Structural specificity of peptides in Z-DNA formation and energetics of the peptide-induced B-Z transition of poly(dG-m5dC)
| Autor: | Hideo Takeuchi, Issei Harada, Nobuyuki Hanamura |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
chemistry.chemical_classification
Circular dichroism Stereochemistry Circular Dichroism Molecular Sequence Data Peptide DNA Sodium Chloride Methylation Amino acid Z-DNA DNA-Binding Proteins chemistry.chemical_compound Kinetics Polydeoxyribonucleotides chemistry Structural Biology Nucleic Acid Conformation Thermodynamics Nucleotide Amino Acid Sequence Molecular Biology Peptide sequence Oligopeptide binding |
| Zdroj: | Journal of molecular biology. 236(2) |
| ISSN: | 0022-2836 |
| Popis: | The effects of oligopeptide binding in the conformation of double-stranded poly(dG-m5dC) have been examined by circular dichroism spectroscopy. Conversion from the right-handed B-form to the left-handed Z-form occurs very efficiently in the presence of peptides having amino acid sequences of the (Lys-X)n-Lys type, where X is a non-bulky amino acid residue such as Gly, Ala and Lys. The ability to induce the B-Z transition increases rapidly with increasing repeat number n, and the peptides with n = 2-3 readily convert the B-form DNA to the Z-form at a peptide/nucleotide molar ratio of 0.06 to 0.08 (one peptide per 13 to 17 nucleotides). The peptide-induced B-Z transition of poly(dG-m5dC) duplexes takes place even at a physiological salt concentration (150 mM NaCl). The activation energy and van't Hoff enthalpy of the B-Z conversion have been determined to be 124 (+/- 7) and 138 (+/- 12) kJ/mol, respectively, for the (Lys-Gly)2-Lys-induced transition. The van 't Hoff enthalpy of the peptide-induced B-Z transition is particularly small compared to those of the transitions caused by other inducers. The large enthalpic contribution to the Z-DNA formation indicates that the peptide binds preferentially to the Z-arranged DNA phosphate groups and stabilizes the Z-stretch significantly. It is pointed out that some DNA-binding proteins have amino acid sequences that favor Z-DNA. |
| Databáze: | OpenAIRE |
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