Premium
A 500 MHz proton NMR study of stacking interactions: Binding of tripeptide Lys‐Tyr‐Lys to tetradeoxynucleotide d‐GpCpGpC
Author(s) -
Barthwal R.,
Mujeeb A.,
Kukreti S.,
Gupta A.,
Govil G.
Publication year - 1991
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/jmr.300040202
Subject(s) - chemistry , tripeptide , crystallography , stacking , stereochemistry , two dimensional nuclear magnetic resonance spectroscopy , residue (chemistry) , side chain , chemical shift , proton nmr , ring (chemistry) , helix (gastropod) , peptide , organic chemistry , biochemistry , ecology , snail , biology , polymer
The complete sequential assignment and conformation of d‐GpCpGpC in D 2 O has been determined from ID NMR spectra at 285–320 K and room temperature 2D‐COSY and NOESY spectra. The tetradeoxynucleotide exists primarily as a right handed double helix at 285 K, having T m as 314 K. On binding to a tripeptide Lys‐Tyr‐Lys in a concentration equimolar to tetranucleotide duplex, the Tyr ring protons shift uplifted by 0.14 ppm at 285 K. The increase in T m on binding suggests stabilization of duplex. The existence of intermolecular NOEs between C4 sugar protons and Tyr α C and Lys α C protons give direct evidence of proximity of Tyr residue to the C4 base of d‐GpCpGpC. The conformation of d‐GpCpGpC remains unchanged on binding. The observed results are interpreted in terms of preferential stacking of aromatic ring of Tyr residue with proximal base‐pair of d‐GpCpGpC, stabilized by electostatic interaction of Lysine side chains with backbone phosphates. This is in contrast to intercalculation of aromatic dyes within base‐pairs resulting in a change in sugar conformation at the binding site.