Unusual Isothermal Hysteresis in DNA i-Motif pH Transitions: A Study of the RAD17 Promoter Sequence.

ABSTRACT: We have interrogated the isothermal folding behavior of the DNA i-motif of the human telomere, dC₁₉, and a high-stability i-motif-forming sequence in the promoter of the human DNA repair gene RAD17 using human physiological solution and temperature conditions. We developed a circular-dichroism-spectroscopy-based pH titration method that is followed by analysis of titration curves in the derivative domain and found that the observed pH-dependent folding behavior can be significantly different and, in some cases, multiphasic, with a dependence on how rapidly i-motif folding is induced. Interestingly, the human telomere sequence exhibits unusual isothermal hysteresis in which the unfolding process always occurs at a higher pH than the folding process. For the RAD17 i-motif, rapid f

SUBMITTER: Rogers RA 

PROVIDER: S-EPMC5937167 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature