Patent ID: 8609610

Claim:
A peptide-based inhibitor of the proteasome β2/β21 site comprising the structure: (Y)-(X4)-X3-X2-X1 (SEQ ID NO:2), wherein X1 is Phe residue or an aminosubstituted phenylalanine derivative wherein said residue or derivative comprises a carboxy-terminal epoxyketone or vinyl sulfone warhead; X2 is Leu or Ser; X3 is Leu, Val, Ser, Arg, His, Lys, Phe or an aminosubstituted phenylalanine derivative; X4 is present or absent and when present is Phe; Y is present or absent and when present is a capping group; and wherein each aminosubstituted phenylalanine derivative has a structure: wherein X is independently N, C—NH 2 , or C—CH 2 —NH 2 .