title: Kinetics of disassembly of a DNA-bound porphyrin supramolecular array.
abstract: trans-Bis(N-methylpyridinium-4-yl)diphenylporphine forms extended, organized assemblies on DNA templates under appropriate conditions of concentration, ionic strength, and temperature. Addition of beta-cyclodextrin to these arrays leads to their disassembly as evidenced by changes in extinction, circular dichroism, and resonance light scattering spectra. The structure or flexibility of the polymer template has an effect on the rate of disassembly; the reaction is faster on a poly(dG-dC)(2) surface than on ct DNA. The kinetic profiles for the disassembly process can be fit with great precision with a two-kinetic parameter equation in which the rate constant is itself a function of time. The reaction rate, studied in the presence of excess beta-CD, shows a dependence on the mode of detection. A model is presented to account for these observations in which the arrays become increasingly reactive with time due to beta-CD attack at the interior of the porphyrin assemblies as well as the ends.
authors.affiliation: Department of Chemistry, Swarthmore College, Swarthmore, Pennsylvania 19081, USA. rpaster1@swarthmore.edu
authors.forename: Robert F
authors.initials: RF
authors.lastname: Pasternack
authors.forename: Esther J
authors.initials: EJ
authors.lastname: Gibbs
authors.forename: Derek
authors.initials: D
authors.lastname: Bruzewicz
authors.forename: David
authors.initials: D
authors.lastname: Stewart
authors.forename: Kelly Shannon
authors.initials: KS
authors.lastname: Engstrom
mesh_terms: D002942:Circular Dichroism; D003505:Cyclodextrins / Q000737:chemistry; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D011166:Porphyrins / Q000737:chemistry* / Q000378:metabolism; D013053:Spectrophotometry; D013698:Templates, Genetic; D047392:beta-Cyclodextrins
chemical_list: D003505:Cyclodextrins; D011166:Porphyrins; D047392:beta-Cyclodextrins; D004247:DNA; C031215:betadex