engleski

Optical spectra of wet and dry M-DNA

We present measurements of optical absorption spectra of M-DNA, a form of DNA where divalent metal cations are incorporated into the DNA structure by replacing one of the hydrogens from hydrogen bonds in the interior of a double helix. In our experiment we have used Zn2+ cations which readily form a complex with DNA in alkaline buffers (pH 9). Absorption spectra of wet and dry Zn-DNA are almost identical and show a redshift of absorption maxima. The red energy shift indicates an increase of the pi-pi overlap of adjacent molecular orbitals in a more compact M-DNA structure. However, the effect is smaller (similar to 0.1 eV) than predicted (similar to 1 eV) which we attribute to sequence randomness of native DNA used in the experiment.

NUCLEIC-ACID BASES ; ELECTRONIC-SPECTRA ; ABSORPTION SPECTRA ; ENERGY-TRANSFER ; EXCITED-STATES ; POLYNUCLEOTIDES ; MOLECULES ; NUCLEOTIDES ; TRANSITIONS ; ULTRAVIOLET

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