sup 1 H NMR studies of tris(phenanthroline) metal complexes bound to oligonucleotides: Characterization of binding modes

Journal Article · Tue Feb 20 04:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00459a006· OSTI ID:6896396

Rehmann, J P; Barton, J K ^[1]

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1. Columbia Univ., New York, NY (USA)

The binding of Ru(phen){sub 3}{sup 2+}, Rh(phen){sub 3}{sup 3+}, and Co(phen){sub 3}{sub 3+} to the oligonucleotides d(GTGCAC){sub 2} and 5{prime}-pd(CGCGCG){sub 2} has been examined by {sup 1}H NMR spectroscopy as a function of temperature, concentration, and chirality of the mental complex. The duplex oligonucleotides act as chiral shift reagents for the metal complexes; phenanthroline protons associated with each enantiomer are resolved upon binding to the oligomer. The spectral titrations, consistent with photophysical studies, indicate that the complexes bind to the oligomer through two modes: one assigned as intercalation favoring the {Delta}-isomer, and the other assigned as the surface-bound interaction favoring the {Lambda}-isomer. The NMR chemical shift variations appear particularly sensitive to surface-bound interaction. With respect to oligonucleotide proton shifts, the adenine H2 proton, positioned in the minor groove of the helix, shows the largest upfield shifts with metal binding, and more dramatically with {Lambda}-isomers. The major groove thymine methyl protons (TMe) shift downfield to a lesser extent, and more so for {Delta}-isomers. In contrast to studies with the substitutionally inert metal complexes, addition of racemic Co(phen){sub 3}{sup 3+} to the oligonucleotide solution yields unequal populations of enantiomers, owing to the rapid racemization of the cobalt complex in the presence of oligomer and reequilibration to that form which favors binding. Duplex melting has also been monitored by {sup 1}H NMR spectroscopy.

• OSTI ID: 6896396
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:7; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AROMATICS
AZAARENES
BARYONS
CHEMICAL REACTIONS
CHEMICAL SHIFT
COBALT COMPLEXES
COMPLEXES
CROSS-LINKING
DNA
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
HADRONS
HETEROCYCLIC COMPOUNDS
MAGNETIC RESONANCE
METALS
NUCLEAR MAGNETIC RESONANCE
NUCLEIC ACIDS
NUCLEONS
OLIGONUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHENANTHROLINES
POLYMERIZATION
PROTONS
RESONANCE
RHODIUM COMPLEXES
RUTHENIUM COMPLEXES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPLEXES