Peptain-1

Peptain-1 is a fragment of the α-crystallin domain of αB-crystallin which like the parent protein has the ability to function as a molecular chaperone.  α-Crystallin is a small heat shock protein consisting of αA- and αB- subunits; αB-crystallin is stress-inducible and is present in several tissues including lens, retina, heart, skeletal muscles and kidney, and αA-crystallin is non inducible and present mainly in lens, where it has a role in lens transparency.  In animal models, intraperitoneal injections of peptain-1 block lens epithelial cell apoptosis and cataract formation and reduce stress-induced apoptosis.  In glaucoma, axonal degeneration and death of retinal ganglion cells (RGCs) are primary causes of vision loss and in rat models peptain-1 significantly decreases hypoxia-induced RGC loss.   Peptain-1 has been used to generate a mouse monoclonal antibody with the aim of blocking the functions of αB-crystallin. The antibody generated specifically reacts with αB-crystallin in human and mouse lens proteins, and is also able to inhibit the chaperone and anti-apoptotic activities of peptain-1.