We also observe high kinetic barriers for G4 unfolding \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}$(\Delta G_U^\ddagger \sim 15 - 18\,{k_B}T)$\end{document} that allow kinetic trapping of folded G4 structures. These thermodynamic features may explain the pronounced structural polymorphism of the G4s, as a result of kinetic partitioning, involving several marginally stable folded G4 conformations.