Open AccessInteraction of mithramycin with DNA
Author(s) -
DEMICHELI Cynthia,
ALBERTINI JeanPaul,
GARNIERSUILLEROT Arlette
Publication year - 1991
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1991.tb16020.x
Subject(s) - dimer , deprotonation , chemistry , crystallography , dna , aqueous solution , stereochemistry , binding constant , fluorescence , ion , binding site , organic chemistry , biochemistry , physics , quantum mechanics
The CD and fluorescence properties of mithramycin have been used to follow its complexation to cations such as Mg 2+ and Zn 2+ and the binding of these complexes to DNA. At low concentration (< 2 μM) in aqueous solution, mithramycin is always in the dimeric state, the conformation of the dimer being either a right‐handed screw when the dimer is neutral, or a left‐handed screw when the dimer is negatively charged. In the deprotonated state the dimer can bind one cation forming a complex [M 2+ (Mit − ) 2 ] which has a right‐handed screw conformation. The stability constants of the complex at 37°C in 0.1 M KCl are 4 × 10 5 and 1 × 10 6 for Mg 2+ and Zn 2+ , respectively. The complex in the right‐handed screw conformation binds DNA. In this case the stability constants of the complex [M 2+ (Mit − ) 2 ] increase and are 3.6 × 10 6 and 1.2 × 10 7 for Mg 2+ and Zn 2+ , respectively.