Is DNA a worm-like chain in Couette flow? In search of persistence length, a critical review

摘要

Persistence length is the foremost measure of DNA flexibility. Its origins lie inpolymer theory which was adapted for DNA following the determination of B-DNA structure in 1953. There is no single definition of persistence length used,and the links between published definitions are based on assumptions whichmay, or may not be, clearly stated. DNA flexibility is affected by local ionicstrength, solvent environment, bound ligands and intrinsic sequence-dependentflexibility. This article is a review of persistence length providing a mathema-tical treatment of the relationships between four definitions of persistencelength, including: correlation, Kuhn length, bending, and curvature. Persis-tence length has been measured using various microscopy, force extension andsolution methods such as linear dichroism and transient electric birefringence.For each experimental method a model of DNA is required to interpret the data.The importance of understanding the underlying models, along with theassumptions required by each definition to determine a value of persistencelength, is highlighted for linear dichroism data, where it transpires that nomodel is currently available for long DNA or medium to high shear rateexperiments.