ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Fluorescein mercuric acetate causes the unwinding of DNA and binds to the separated bases. This unwinding process can be followed by measuring absorption changes of this reagent. For untreated calf thymus DNA, the initial rate was very slow, and the shape of the kinetic curve was sigmoidal. When double-strand breaks of DNA were produced by DNase II treatment or sonication, the initial rate increased and the sigmoidal character disappeared. The initial rate was shown to be proportional to the concentration of helix ends. From this relation the rate of unwinding was estimated to be 2.0 base pairs/sec at 1.0 × 10-5M fluorescein mercuric acetate and 25°C. DNase I treatment, which produces single-strand breaks and a smaller number of double-strand breaks, also increased the initial rate. However, this increase was due only to the double-strand breaks, that is, single-strand breaks had no significant effect on the initial rate. Also, uv irradiation increased the initial rate linearly with uv dose, at least up to 2 × 105 erg/mm2, suggesting that this increase is due to photoproducts other than usual pyrimidine dimers. We discuss the usefulness of this kinetic method in structural studies of DNA.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1980.360190505
