Chain flexibility and hydrodynamics of the B and Z forms of pory(dG-dC).pory(dG-dC)

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Abstract
The solution properties of the B and Z forms of poly (dG-dC) .poly (dG-dC) have been measured by static and dynamic laser light scattering. The radius of gyration, persistence length, translational and segnental diffusion coefficients, and the Rouse-Zimm parameters have been evaluated. The persistence length of the Z form determined at 3 M NaCl is about 200 nn compared to 84 and 61 nm respectively for the B forms of poly(d3–dC) .poly-(dS–dC), and calf thymus DNA, both determined at 0.1 M NaCl. The data on persistence length, diffusion coefficients and the Rouse-Ziram parameters indicate a large increase in the chain stiffness of Z DNA compared to the B form. These results are opposite to the ionic strength effects on random sequence native DNAs, for which the flexibility increases with ionic strength and levels off at about 1 M NaCl.