chromatographic technology using controlled pH gradients for separating proteins on anionic and cationic stationary phases

pISep is a major new advance in low ionic strength ion exchange chromatography. It enables the formation of externally controlled pH gradients over the very broad pH range from 2 to 12. The gradients can be generated on either cationic or anionic exchangers over arbitrary pH ranges wherein the stationary phases remain totally charged. Associated pISep software makes possible the calculation of either linear, nonlinear or combined, multi-step, multi-slope pH gradients. These highly reproducible pH gradients, while separating proteins and glycoproteins in the order of their electrophoretic pIs, provide superior chromatographic resolution compared to salt. This paper also presents a statistical mechanical model for protein binding to ion exchange stationary phases enhancing the electrostatic interaction theory for the general dependence of retention factor k, on both salt and pH simultaneously. It is shown that the retention factors computed from short time isocratic salt elution data of a model protein can be used to accurately predict its salt elution concentration in varying slope salt elution gradients formed at varying isocratic pH as well as the pH at which it will be eluted from an anionic exchange column by a pISep pH gradient in the absence of salt.     

疏水作用色谱介质的合成及色谱特性研究

利用国产大孔硅胶作基质合成了疏水填料。按照高效疏水作用色谱法,采用梯度洗脱方式分离了6种标准蛋白及唾液中α-淀粉酶和基因工程生产的γ-干扰素。柱子不可逆吸附小、被试验的α-淀粉酶和溶菌酶活性几乎定量被回收。应用合成的色谱填料研究了洗脱剂中盐浓度和温度对蛋白质保留行为的影响,论证了合成填料的色谱属性。     

Effects of electrostatic and hydrophobic interactions on the chromatographic behavior of biopolymers in HPLC columns

The effect of electrostatic and hydrophobic interactions on the chromatographic behavior of biopolymers with the use of chemically bonded silica-based HPLC columns and aqueous buffered mobile phases containing neutral salts in a wide range of concentration is discussed. Two columns packed with stationary phases appositely designed for biopolymer HPLC in size exclusion and anion exchange mode, respectively, are examined. Experimental data are evaluated by plotting the measured isocratic elution volumes of several standard proteins of different isoelectric point against the salt concentration in the mobile phase. Depending on the concentration and nature of salt, both columns exhibit different domains where either sieving effect or electrostatic or hydrophobic interactions are predominant. At sufficiently low salt concentrations electrostatic interactions are predominant leading to either increasing or decreasing elution volumes depending on the sign of the charges on the stationary phase and the protein, respectively. On the other hand, at high salt concentrations of a salt with sufficiently high molal surface tension increment proteins may be retained by hydrophobic interactions.     

Mixed retention mechanism of proteins in weak anion-exchange chromatography

Using four commercial weak anion-exchange chromatography (WAX) columns and 11 kinds of different proteins, we experimentally examined the involvement of hydrophobic interaction chromatography (HIC) mechanism in protein retention on the WAX columns. The HIC mechanism was found to operate in all four WAX columns, and each of these columns had a better resolution in the HIC mode than in the corresponding WAX mode. Detailed analysis of the molecular interactions in a chromatographic system indicated that it is impossible to completely eliminate hydrophobic interactions from a WAX column. Based on these results, it may be possible to employ a single WAX column for protein separation by exploiting mixed modes (WAX and HIC) of retention. The stoichiometric displacement theory and two linear plots were used to show that mechanism of the mixed modes of retention in the system was a combination of two kinds of interactions, i.e., nonselective interactions in the HIC mode and selective interactions in the IEC mode. The obtained U-shaped elution curve of proteins could be distinguished into four different ranges of salt concentration, which also represent four retention regions.