Obtustatin

Obtustatin is a 41 amino acid disintegrin peptide isolated from the venom of the Vipera lebetina obtusa. It is a potent (IC50 = 2 nM) and selective inhibitor of the binding of α1β1 integrin to collagen IV. Contrary to other known disintegrins, it does not contain the classical RGD sequence. Obtustatin does not show inhibitory activity toward other integrins, including α2β1, αIIbβ3, αvβ3, α4β1, α5β1, α6β1, and α9β1, α4β7 integrins. Obtustatin potently inhibits angiogenesis in chicken and in mouse model and reduces tumor development by half.