Force and Scale Dependence of the Elasticity of Self-Assembled DNA Bottle Brushes
Force and Scale Dependence of the Elasticity of Self-Assembled DNA Bottle Brushes
复制标题
自组装 DNA 瓶刷弹性的力和尺度依赖性
作者：
M. S. Rocha;I. M. Storm;R. F. Bazoni;É. B. Ramos;A. Hernández;M. C. Cohen Stuart;F. Leermakers;R. de Vries
作为一个模型系统来研究瓶刷聚合物的弹性，我们在这里介绍自组装的DNA瓶刷，由一个DNA的主链，可以是很长的，仍然精确定义的长度，和精确的单分散的多肽侧链，物理绑定到DNA的主链。多肽侧链具有二嵌段结构，其中一个嵌段是与DNA强烈结合的小古细菌类核蛋白Sso 7 d。另一个嵌段是净中性、亲水性无规卷曲多肽，长度正好为798个氨基酸。光散射表明，饱和刷的接枝密度是一个侧链每5.6 nm的DNA主链。根据小角X射线散射，刷直径为D = 17 nm。用原子力显微镜（AFM）分析了吸附态DNA瓶刷的结构，发现饱和态DNA瓶刷的有效持久性为Peff = 95 nm，而用光镊测量单个DNA瓶刷的力-延伸曲线，发现Peff = 15 nm。后者等于由单独的Sso 7 d结合阻断剂包被的DNA的预期值。这两个测量之间的明显差异是合理化的瓶刷弹性的规模依赖性，使用以前开发的理论来分析在低离子强度的DNA的规模依赖性静电硬化。
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.
影响因子：
5.5
作者：
Dobrynin AV;Carrillo JM;Rubinstein M
通讯作者：
Rubinstein M
影响因子：
5.6
作者：
Rivetti, C;Guthold, M;Bustamante, C
通讯作者：
Bustamante, C
影响因子：
3
作者：
Ng, L;Grodzinsky, AJ;Ortiz, C
通讯作者：
Ortiz, C