title: Ethidium bromide binding to unstructured and structured 2' GMP.
abstract: For disordered 2' GMP and 5' GMP the ethidium cation (Etd) was found to form 1:1 and 2:1 Eth:nucleotide complex. For alkali metal solution self-structured 2'GMP and 5'GMP Etd was found to form 1:1 and 2:1 Etd: order nucleotide complex. The best computer fit was obtained for a structured nucleotide stoichiometry of Na4(2'GMP)8. Binding constants for the Etd:disordered 2'GMP complexes were determined to be (1.6 +/- 0.1) x 10(4)M(-1) and 6.3 +/- 0.5 M(-1) at O degrees C and (1.1 +/- 0.2) x 10(4) M(-1) and 18 +/- 11M(-1) for 5'GMP at 5 degrees C for the 1:1 and 1:2 complex, respectively. For the 1:1 and 1:2 2'GMP:Etd species the enthalpies were determined to be -19.8 +/- 1.0 kcal/mole and 0.1 +/- 0.3 kcal/mole, respectively, and the entropies were -53.3 +/- 6.6 eu and 3.9 +/- 1.6 eu, respectively. Binding constants for the Etd: structured 2'GMP complex, assuming a complex with stoichoimetry (Na+)4 (2'GMP)8 for the structured unit, were determined to be (1.9 +/- 0.1) x 10(4)M(-1) and 5.8 +/- 0.6) x 10(2)M(-1), respectively at 0 degrees C.
authors.affiliation: Department of Radiology, St. Elizabeth Hospital Medical Center, Youngstown, Ohio 44501-1790, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Barr
mesh_terms: D004996:Ethidium / Q000737:chemistry*; D006157:Guanosine Monophosphate / Q000737:chemistry*; D007364:Intercalating Agents / Q000737:chemistry*; D007536:Isomerism; D016018:Least-Squares Analysis; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012984:Software; D013816:Thermodynamics
chemical_list: D007364:Intercalating Agents; C026693:2'-guanylic acid; D006157:Guanosine Monophosphate; D004996:Ethidium