The P5 position refers to {TAIL ~ the amino acid residue} that follows {HEAD ~ the amino acid residue} that occupies the P4 pocket 
The P5 position refers to { TAIL ~ the amino acid residue } that follows { HEAD ~ the amino acid residue } that occupies the P4 pocket
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH