| Autor: |
Ya-Ping Tsao, Lian-Yong Wang, Shang-Te Hsu, Jain, Moti L., Shan-Ho Chou, Wen-Chang Huang, Jya-Wei Cheng |
| Předmět: |
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| Zdroj: |
Journal of Biomolecular NMR; Nov2001, Vol. 21 Issue 3, p209-220, 12p |
| Abstrakt: |
The solution structure and hydration of a DNA•RNA hybrid chimeric duplex [d(CGC)r(amamam)d(TTTGCG)]2 in which the RNA adenines were substituted by 2′-O-methylated riboadenines was determined using two-dimensional NMR, simulated annealing, and restrained molecular dynamics. Only DNA residue 7T in the 2′-OMe-RNA• DNA junction adopted an O4′-endo sugar conformation, while the other DNA residues including 3C in the DNA 2′-OMe-RNA junction, adopted C1′-exo or C2′-endo conformations. The observed NOE intensity of 2′-O-methyl group to H1′ proton of 4am at the DNA• 2′-OMe-RNA junction is much weaker than those of 5am and 6am. The 2′-O-methyl group of 4am was found to orient towards the minor groove in the trans domain while the 2′-O- methyl groups of 5am and 6am were found to be in the gauche (+) domain. In contrast to the long-lived water molecules found close to the RNA adenine H2 and H1′ protons and the methyl group of 7T in the RNA-DNA junction of [d(CGC)r(aaa)d(TTTGCG)]2, there were no long-lived water molecules found in [d(CGC)r(amamam)d(TTTGCG)]2. This is probably due to the hydrophobic enviroment created by the 2′-O-methylated riboadenines in the minor groove or due to the wider minor groove width in the middle of the structure. In addition, the 2′-O-methylation of riboadenines in pure chimeric duplex increses its melting temperature from 48.5 °C to 51.9 °C. The characteristic structural features and hydration patterns of this chimeric duplex provide a molecular basis for further therapeutic applications of DNA•RNA hybrid and chimeric duplexes with 2′-modified RNA residues. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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