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The europium (III)‐induced conformational transitions of poly(dG‐dC) · poly(dG‐dC) and poly(dG‐m 5 dC) · poly(dG‐m 5 dC) as studied by europium(III) luminescence, UV, and CD spectroscopy
Author(s) -
Klakamp Scott L.,
Horrocks William Dew.
Publication year - 1990
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.360300106
Subject(s) - chemistry , polynucleotide , europium , excited state , ion , excitation , crystallography , analytical chemistry (journal) , stereochemistry , atomic physics , physics , organic chemistry , biochemistry , quantum mechanics
The Eu 3+ ion induces a B to Z transition in poly(dG‐dC) · poly(dG‐dC) and poly(dG‐m 5 dC) · poly(dG‐m 5 dC). Other conformations were also elicited by this ion. The conformational changes of these polynucleotides were followed by CD and uv spectroscopy. Eu 3+ excitation spectra and Eu 3+ excited‐state lifetimes were measured for the Eu 3+ ion bound to the duplexes in various conformations. B‐form poly(dG‐dC) and poly(dG‐m 5 dC) appear to have a single class of the Eu 3+ binding site while the Z‐form observed conformation exhibits two. The numbers of H 2 O molecules coordinated to the Eu 3+ ion bound to the various conformations of the duplexes were determined by measuring Eu 3+ excited‐state lifetimes in H 2 O and D 2 O. The first‐order rate constants for the Eu 3− and [Co(NH 3 ) 6 ] 3+ induced B to Z transitions were measured. The Eu 3+ mediated conversion is much faster than the [Co(NH 3 ) 6 ] 3+ induced conversion in both polynucleotides.