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