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Comparison of the effects of cationic porphyrins on DNA properties: Influence of GC content of native and synthetic polymers
Author(s) -
Banville Debra L.,
Marzilli Luigi G.,
Strickland James A.,
Wilson W. David
Publication year - 1986
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360251003
Subject(s) - porphyrin , chemistry , intercalation (chemistry) , circular dichroism , dna , cationic polymerization , proton nmr , tetra , intrinsic viscosity , stereochemistry , crystallography , analytical chemistry (journal) , polymer , polymer chemistry , medicinal chemistry , photochemistry , chromatography , organic chemistry , biochemistry
Interactions of meso‐tetra(4‐N‐methylpyridyl)porphyrin [TMpyP(4)], meso‐tetra(2‐N‐methylpyridyl)porphyrin [TMpyP(2)], and meso‐tetra( para ‐N‐trimethylanilinium)porphyrin (TMAP) with several native and synthetic DNAs were studied by a variety of physical techniques: nmr ( 31 P and 1 H), absorption spectroscopy, viscosity, and flow dichroism (FD). Of the three porphyrins studied, only the interaction of TMpyP(4) with poly [d(G‐C) 2 ] was fully consistent with intercalation. In particular, a large increase in viscosity, a downfield 31 P‐nmr signal (ca. ‐1 ppm), and upfield imino proton signals (11 to 12 ppm range) were observed. Comparison of the effects of TMpyP(4) on DNAs of different GC contents revealed larger changes in solution viscosity with increased GC content. However, the characteristic changes in 31 P‐ and 1 H‐nmr spectra were not observed. The viscosity increases observed in studies with poly[d(A‐C)(G‐T)] and C. Perf. DNA were much lower than with poly[d(G‐C) 2 ], M. Lys. DNA, and calf thymus DNA. Thus, GC sequence and content are clearly important. The principal change in the 31 P‐nmr signal of native DNA is the appearance of a very broad shoulder centered at ca. ‐2.0 ppm, which is larger in M. Lys. DNA than in C. Perf. DNA. FD studies indicate highly ordered TMpyP(4) cations arranged perpendicular to the DNA axis of calf thymus DNA. Together, these results suggest the major effects of TMpyP(4) on DNA properties are due to strong GC‐binding interactions that influence DNA structure. The data are consistent with combined intercalative and outside binding interactions of TMpyP(4) with GC regions of DNA. In contrast, similar studies with TMAP suggest that it influences AT regions of DNA by an outside binding mode. On the other hand, TMpyP(2) effects on DNA properties are consistent with nonselective outside binding.