Double-ended zipper model of DNA hybridization. a) Duplex can only open and close from the ends in a zipper-like fashion. Between the two zipper fork positions k and l, the duplex is closed. is the sum over all closed NN parameters in the bound duplex section. b) One MM affects two NN pairs.
Trapp et al. BMC Biophysics 2011 4:20 doi:10.1186/2046-1682-4-20