Biopolymers and cell. 2008; 24 (1): 69 - 77

Detection of two different protonated forms of poly(C) by electrophoresis method

M. I. Zarudnaya, A. V. Stepanyugin, A. L. Potyahaylo, D. M. Hovorun

Conformational transitions in poly(C) as a function of pH have been first studied by the method of electrophoresis. It was found that the polymer migrates by two overlapping bands at acidic pH. Occurrence of two overlapping bands was not due to specific action of the solvent and the band with lower electrophoretic mobility did not correspond to «frozen» form of the polymer, similar to that of poly(A). It was proposed that the band with higher electrophoretic mobility corresponds to double helical form and with lower electrophoretic mobility corresponds to four-stranded i-motif. The dependence of occurrence of two zones of protonated poly(C) on ionic strength was studied in the range of concentrations 4–74 mM. The scheme of i-motif formation from duplexes and single strands has been suggested.

Keywords: poly(C), protonation, conformational transitions, i-motif, electrophoresis.