ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The kinetics of ethidium's intercalative binding to DNA packaged in bacteriophage T7 and two T7 deletion mutants have been determined, using enhancement of fluorescence to quantitate binding. At a constant ethidium concentration, the results can be described as first-order binding with two different rate constants, k1* (= k1 + k-1) and k2* (= k2 + k-2). The larger rate constant (k1*) was at least four orders of magnitude smaller than the comparable first-order forward rate constant for binding to DNA released from its capsid. At 25°C values of k1* decreased as the amount of DNA packaged per internal volume increased. This latter observation indicates that the rate of ethidium's binding to packaged T7 DNA is limited by an event that occurs inside of the DNA-containing region of T7, not by the crossing of T7 capsid's outer shell. Arrhenius plots of kM1* are biphasic, indicating a transition for packaged DNA at a temperature of 20°C. The data indicate that k1* s are limited by either sieving of ethidium during its passage through the packaged DNA or subsequent hindered intercalation.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360250713
Permalink