Proteolysis of Peptide Dendrimers

The ability of proteins and peptides to undergo proteolysis is essential to their biological function. Herein, we report the first detailed study of the protease reactivity of peptide dendrimers. Dendrimers are regularly ramified, tree-like synthetic macromolecules with promising application in technology and medicine. Using trypsin and alpha-chymotrypsin cleavage sites as models, we show that the protease reactivity of peptide dendrimers can be controlled by the degree of branching. Dendrimers with two or three amino acids between branching points were readily cleaved by trypsin irrespective of the position of the reactive sequence within the dendrimers, for example in D1, (Ac-Gly-Phe-Pro)(4)(Dap-Hyp-Arg(down arrow)Met)(2)Dap-Ser-Gly-beta Ala-NH2, and D12, (Ac-Ser-Ala)(8)(Dap-Ala-Arg(down arrow))(4)(Dap-Ala-Asp)(2)Dap-Phe-Ala-Lys*-NH2 (Dap: (S)-2,3-diaminopropionic acid branching point, Hyp: hydroxyproline, Lys*: FITC-labeled lysine (down arrow): cleavage site). On the other hand cleavage was blocked in more compact dendrimers with only one amino acid between branching points, for example in D18B, (Ac-Glu)(8)(Dap-Phe)(4)(Dap-Arg)(2)(Dap-Leu-NH2). The control of proteolysis by topology provides a novel possibility to tune the biological properties of peptide dendrimers not available in linear peptides, and should be generally useful for their use as functional biomolecule analogues, for example, in the context of drug delivery applications.