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Enantioselective interactions of inversion‐labile trigonal iron(II) complexes upon binding to DNA
Author(s) -
Härd Torleif,
Nordén Bengt
Publication year - 1986
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360250704
Subject(s) - chemistry , enantiomer , dna , enantioselective synthesis , diastereomer , stereochemistry , crystallography , catalysis , organic chemistry , biochemistry
We studied the interactions of the substitution‐inert inversion‐labile complexes Fe(bipy) 3 2+and Fe(phen) 3 2+[and the inversion‐stable complex Ru(bipy) 3 2+ ] with DNA. The association of these complexes to DNA is mainly electrostatic, and Fe(phen) 3 2+shows a more effective binding to DNA than the two bipyridyl complexes, possibly owing to a different binding mode. The interactions are enantioselective, leading to a Pfeiffer shift in the diastereomeric inversion equilibria and an excess of the Δ‐enantiomer of Fe(phen) 3 2+and Fe(bipy) 3 2+ , which is directly monitorable through CD. The partition constants for the inversion equilibrium range from 1.3 to 2.0 for Fe(bipy) 3 2+and Fe(phen) 3 2+ , depending on ionic conditions. From flow LD information about the orientation of the complexes on DNA was obtained: it is consistent with a fit of the Δ‐enantiomer in the major groove of the right‐handed DNA helix. The mechanisms of interaction are discussed against equilibrium, spectroscopic, and kinetic data.