Tetraarylporphyrin as a Selective Molecular Cap for Non‐Watson–Crick Guanine–Adenine Base‐Pair Sequences

Abstract

Well protected: Porphyrins act as a molecular cap (see picture) to selectively stabilize a non‐self‐complementary non‐Watson–Crick DNA structure through additional hydrophobic interactions. At the same time, these porphyrins serve as an efficient internal sensor of the newly formed secondary structure.

Vibrational and electronic circular dichroism study of the interactions of cationic porphyrins with (dG‐dC)10and (dA‐dT)10

“…Sequential oligonucleotides (dG-dC) 10 and (dA-dT) 10 were purchased from Generi Biotech, Czech Republic; 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin-Cu(II) tetrachloride (Cu(II)TMPyP) was prepared from 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetratosylate salt (Porphyrin Systems, Germany) according to published procedures. 27 The UV-VIS and ECD spectra were collected with a Jasco J-810 spectropolarimeter in the UV (230-300 nm) and Soret (375-470 nm) spectral regions using 1-cm path-length quartz cuvette.…”

“…Cu(II)TMPyP alone provided nonspecific noisy ECD spectrum. The substantial hypochromicity (*20 and 50%) and a weak red shift (*5 nm), wellknown spectral characteristics typical of the intercalative binding mode, 24 were observed in the Soret spectral region for the (dG-dC) 10 -Cu(II)TMPyP complexes. The hypochromic effect increased with decreasing ratio.…”

“…TMAP interacted with the major groove of (dG-dC) 10 , was semiintercalated into (dA-dT) 10 , and caused significant variation in the structure of both oligonucleotides at the higher concentration of porphyrin. The spectroscopic techniques used in this study revealed that porphyrin binding with AT sequences caused substantial variation of the DNA structure.…”

“…and it was shown that the interaction of Cu(II)TMPyP with (dA-dT) 10 via external binding to the phosphate backbone and major groove binding caused transition from the B to the non-B conformer. TMAP interacted with the major groove of (dG-dC) 10 , was semiintercalated into (dA-dT) 10 , and caused significant variation in the structure of both oligonucleotides at the higher concentration of porphyrin.…”

“…The tetrachloride (TMAP), with (dG-dC) 10 and (dA-dT) 10 were studied by combination of vibrational circular dichroism (VCD) and electronic circular dichroism 10 , which has been well described, was characterized by a new VCD ''marker''…”