In {TAIL ~ other embodiments}, {HEAD ~ X2} is selected from D leucine, D valine, glycine and D proline 
In
In { TAIL ~ other embodiments } , { HEAD ~ X2 } is selected from D leucine , D valine , glycine and D proline
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH