title: Slow exchanging protons in the Z-form of G-C and A-C alternating polymers by using a rapid dialysis method.
abstract: Using a dialysis method we have measured the hydrogen exchange (HX) kinetics in poly(dG-dC).poly(dG-dC), poly(dG-m5dC).poly(dG-m5dC), poly(dG-br5dC).poly(dG-br5dC) and platinated poly(dA-br5dC).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 in equilibrium Z transition rates is not in favour of the same rate limiting step for both processes.
authors.affiliation: Centre de Biophysique Moléculaire, Orleans, France.
authors.forename: B
authors.initials: B
authors.lastname: Hartmann
authors.forename: J
authors.initials: J
authors.lastname: Ramstein
authors.forename: M
authors.initials: M
authors.lastname: Leng
mesh_terms: D002942:Circular Dichroism; D002945:Cisplatin / Q000031:analogs & derivatives; D003956:Dialysis; D007700:Kinetics; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides; D011522:Protons; D013053:Spectrophotometry
chemical_list: D011089:Polydeoxyribonucleotides; D011522:Protons; C032799:chlorodiethylenetriamine platinum; C019530:poly(dC-dG); C029988:poly(dG-m(5)dC).poly(dG-m(5)dC); D002945:Cisplatin