SUNY at Albany
June 19-23, 2001
Classification of CD and absorption spectra in the Soret band of H2TMPyP bound to various synthetic polynucleotides
Meso-tetrakis(N-methyl pyridinium-4-yl)porphyrin(H2TMPyP) has been known to bind to the minor groove of poly[d(A-T)2] and intercalate to poly[d(G-C)2] (Biophys. Chem. (1998), 70, 1-10). In this work, those bindings were classified by circular dichroism(CD) and absorption spectroscopy. H2TMPyP in the minor groove of poly[d(A-T)2] at a low binding ratio showed hypochromism and a red shift in the absorption band and a positive CD peak while hypochromism and a red shift in the absorption band and a negative CD in the Soret absorption region were observed when it is intercalated poly[d(G-C)2] at a low binding ratio. At a high binding ratio for both A-T and G-C rich DNA, an excitonic CD was observed, suggesting the stacking of H2TMPyP along DNA. When H2TMPyP binds to non-alternating polynucleotides, a positive band at short wavelengths and a negative at long wavelengths were apparent in CD spectrum. The sign of CD of H2TMPyP complexed with alternating polynucleotide were opposite from that of non-alternating homopolymers, indicating that the nature of base does not affect to the sign of CD but the arrangement of DNA bases determines the sign of excitonic CD spectrum.
Sun-Hee Jeon(1), Soo-min Lee(1), Bok-Jo Kim(2), Sung-Wook Han(2) and Seog K. Kim(1*)
Department of Chemistry(1), Yeungnam University, Republic of Korea
*Department of Environmental Engineering)(2), Kyungwoon University, Republic of Korea