title: DNA-binding geometry dependent energy transfer from 4',6-diamidino-2-phenylindole to cationic porphyrins.
abstract: The circular and linear dichroism (CD and LD) spectral properties of the meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP)-DNA complex at a [porphyrin]/[DNA] ratio below 0.015 showed that TMPyP intercalates between DNA base pairs. Contrarily, when cis-bis(N-methylpyridinium-4-yl)porphyrin (BMPyP) is associated with DNA, no CD spectrum was induced and a bisignate LD spectrum was observed. These spectral properties of both the TMPyP and BMPyP were essentially retained when the minor groove of the DNA was saturated with 4',6-diamidino-2-phenylindole (DAPI). The fluorescence of the DNA-bound DAPI was effectively quenched by BMPyP and TMPyP. The quenching by BMPyP can be described through a pure static mechanism while TMPyP quenching produced an upward bending curve in the Stern-Volmer plot. Quenching efficiency was by far greater than predicted by the "sphere of action model", suggesting that the DNA provides some additional processes for an effective energy transfer.
authors: Department of Chemistry, Yeungnam University, Gyeongsan City, Gyeongbuk, 712-749, Republic of Korea.
authors: Biao
authors: B
authors: Jin
authors: Kil Sik
authors: KS
authors: Min
authors: Sung Wook
authors: SW
authors: Han
authors: Seog K
authors: SK
authors: Kim
mesh_terms: D002412:Cations / Q000737:chemistry*; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D004735:Energy Transfer; D007211:Indoles / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*
chemical_list: D002412:Cations; D007211:Indoles; D011166:Porphyrins; C540459:meso-tetrakis(N-methylpyridinium-4-yl)porphyrin; C007293:DAPI; D004247:DNA