Electric birefringence of native DNA in an alternating field

✍ Scribed by Stephen J. Miller; James G. Wetmur

• Publisher: Wiley (John Wiley & Sons)
• Year: 1974
• Tongue: English
• Weight: 642 KB
• Volume: 13
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1974.360130107

✦ Synopsis

Abstract

The relaxation of the birefringence of native DNA in solution was investigated in a pulsed sine‐wave electric field. Relaxation times were calculated from the degree of damping of the birefringence signal and were studied as a function of the strength and frequency of the applied field, the molecular weight of the DNA, and the viscosity and ionic strength of the solvent. Relaxation times decrease with increasing field strength. For high‐molecular weight DNA (>10^6^ daltons), the relaxation times decreased with frequency and increased less than linearly with viscosity. For low‐molecular‐weight DNA (<6 × 10^5^ daltons), the relaxation times were independent of frequency, increased linearly with viscosity, and varied with the 1.65 ± 0.1 power of the molecular weight. The average birefringence of high‐molecular‐weight DNA decreased with frequency in 0.001__M__ Na~2~ EDTA plus NaOH, pH 7.0, but is much less frequency‐dependent if the EDTA concentration is reduced tenfold, while the average birefringence of sonicated DNA increases in both solvents with increasing frequency.