{TAIL ~ The nucleic acid region} of the nucleic acid ligand serve in whole or in part as {HEAD ~ ligands} to a given target 
{ TAIL ~ The nucleic acid region } of the nucleic acid ligand serve in whole or in part as { HEAD ~ ligands } to a given target
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH