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