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Three persistence lengths for a stiff polymer with an application to DNA B‐Z junctions
Author(s) -
Manning Gerald S.
Publication year - 1988
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360271002
Subject(s) - persistence length , length scale , persistence (discontinuity) , flanking maneuver , twist , bending , dna , chemistry , base pair , physics , polymer , geometry , mechanics , structural engineering , mathematics , nuclear magnetic resonance , thermodynamics , geology , biochemistry , geotechnical engineering , engineering
We discuss three persistence lengths for any locally stiff polymer: the familiar persistence length for bending fluctuations, a persistence length for twisting fluctuations [introduced first by J. Wilcoxon and J. M. Schurr (1983) Biopolymers 22 , 2273–2321], and a persistence length for contraction/extension fluctuations. They correspond to the three classical modes of elastically resilient responses to forces and torques on a thin elastic rod—bending, twisting, and contraction/extension. Although numerically distinct (the persistence length for twist is especially large), the order of magnitude of all three is 100 base pairs (bp) for DNA. With some confidence, therefore, we conclude that DNA exhibits elastic resilience on a scale of 100 bp. Perturbations at both ends of a 100‐bp segment are thus expected to propagate as structural effects throughout the length of the segment, as has been observed experimentally when a 99‐bp segment of B‐DNA is flanked at both ends by sequences with B‐Z transition capability [R. M. Wartell, J. Klysik, W. Hillen, and R. D. Wells (1982) Proc. Natl. Acad. Sci. USA 79 , 2549–2553]. We predict that the observed effect will disappear if Z‐susceptible flanking occurs at only one end of the elastically resilient segment. We suggest, moreover, that similar experiments can determine the maximum length of a DNA segment capable of elastic response.