The method also allows for the identification of nucleic acids that have facilitating activities as measured by {HEAD ~ their ability} to facilitate {TAIL ~ formation} of a covalent bond between the nucleic acid, including its associated functional unit, and its target 
The method also allows for the identification of nucleic acids that have facilitating activities as measured by { HEAD ~ their ability } to facilitate { TAIL ~ formation } of a covalent bond between the nucleic acid , including its associated functional unit , and its target
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH