Help Privacy Policy Disclaimer
  Advanced SearchBrowse




Journal Article

FTIR and UV spectroscopy of parallel-stranded DNAs with mixed A·T/G·C sequences and their inosine analogs.


Klement,  R.
Emeritus Group Laboratory of Cellular Dynamics, MPI for biophysical chemistry, Max Planck Society;


Jovin,  T. M.
Department of Molecular Biology, MPI for biophysical chemistry, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available

Mohammadi, S., Klement, R., Shchyolkina, A. K., Liquier, J., Jovin, T. M., & Tallandier, E. (1998). FTIR and UV spectroscopy of parallel-stranded DNAs with mixed A·T/G·C sequences and their inosine analogs. Biochemistry, 37, 16529-16537.

Cite as: https://hdl.handle.net/11858/00-001M-0000-0012-FD88-0
The infrared spectra of parallel-stranded (ps) hairpin duplexes with mixed AT/GC composition and either isolated or sequential G·C pairs were studied in comparison with antiparallel-stranded (aps) duplexes and a corresponding set of with molecules with inosine as a G base analog lacking the exocyclic amino group. The ps duplexes showed the characteristic bands for the C2=O2 and C4=O4 stretching vibrations of thymine residues in trans-Watson-Crick A·T pairing at 1683 cm-1 and 1668 cm-1. The latter band was superimposed on the stretching vibration of the free C6=O6 group of guanine. Substitution of guanines by inosines inhibited the formation of ps hairpin duplexes whatever the sequence, demonstrating that in the H-bonding between G and C the 2-NH2 group is necessary for stabilizing all of the investigated ps duplexes with mixed AT/GC composition. This result is in agreement with a model of trans-Watson-Crick G·C base pairs with 2 H-bonds [N2H2(G)-N3(C)) and (N1H(G)-O2(C)]. However, trans-Watson-Crick A·T and G·C base pairs with two H-bonds are not isomorphous, which may explain the decreased stability of the ps, but not the aps, duplexes upon increasing the number of AT/GC junctions. Molecular modelling studies performed on two of the ps duplexes reveal the existence of propeller twist for avoiding a clash between the N2(G) and N4(C) amino groups, and favorable stacking of sequential G·C base pairs. The optimized hairpin ps duplexes invariably incorporated G·C base pairs with two H- bonds, regardless of the initial structures adopted for the force field calculations.