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