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Z → B transition in poly[d(G‐m 5 C) 2 ] induced by interaction with 4′,6‐diamidino‐2‐phenylindole
Author(s) -
Kim Seog K.,
Eriksson Svante,
Nordén Bengt
Publication year - 1993
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.360331105
Subject(s) - dapi , chemistry , intercalation (chemistry) , dna , crystallography , molecule , circular dichroism , stereochemistry , base pair , biochemistry , organic chemistry , apoptosis
The Z form of poly[d(G‐m 5 C) 2 ], in presence of Mg 2+ ion, is found to be transformed into B form upon interaction with 4′,6‐diamidino‐2‐phenylindole (DAPI). The Z → B transformation is complete at a mixing ratio of about 0.07 DAPI per DNA base pairs, i.e., each DAPI molecule may be related to the conversion of 6–7 base pairs. An interaction between DAPI and poly[d(G‐m 5 C) 2 ] in its Z form at low drug: DNA ratios is suggested from optical dichroism and time‐resolved luminescence anisotropy results. The spectroscopic behaviour of DAPI indicates that the Z conformation of DNA does not provide normal binding sites for DAPI, such as groove or intercalation sites, but that the initial association may be of external nature. © 1993 John Wiley & Sons, Inc.