title: Interactions of norharman and harman with DNA.
abstract: The interactions of norharman (9H-pyrido [3,4-b] indole) and harman (1-methyl-9H-pyrido [3,4-b] indole) with DNA were studied. DNA caused remarkable fluorescence quenching and change in the absorption spectra of the dyes. Scatchard plots obtained by optical titration gave Kd values of 2.2 X 10(-5)M and 7.7 X 10(-6)M, and apparent numbers of binding sites of 0.13/base and 0.12/base for norharman and harman, respectively. Agarose gel electrophoresis of circular DNA, closed in the presence or absence of norharman revealed that the dye intercalates DNA, thereby causing 17 +/- 3 degrees unwinding of the double helix.
mesh_terms: D000470:Alkaloids / Q000031:analogs & derivatives; D001665:Binding Sites; D002243:Carbolines; D003090:Coliphages; D004247:DNA; D004270:DNA, Circular; D004278:DNA, Superhelical; D004279:DNA, Viral; D006247:Harmine / Q000031:analogs & derivatives; D009690:Nucleic Acid Conformation; D013050:Spectrometry, Fluorescence; D013057:Spectrum Analysis
chemical_list: D000470:Alkaloids; D002243:Carbolines; D004270:DNA, Circular; D004278:DNA, Superhelical; D004279:DNA, Viral; D006247:Harmine; C005010:harman; D004247:DNA; C010262:norharman