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Flow dichroism of T7 DNA as a function of salt concentration
Author(s) -
Rizzo Vincenzo,
Schellman John
Publication year - 1981
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.1981.360201009
Subject(s) - chemistry , persistence length , circular dichroism , salt (chemistry) , electrostatics , dna , range (aeronautics) , function (biology) , chemical physics , dichroism , persistence (discontinuity) , interpretation (philosophy) , crystallography , optics , molecule , physics , organic chemistry , biochemistry , materials science , geotechnical engineering , programming language , computer science , engineering , evolutionary biology , composite material , biology
Measurements have been made on the flow dichroism of T7 DNA as a function of NaCl concentration. In high salt, our results are compatible with an optical factor of −1.4 and a persistence length of 470 Å. The former is in agreement with expectations from the x‐ray diffraction structure of fibrous B–DNA, and the latter is in the midrange of recent determinations. As salt concentration is decreased, the persistence length increases. The relation of our study to other recent investigations and with current theories of the electrostatic contribution to persistence length is discussed. We note that the separation of the electrostatic expansion factor into long‐ and short‐range effects is somewhat arbitrary and might affect the interpretation of different experimental results in different ways. Finally, our hydrodynamic factors are consistent with a chain which is partially free‐draining. This goes against the traditional interpretation but is in agreement with two recent observations.