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Slow exchanging protons in the Z‐form of G‐C and A‐C alternating polymers by using a rapid dialysis method
Author(s) -
Hartmann B.,
Ramstein J.,
Leng M.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81122-5
Subject(s) - polymer , proton , kinetics , chemistry , limiting , dialysis , crystallography , stereochemistry , physics , organic chemistry , mechanical engineering , medicine , quantum mechanics , engineering
Using a dialysis method we have measured the hydrogen exchange (HX) kinetics in poly(dG‐dC)·poly(dG‐dC), poly(dG‐m 5 dC)·poly(dG‐m 5 dC), poly(dG‐br 5 dC)·poly(dG‐br 5 dC) and platinated poly(dA‐br 5 dC)·poly(dG‐dT) under experimental conditions in which these polymers adopt the Z‐conformation. The latter polymer has one slow exchanging proton with a half‐time of about 2 h, whereas the other G‐C alternating polymers display a slow class of two protons with exchange half‐time of about 6 h. These exchange half‐times are independent of ionic strength and of the nature of the salt for all these polymers in the Z‐form. The slow proton exchange appears to be strongly correlated to the Z‐conformation but rather independent of the Z‐DNA sequence. The comparison of the proton exchange rates with the corresponding B⇋Z transition rates is not in favour of the same rate limiting step for both processes.