Conformational properties of helical protein polymers with varying densities of chemically reactive groups
Conformational properties of helical protein polymers with varying densities of chemically reactive groups
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DOI：
10.1021/ma051534t
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发表时间：
2006-01-10
期刊：
影响因子：
5.5
通讯作者：
Kiick, KL
中科院分区：
文献类型：
--
作者：
Farmer, RS;Argust, LM;Kiick, KL
蛋白质工程策略已被证明对于生产具有受控性质的各种明确定义的大分子材料是有价值的，这使得它们能够在一系列材料和生物应用中使用。在这项工作中，这种生物合成策略已被用于生产单分散的富含丙氨酸的螺旋蛋白聚合物，其序列为[AAAQEAAAAQAAAQAEAAQAAQ]3和[AAAQAAQAQAAAEAAAQAAQAQ]6。这些蛋白质聚合物的组合物是类似于以前报道的富含丙氨酸的蛋白质聚合物的家族，但化学反应残基的密度和位置已被改变，以促进未来使用这些大分子在阐明生物识别事件中的聚合物结构功能关系。这两种蛋白质聚合物都容易从E.大肠杆菌和纯化的同质性;通过圆二色性光谱（CD）的构象行为的表征表明，他们采用高度螺旋构象的范围内的解决方案的条件下。差示扫描量热法，与CD，表明在这些大分子中从螺旋到线圈的构象转变可以很好地定义，与螺旋度，构象转变，T-m值，和量热的构象随蛋白质聚合物的分子量而变化。红外光谱和CD的组合还揭示了大分子可以在升高的温度和浓度下采用β-折叠结构，并且这种构象转变的存在和动力学似乎与蛋白质聚合物上的带电基团的密度有关。
Protein engineering strategies have proven valuable for the production of a variety of well-defined macromolecular materials with controlled properties that have enabled their use in a range of materials and biological applications. In this work, such biosynthetic strategies have been employed in the production of monodisperse alanine-rich, helical protein polymers with the sequences [AAAQEAAAAQAAAQAEAAQAAQ]3 and [AAAQAAQAQAAAEAAAQAAQAQ]6. The composition of these protein polymers is similar to that of a previously reported family of alanine-rich protein polymers, but the density and placement of chemically reactive residues has been varied to facilitate the future use of these macromolecules in elucidating polymeric structure function relationships in biological recognition events. Both protein polymers are readily expressed from E. coli and purified to homogeneity; characterization of their conformational behavior via circular dichroic spectroscopy (CD) indicates that they adopt highly helical conformations under a range of solution conditions. Differential scanning calorimetry, in concert with CD, demonstrates that the conformational transition from helix to coil in these macromolecules can be well-defined, with helicity, conformational transitions, T-m values, and calorimetric enthalpies that vary with the molecular weight of the protein polymers. A combination of infrared spectroscopy and CD also reveals that the macromolecules can adopt beta-sheet structures at elevated temperatures and concentrations and that the existence and kinetics of this conformational transition appear to be related to the density of charged groups on the protein polymer.