The effects of loop size on Sac7d-hairpin DNA interactions

► Hairpin structure is a common feature of DNA molecules. ► Sac7d binding affinity to hairpin DNA is determined by loop size and stem integrity. ► Tetra-loop is the most favorable one for Sac7d-hairpin DNA interaction. ► For Sac7d-stabilized hairpin DNA, the loop region may absorb this torsional stress.