▁de grad ation ▁by ▁nuc leases . ▁L - R NA ▁apt am ers ▁are ▁considered ▁potential ▁dru gs ▁and ▁are ▁currently ▁being ▁tested ▁in ▁clin ical ▁tri als . ▁ ▁Fe atures ▁ ▁Chem ical ▁properties ▁ ▁L - R NA ▁apt am ers , ▁built ▁using ▁L - ri bose , ▁are ▁the ▁en anti om ers ▁of ▁natural ▁o lig on uc le ot ides , ▁which ▁are ▁made ▁with ▁D - ri bose . ▁N uc le ic ▁acid ▁apt am ers , ▁including ▁L - R NA ▁apt am ers , ▁contain ▁ ▁ad en os ine ▁mon oph osph ate , ▁gu anos ine ▁mon oph osph ate , ▁c yt id ine ▁mon oph osph ate , ▁u rid ine ▁mon oph osph ate , ▁a ▁ph osph ate ▁group , ▁a ▁nucle ob ase ▁and ▁a ▁rib ose ▁sugar . ▁ ▁Bi ological ▁characteristics ▁Like ▁other ▁apt am ers , ▁L - R NA ▁apt am ers ▁are ▁able ▁to ▁bind ▁mole cules ▁such ▁as ▁pe pt ides , ▁prote ins , ▁and ▁subst ances ▁of ▁low ▁mole cular ▁weight . ▁The ▁aff inity ▁of ▁L - R NA ▁apt am ers ▁to ▁their ▁target ▁mole cules ▁often ▁lies ▁in ▁the ▁p ico ▁to ▁nan om olar ▁range ▁and ▁is ▁thus ▁compar able ▁to ▁ant ib od ies . ▁ ▁L - R NA ▁apt am ers ▁themselves ▁have ▁low ▁ant igen icity . ▁In ▁contrast ▁to ▁other ▁apt am ers , ▁L - R