Patent ID: 7723469

Claim:
A method of treating leukemia in a subject comprising administering to a subject in need thereof a therapeutically effective amount of a cross-linked polypeptide, wherein the cross-linked polypeptide has increased cell permeability compared to a corresponding uncrosslinked polypeptide and wherein the cross-linked polypeptide has the formula: wherein; each R 1 and R 2 are independently H, alkyl, alkenyl, alkynyl, arylalkyl, cycloalkyl, heteroarylalkyl, or heterocyclylalkyl; R 3 is alkyl, alkenyl, alkynyl; [R 4 —K—R 4 ] or a naturally occurring amino acid side chain; each of which is substituted with 0-6 R 5 ; R 4 is alkyl, alkenyl, or alkynyl; R 5 is halo, alkyl, OR 6 , N(R 6 ) 2 , SR 6 , SOR 6 , SO 2 R 6 , CO 2 R 6 , R 6 , a fluorescent moiety, or a radioisotope; K is O, S, SO, SO 2 , CO, CO 2 , CONR 6 , or R 6 is H, alkyl, or a therapeutic agent; R 7 is alkyl, alkenyl, alkynyl; [R 4 —K—R 4 ] or a naturally occurring amino acid side chain; each of which is substituted with 0-6 R 5 ; n is an integer from 1-4; x is an integer from 2-10; each y is independently an integer from 0-100; z is an integer from 1-10; and each Xaa is independently an amino acid; wherein the polypeptide has a substantially alpha helical secondary structure in aqueous solution.