The structural transition and compaction of human telomeric G-quadruplex induced by excluded volume effect under cation-deficient conditions

The structure polymorphism of human telomeric G-cluadruplex (ht-quadruplex) is currently an important topic but remains controversy. Here, we present study of the ht-cluadruplex under the cation-deficient but molecular crowding conditions by circular dichroism (CD), microchip electrophoresis (MCE) and UV-melting experiments. Our results show that with concentration increasing of poly(ethylene glycol) (PEG), the structural transition of ht-quadruplex occurs accompanied by structural compaction and enhanced stabilization, which may be caused by excluded volume effect. This work also demonstrates that htquadruplex can be well assembled without cations and the structure of ht-quadruplex is actually very complex in vivo. (c) 2008 Elsevier B.V. All rights reserved.