Variable-temperature size exclusion chromatography for the study of the structural changes in G-quadruplex

Abstract

The conformational equilibria of a guanine-rich sequence found at the promoter region of the human c-kit oncogene are studied by means of circular dichroism spectroscopy (CD) and variable-temperature Size Exclusion Chromatography (SEC). It is shown that the wild sequence ckit21 exists as a mixture of monomeric and multimeric G-quadruplex. Appropriate mutation of several bases in the wild sequence produces the shift from parallel to antiparallel G-quadruplex, as well as the disappearance of multimeric species. The shift from the antiparallel to the parallel conformation induced by temperature is reflected in both CD and SEC profiles.