Self-diffusion of entangled linear and circular DNA molecules: Dependence on length and concentration
Self-diffusion of entangled linear and circular DNA molecules: Dependence on length and concentration
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DOI：
10.1021/ma070051h
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发表时间：
2007-05-01
期刊：
影响因子：
5.5
通讯作者：
Smith, Douglas E.
中科院分区：
文献类型：
--
作者：
Robertson, Rae M.;Smith, Douglas E.
通过跟踪单个荧光标记示踪分子的布朗运动来测量不同长度和浓度的DNA分子的自扩散系数（D）。检查了四种可能的情况：线性示踪剂分子被线性分子包围（L-L），圆形示踪剂被线性包围（C-L），线性示踪剂被圆形包围（L-C）和圆形包围（C-C）。对于6和11个双链酶对（kbp），DNA D对拓扑结构基本上不敏感，并且与Rouse标度一致地变化（D类似于L-1C-0.5）。与此相反，25和45 kbp的DNA拓扑结构有很强的影响。在lmg/mL下，我们发现DC-C > DL-C > DL-L > DC-L。在L-L、L-C和C-C情况下，在类似于6倍分子重叠浓度下观察到从与Rouse模型一致的缩放到与爬行模型一致的缩放的交叉（D类似于L-2C-1.75）。相比之下，DC-L随着浓度的增加而急剧下降，表明这种情况下的过程比爬行慢得多。
Self-diffusion coefficients (D) of DNA molecules of varying length and concentration were measured by tracking the Brownian motion of individual fluorescently labeled tracer molecules. Four possible cases were examined: linear tracer molecules surrounded by linear molecules (L-L), circular tracers surrounded by linears (C-L), linear tracers surrounded by circles (L-C), and circles surrounded by circles (C-C). With 6 and 11 kilobasepair (kbp) DNA D was largely insensitive to topology and varied consistent with Rouse scaling (D similar to L-1C-0.5). In contrast, with 25 and 45 kbp DNA topology had a strong influence. At 1 mg/mL we found DC-C > DL-C > DL-L > DC-L. In the L-L, L-C, and C-C cases a crossover from scaling consistent with the Rouse model to scaling consistent with the reptation model (D similar to L-2C-1.75) was observed at similar to 6 times the molecular overlap concentration. In contrast, DC-L decreased much more steeply with concentration, indicating that a process much slower than reptation governs that case.