title: DNA interaction with RNase A alters protein conformation.
abstract: DNA-RNase H adducts were used for site specific cleavage of RNA and DNA-RNA duplexes, whereas nonspecific DNA interaction with ribonuclease A (RNase A) has been observed. The aim of this study was to examine the complexation of calf-thymus DNA with RNase A at physiological condition, using constant DNA concentration (12.5 mM) and various protein contents (1 microM to 270 microM). FTIR, UV-visible, and CD spectroscopic methods were used to analyse protein binding mode, the binding constant and the effects of nucleic acid-enzyme interaction on both DNA and protein conformations. Our structural analysis showed a strong RNase-PO2 binding and minor interaction with G-C bases with overall binding constant of K = 6.1 x 10(4) M(-1). The RNase-DNA interaction alters the protein secondary structure with a major reduction of the alpha-helix and increase of the beta-sheet and random structure, while DNA remains in the B-family structure.
authors.affiliation: Department of Chemistry-Biology, University of Québec at Trois-Rivières, Trois-Rivières (Québec), Canada.
authors.forename: C N
authors.initials: CN
authors.lastname: N'Soukpoé-Kossi
authors.forename: C
authors.initials: C
authors.lastname: Ragi
authors.forename: H-A
authors.initials: HA
authors.lastname: Tajmir-Riahi
mesh_terms: D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012259:Ribonuclease, Pancreatic / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D004247:DNA; C427203:calf thymus DNA; D012259:Ribonuclease, Pancreatic