A.G. Scientific, Inc. Calpain-1, Porcine Erythrocytes C-1569

Native calpain-1 from porcine erythrocytes. The two major isoforms, calpain I (μ-form) and calpain II (m-form), differ in their calcium requirement for activation. Calpain I requires only micromolar amounts of calcium (ECâ‚…â‚€ = 2 μM), while calpain II requires millimolar amounts (ECâ‚…â‚€ = 1 mM). Calpains are heterodimers of 80 kDa and 30 kDa subunits. The 80 kDa unit has the catalytic site and is unique to each isozyme. The 30 kDa unit is a regulatory subunit and common to both calpain I and calpain II. The 80 kDa unit consists of four domains (I-IV). The 30 kDa unit has two domains (V and VI). • Domain I is partially removed during autolysis. • Domain II is the protease domain. • Domain III exhibits a homology with typical calmodulin binding proteins and interacts with calcium binding domains (IV and VI) and frees domain II for protease activity. • Domain IV is a calcium binding domain. • Domain V contains a hydrophobic region and is essential for calpain interaction with membranes. • Domain VI is a calcium binding domain Specific Activity: ≥1200 units/mg protein. Unit Definition: One unit is defined as the amount of enzyme that will hydrolyze 1 pmol Suc-LLVY-AMC in 1 min at 25°C using the Calpain Activity Assay Kit, Fluorogenic. Note: 1 caseinolytic unit = 9 fluorogenic units