Peptides whose uptake by cells is controllable
View Patent ↗A generic structure for the peptides of the present invention includes A-X-B-C, where C is a cargo moiety, the B portion includes basic amino acids, X is a cleavable linker sequence, and the A portion includes acidic amino acids. The intact structure is not significantly taken up by cells; however, upon extracellular cleavage of X, the B-C portion is taken up, delivering the cargo to targeted cells. Cargo may be, for example, a contrast agent for diagnostic imaging, a chemotherapeutic drug, or a radiation-sensitizer for therapy. Cleavage of X allows separation of A from B, unmasking the normal ability of the basic amino acids in B to drag cargo C into cells near the cleavage event. X is cleaved extracellularly, preferably under physiological conditions. D-amino acids are preferred for the A and B portions, to minimize immunogenicity and nonspecific cleavage by background peptidases or proteases.
1. A molecule comprising Formula (I):
Q-A-X-B-C Formula (I)
wherein:
C is a fluorescent cargo moiety,
B is a peptide comprising 5 to 20 basic amino acids which is suitable for cellular uptake,
Q is a quencher moiety that quench the fluorescence of C,
A is a peptide comprising 5 to 9 consecutive acidic amino acids, wherein the amino acids are selected from: aspartates and glutamates, and
X is a linker.
2. The molecule of claim 1 , wherein A has a sequence comprising 8 consecutive glutamates.
3. The molecule of claim 1 , wherein B has a sequence comprising 9 to 16 consecutive arginines.
4. The molecule of claim 1 , wherein B has a sequence comprising 9 consecutive arginines.
5. The molecule of claim 1 , wherein B has a sequence comprising 8 arginines.
6. The molecule of claim 1 , wherein (a) A has a sequence comprising 8 to 9 consecutive glutamates and (b) B has a sequence comprising 9 consecutive arginines.
7. The molecule of claim 1 , wherein A and B comprise D-amino acids.
8. The molecule of claim 1 , wherein X is a cleavable linker.
9. The molecule of claim 1 , wherein X is a pH-sensitive linker.
10. The molecule of claim 1 , wherein X is cleaved in the extracellular space.
11. The molecule of claim 1 , wherein X is cleaved by a protease, a matrix metalloproteinase, or a combination thereof.
12. The molecule of claim 1 , wherein X comprises a peptide linkage.
13. The molecule of claim 1 , wherein X comprises aminocaproic acid.
14. The molecule of claim 1 , wherein X comprises a disulfide linkage.
15. The molecule of claim 1 , wherein X is about 6 to about 30 atoms in length.
16. The molecule of claim 1 , wherein X is cleaved by a reducing agent.