A 27-amino-acid synthetic peptide corresponding to the NH ₂-terminal zinc-binding domain of endostatin is responsible for its antitumor activity

The first recombinant endostatin that elicited strong anti-tumor activity was expressed in Escherichia coli and administered as a suspension. Under these conditions, the protein retained its full antiangiogenic activity. Lack of requirement for a folded structure prompted us to investigate antitumor properties of synthetic peptides corresponding to different regions of endostatin. Here, we show that the entire antitumor, antimigration, and antipermeability activities of endostatin are mimicked by a 27-amino-acid peptide corresponding to the NH₂-terminal domain of endostatin. This peptide contains three histidines that are responsible for zinc binding. Mutations of the zinc-binding histidines abolished its anti-tumor and antimigration activities, but not antipermeability properties.