The influence of single-strand breaks on the kinetics of denaturation of DNA

✍ Scribed by A. J. Hoff; Joh. Blok

• Publisher: Wiley (John Wiley & Sons)
• Year: 1970
• Tongue: English
• Weight: 652 KB
• Volume: 9
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1970.360091105

✦ Synopsis

Abstract

The influence of single‐strand breaks on the kinetics of the relaxation of DNA in a solution of low ionic strength has been investigated by a temperature jump method. The relaxation of DNA after a jump of 0.7 °C in the melting region has been monitored by measuring the extinction at 260 nm. For essentially monodisperse T4 DNA (M = 130 × 10^6^) two distinct relaxation times have been observed, that depend markedly on the initial extent of denaturation 1 − θ. The larger relaxation time decreases from 450 sec to about 300 sec, the smaller one from 55 see to 30 when 1 − θ increases from 0.03 to about 0.8. The dependence of these relaxation times on the average number of single‐strand breaks per molecule (p) appears to be very small up to p = 100. However, the relative contribution of the slow process decreases sharply when p increases from 0.6 to 30 and remains nearly constant for larger p. The observations are discussed in the light recent theories of the kinetics of denaturation.