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Force and Scale Dependence of the Elasticity of Self-Assembled DNA Bottle Brushes
Macromolecules ( IF 5.1 ) Pub Date : 2017-12-28 00:00:00 , DOI: 10.1021/acs.macromol.7b01795 Márcio Santos Rocha 1 , Ingeborg M. Storm 2 , Raniella Falchetto Bazoni 1 , Ésio Bessa Ramos 1 , Armando Hernandez-Garcia 3 , Martien A. Cohen Stuart 2 , Frans Leermakers 2 , Renko de Vries 2
Macromolecules ( IF 5.1 ) Pub Date : 2017-12-28 00:00:00 , DOI: 10.1021/acs.macromol.7b01795 Márcio Santos Rocha 1 , Ingeborg M. Storm 2 , Raniella Falchetto Bazoni 1 , Ésio Bessa Ramos 1 , Armando Hernandez-Garcia 3 , Martien A. Cohen Stuart 2 , Frans Leermakers 2 , Renko de Vries 2
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As a model system to study the elasticity of bottle-brush polymers, we here introduce self-assembled DNA bottle brushes, consisting of a DNA main chain that can be very long and still of precisely defined length, and precisely monodisperse polypeptide side chains that are physically bound to the DNA main chains. Polypeptide side chains have a diblock architecture, where one block is a small archaeal nucleoid protein Sso7d that strongly binds to DNA. The other block is a net neutral, hydrophilic random coil polypeptide with a length of exactly 798 amino acids. Light scattering shows that for saturated brushes the grafting density is one side chain per 5.6 nm of DNA main chain. According to small-angle X-ray scattering, the brush diameter is D = 17 nm. By analyzing configurations of adsorbed DNA bottle brushes using AFM, we find that the effective persistence of the saturated DNA bottle brushes is Peff = 95 nm, but from force–extension curves of single DNA bottle brushes measured using optical tweezers we find Peff = 15 nm. The latter is equal to the value expected for DNA coated by the Sso7d binding block alone. The apparent discrepancy between the two measurements is rationalized in terms of the scale dependence of the bottle-brush elasticity using theory previously developed to analyze the scale-dependent electrostatic stiffening of DNA at low ionic strengths.
中文翻译：
自组装DNA奶瓶刷的弹性的力和尺度依赖性
作为研究瓶刷聚合物弹性的模型系统，我们在这里介绍自组装的DNA瓶刷，它由可以非常长且仍具有精确定义的长度的DNA主链以及精确地单分散的多肽侧链组成。与DNA主链物理结合。多肽侧链具有双嵌段结构，其中一个嵌段是与DNA牢固结合的小古细菌核苷蛋白Sso7d。另一个嵌段是具有正好798个氨基酸长度的净中性，亲水性无规卷曲多肽。光散射表明，对于饱和的刷子，嫁接密度是DNA主链每5.6 nm的一条侧链。根据小角度X射线散射，刷子直径为D= 17 nm。通过使用AFM分析吸附的DNA瓶刷的配置，我们发现饱和DNA瓶刷的有效持久性为P eff = 95 nm，但是从使用光镊测量的单个DNA瓶刷的力-延伸曲线，我们发现P eff = 15纳米 后者等于仅由Sso7d结合嵌段包被的DNA的预期值。使用先前开发的用于分析低离子强度下DNA的比例依赖性静电硬化的理论，根据瓶刷弹性的比例依赖性合理化了这两种测量之间的明显差异。
更新日期：2017-12-28
中文翻译：
自组装DNA奶瓶刷的弹性的力和尺度依赖性
作为研究瓶刷聚合物弹性的模型系统，我们在这里介绍自组装的DNA瓶刷，它由可以非常长且仍具有精确定义的长度的DNA主链以及精确地单分散的多肽侧链组成。与DNA主链物理结合。多肽侧链具有双嵌段结构，其中一个嵌段是与DNA牢固结合的小古细菌核苷蛋白Sso7d。另一个嵌段是具有正好798个氨基酸长度的净中性，亲水性无规卷曲多肽。光散射表明，对于饱和的刷子，嫁接密度是DNA主链每5.6 nm的一条侧链。根据小角度X射线散射，刷子直径为D= 17 nm。通过使用AFM分析吸附的DNA瓶刷的配置，我们发现饱和DNA瓶刷的有效持久性为P eff = 95 nm，但是从使用光镊测量的单个DNA瓶刷的力-延伸曲线，我们发现P eff = 15纳米 后者等于仅由Sso7d结合嵌段包被的DNA的预期值。使用先前开发的用于分析低离子强度下DNA的比例依赖性静电硬化的理论，根据瓶刷弹性的比例依赖性合理化了这两种测量之间的明显差异。
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