Kathryn

Actually, 4 stranded DNA is VERY stable. It can only be formed by short sequences of guanine bases. Instead of assembling by Watson-Crick base pairing, it assembles via Hoosteen basepairing, so that a ring of 4 guanine bases comprises the base unit. This form of DNA can assemble in a varity of conformations, with both parallel and antiparallel strands, and is thought to play a role in sister chromatid alignment during recombination.