Liquid crystal formation in DNA fragment solutions

Autor: W. Jesse, J. A. P. P. van Dijk, K. Kassapidou, J. R. C. van der Maarel
Rok vydání: 1998
Předmět:
Zdroj: Biopolymers. 46:31-37
ISSN: 1097-0282
0006-3525
DOI: 10.1002/(sici)1097-0282(199807)46:1<31::aid-bip3>3.0.co;2-z
Popis: The critical volume fractions pertaining to the formation of DNA liquid crystals were obtained from polarization microscopy, 31P-nmr, and phase separation experiments. The DNA length (approximately one to two times the persistence length 50 nm), ionic strength, and counterion variety dependencies are reported. The cholesteric–isotropic transition is interpreted in terms of the coexistence equations, which are derived from the solution free energy including orientational entropy and excluded volume effects. With the wormlike chain as reference system, the electrostatic contribution to the free energy is evaluated as a thermodynamic perturbation in the second virial approximation with a Debye–Huckel potential of mean force. The hard core contribution has been evaluated with scaled particle theory and/or a simple generalization of the Carnahan–Starling equation of state for hard spheres. For sufficiently high ionic strengths, the agreement is almost quantitative. At lower amounts of added salt deviations are observed, which are tentatively attributed to counterion screening effects. The contour length dependence agrees with a DNA persistence length 50 nm. © 1998 John Wiley & Sons, Inc. Biopoly 46: 31–37, 1998
Databáze: OpenAIRE
Externí odkaz: