In {TAIL ~ certain embodiments}, {HEAD ~ X4} is selected from D proline, D arginine and D phenylalanine 
In
In { TAIL ~ certain embodiments } , { HEAD ~ X4 } is selected from D proline , D arginine and D phenylalanine
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH