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Role of structure-proteins in the porphyrin–DNA interaction

Paper ID Volume ID Publish Year Pages File Format Full-Text
30254 44466 2009 9 PDF Available
Title
Role of structure-proteins in the porphyrin–DNA interaction
Abstract

We studied the complexation of meso-tetrakis(4-N-methylpyridyl)porphyrin (TMPyP) with HeLa nucleosomes and compared it to our earlier results on T7 phage nucleoprotein complex (NP) and isolated DNA. To identify binding modes and relative concentrations of the bound TMPyP forms, the porphyrin absorption spectra were analyzed at various base pair/porphyrin ratios. Spectral decomposition and circular dichroism measurements proved that the two main binding modes of TMPyP, i.e., external binding and intercalation occur also in the nucleosomes. The DNA superstructure maintained by the proteins decreases its accessibility for TMPyP similarly in both nucleoproteins. A difference is observed between the partitioning of the two binding modes: in the case of nucleosome the ratio of intercalation to groove-binding is changed from 60/40 to 40/60 as determined for T7 NP and for isolated DNA-s. Using UV and CD melting studies, we revealed that TMPyP destabilizes the DNA–protein interaction in the nucleosomes but not in the T7 phage. Lastly, photoinduced reaction of bound TMPyP caused alterations in DNA structures and DNA–protein interactions within both nucleoprotein complexes; the nucleosomes were found to be more sensitive to the photoreaction.

Keywords
Cationic porphyrin; DNA; Nucleosome; Nucleoprotein complex; Binding; Photoreaction
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Role of structure-proteins in the porphyrin–DNA interaction
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 96, Issue 3, 4 September 2009, Pages 207–215
Authors
, , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us