These guanine-rich sequences may stabilize chromosome ends by forming structures of stacked sets of four-base units, rather than the usual base pairs found in other DNA molecules. Here, four guanine bases, known as a guanine tetrad, form a flat plate. These flat four-base units then stack on top of each other to form a stable G-quadruplex structure. These structures are stabilized by hydrogen bonding between the edges of the bases and chelation of a metal ion in the centre of each four-base unit. Other structures can also be formed, with the central set of four bases coming from either a single strand folded around the bases, or several different parallel strands, each contributing one base to the central structure.
these guanine-rich sequences may stabilize chromosome ends by forming structures of stacked sets of four-base units rather than the usual base pairs found in other dna molecules here four guanine bases known as a guanine tetrad form a flat plate these flat four-base units then stack on top of each other to form a stable g-quadruplex structure these structures are stabilized by hydrogen bonding between the edges of the bases and chelation of a metal ion in the centre of each four-base unit other structures can also be formed with the central set of four bases coming from either a single strand folded around the bases or several different parallel strands each contributing one base to the central structure