Changes in the c.d. spectra of calf thymus DNA induced by sequential polypeptides in trifluoroethanol solutions. Part II.
Interactions between calf thymus DNA and (L-Arg-X-Gly)n sequential polypeptides (where X = L-Ala, Val, Leu, Ile, Nva, Nle) in trifluoroethanol: water (40:60) solutions in the salt range of 0.12-0.5 M NaCl, were studied using c.d. spectroscopy. It was found that DNA tertiary structure (psi form) is modulated by the nature of the polypeptides (variation of X residue). The effect of the secondary structure of polypeptides on the formation of psi-DNA was also analysed. Unordered polypeptides destabilized psi aggregates, while helical polypeptides favoured DNA tertiary structure. A loss of tertiary structure was observed in the presence of the (L-Arg-L-Val-Gly)n, which can be attributed to the ability of valine to suppress psi-type DNA.
Panou-Pomonis
E
E
Department of Chemistry, University of Ioannina, Greece.
Tsikaris
V
V
Sakarellos
C
C
Sakarellos-Daitsiotis
M
M
Marraud
M
M
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D012996:Solutions; D013950:Thymus Gland / Q000378:metabolism; D014270:Trifluoroethanol / Q000737:chemistry*
D010455:Peptides; D012996:Solutions; D014270:Trifluoroethanol; D004247:DNA