1990 Fiscal Year Final Research Report Summary
Multi-Functional Metal Complexes with DNA Base-Sequence Selectivity
| Project/Area Number |
01470047
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
無機・錯塩・放射化学
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| Research Institution | Tokyo University |
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Principal Investigator |
KURODA Reiko Tokyo Univ., Chemistry, Associate Professor, 教養学部, 助教授 (90186552)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAGISHI Akihiko Tokyo Univ., Chemistry, Associate Professor, 教養学部, 助教授 (70001865)
IWAMOTO Toshitake Tokyo Univ., Chemistry, Professor, 教養学部, 教授 (60011532)
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| Project Period (FY) |
1989 – 1990
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| Keywords | DNA / Intercalator / porphyrin |
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| Research Abstract |
We have studied the molecular basis of DNA-ligand interactions, particularly, sequence recognitions and interplay of multi-functions displayed by various DNA-binding proteins and antibiotics. We have chosen porphyrins as a probe for this study and synthesized various novel porphyrins. Free base porphyrins or their Cu, Ni complexes intercalated between the base pairs of DNA, while Mn complexes with axial ligands bound to DNA by nonintercalative mode. Porphyrins carrying four charged sidechains bound and intercalated similarly into DNA as measured by helix stabilization and DNA unwinding studies in the presence of DNA topoisomerase I. Despite their different bulky sidechains, these complexes gave essentially identical DNase I footprinting patterns. Comparison with single charged porphyrins with less bulky sidechains has shown that the presence of charged sidechains on the porphyrin rather than their identity appears to be critical for efficient DNA intercalation. All the porphyrins which bind to DNA by intercalative mode showed site-specific inhibition of Rsa I digestion of DNA. Out of two recognition sites, a site with GC-rich flanking sequence was selectively inhibited. DNase I footprinting of DNA involving the two sites has shown that 5' immediate to the inhibited cutting-site was protected from DNase I digestion. The protected regions were unexpectedly AT-rich.
We have extended the work to a synthesis of a new series of compounds whose interaction with DNA can be controlled by the second binding part introduced into the compound. At the end of hexamethylene sidechain of a porphyrin, an intercalator which is known to exhibit the same sequence specificity as bleomycin or a photocleaving agent was attached. Their binding with DNA has also been studied with helix stabilization, visible absorption spectroscopy. A crystals of a DNA hexamer-porphyrin complex have been obtained, although they are unfortunately too small for X-ray structural analysis.
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