In certain embodiments, X5 is selected from {HEAD ~ D leucine}, D isoleucine, {TAIL ~ D alanine}, D proline and D lysine 
In certain embodiments , X5 is selected from { HEAD ~ D leucine } , D isoleucine , { TAIL ~ D alanine } , D proline and D lysine
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH