The persistence length of double-stranded DNA is approximately 150 base pairs (bp), which indicates the stiffness of the DNA polymer. Despite this, DNA segments of 100 bp or less can bend or circularize due to thermal fluctuations and binding energies, such as those involved when DNA wraps around histones. The origin of replication (ORI) is mentioned as a relevant factor, although its direct impact on bending is not clearly established. Understanding the definition of persistence length is crucial, as it describes the distance over which the direction of a polymer segment remains consistent due to its limited flexibility.
PREREQUISITESBiochemists, molecular biologists, and researchers studying DNA mechanics and structure will benefit from this discussion.
Or: the length of the DNA along which a thermally excited bend of 1 radian typically occurs (the DNA is essentially straight over shorter distances). Since the persistance length is based on just thermal fluxuations, it should be possible to bend it further with binding energies for instance (wrapping DNA around histones).Persistence length (P): A lengthscale for polymer stiffness. The distance over which the direction of a polymer segment persists, in the time or ensemble average, owing to limited flexibility of the polymer. For DNA the persistence length is ~50 nm, i.e., ~150 bp. Chains Ł P in length require a lot of work (free energy) to bend much, yet in nucleosomes roughly one persistence length of DNA is bent in nearly two full turns.