ISSN:
0173-0835
Keywords:
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
The electrophoresis of long polyelectrolytes is considered theoretically, with special attention to duplex DNA. We first discuss quantitative approaches to determine unambiguously the entanglement properties of polymer solutions. Following an idea proposed by Grossman and Soane, we then assume that the “mesh” size of the solution plays the role of a dynamic “pore size” in order to apply theories for gel electrophoresis. In the framework of the Ogston model, we predict that duplex DNA up to 1 kb or more should be separable in dilute (i.e. nonentangled) solutions of high molecular weight polymers. In an entangled solution, and for DNA larger than the pore size, we use a recently developed fluctuation-reptation model to predict the range of sizes in which separation should be possible as a function of electric field E and pore size ξ b. For ξb larger than the Kuhn length of DNA, we predict a separation up to a size N*scaling as E-1ξb-1. For ξb smaller than the Kuhn length, two different regimes are expected. For small electric fields (typically of the order of 10 V/cm), N*should be proportional to E-1ξb-3/3, whereas for high electric fields such as encountered in capillary electrophoresis, we expect that N*is proportional to E-2/5ξb12. These predictions are qualitatively different from earlier ones. Finally, we demonstrate that the finite lifetime of the “pores” in anentangled solution (as opposed to a gel) may lead to a new migration mechanism by constraint release, which is not size-dependent. In contrast with earlier suggestions, we show that, in general, the concentration should be raised above a minimal value significantly higher than the entanglement threshold c*in order to separate large DNA molecules. We propose expressions for this minimal concentration as a function of DNA and polymer sizes. This model suggests that, for a given high molecular weight polymer, the size of the largest DNA that can be separated increases roughly linearly with the viscosity of the solution.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/elps.1150140155
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