Sim Adelene Y L, Lipfert Jan, Herschlag Daniel, Doniach Sebastian
Applied Physics Department, Stanford University, Stanford, California 94305, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Aug;86(2 Pt 1):021901. doi: 10.1103/PhysRevE.86.021901. Epub 2012 Aug 1.
Short single-stranded nucleic acids are ubiquitous in biological processes; understanding their physical properties provides insights to nucleic acid folding and dynamics. We used small-angle x-ray scattering to study 8-100 residue homopolymeric single-stranded DNAs in solution, without external forces or labeling probes. Poly-T's structural ensemble changes with increasing ionic strength in a manner consistent with a polyelectrolyte persistence length theory that accounts for molecular flexibility. For any number of residues, poly-A is consistently more elongated than poly-T, likely due to the tendency of A residues to form stronger base-stacking interactions than T residues.
短单链核酸在生物过程中无处不在；了解它们的物理性质有助于深入了解核酸折叠和动力学。我们使用小角X射线散射来研究溶液中8 - 100个残基的同聚单链DNA，无需外力或标记探针。随着离子强度的增加，聚胸腺嘧啶（Poly - T）的结构系综发生变化，其方式与考虑分子柔韧性的聚电解质持久长度理论一致。对于任何数量的残基，聚腺嘌呤（Poly - A）始终比聚胸腺嘧啶更细长，这可能是由于腺嘌呤残基比胸腺嘧啶残基形成更强碱基堆积相互作用的倾向。
