▁focused ▁on ▁using ▁the oph yll ine ▁as ▁the ▁lig and . ▁ ▁In ▁these ▁studies ▁an ▁R NA ▁hair pin ▁is ▁formed ▁which ▁blocks ▁the ▁rib os ome ▁binding ▁site , ▁thus ▁in hib iting ▁translation . ▁ ▁In ▁the ▁presence ▁of ▁the ▁lig and , ▁in ▁these ▁cases ▁the oph yll ine , ▁the ▁regul atory ▁R NA ▁region ▁is ▁cle aved ▁off , ▁allowing ▁the ▁rib os ome ▁to ▁bind ▁and ▁translate ▁the ▁target ▁gene . ▁Much ▁of ▁this ▁R NA ▁engineering ▁work ▁was ▁based ▁on ▁rational ▁design ▁and ▁previously ▁determined ▁R NA ▁structures ▁rather ▁than ▁directed ▁evolution ▁as ▁in ▁the ▁above ▁examples . ▁More ▁recent ▁work ▁has ▁bro aden ed ▁the ▁lig ands ▁used ▁in ▁rib oz yme ▁rib os w itch es ▁to ▁include ▁th ym ine ▁py roph osph ate ▁( 2 ). ▁Fl u ores c ence - activ ated _ cell _ sort ing ▁has ▁also ▁been ▁used ▁to ▁engineering ▁apt az ym es . ▁ ▁App lications ▁▁ ▁Rib oz ym es ▁have ▁been ▁proposed ▁and ▁developed ▁for ▁the ▁treatment ▁of ▁disease ▁through ▁gene ▁ther apy ▁( 3 ). ▁One ▁major ▁challenge ▁of ▁using ▁R NA ▁based ▁en zym es ▁as ▁a ▁th era pe ut ic ▁is ▁the ▁short ▁half - life ▁of ▁the ▁catal yt ic ▁R NA ▁mole cules ▁in ▁the ▁body . ▁ ▁To ▁combat ▁this , ▁the ▁ 2 ’ ▁position ▁on ▁the ▁rib ose ▁is ▁modified ▁to ▁improve ▁R NA ▁stability . ▁ ▁One ▁area ▁of ▁rib oz