Calpain Inhibitor I

Calpain Inhibitor I is a strong, competitive inhibitor of the Ca²⁺-dependent neutral cysteine proteases calpain I and calpain II.

Calpain inhibitor I inhibits calpain, which activates myosin light chain kinase and protein kinase C by partial proteolysis. The inhibitor should be membrane permeable due to low molecular weight and lack of charged residues.
Calpain Inhibitor I is used for western blotting methods.

Calpain Inhibitor I is a strong, competitive inhibitor of the Ca²⁺-dependent neutral cysteine proteases calpain I (requiring 2–75 μM Ca²⁺ for activation) and calpain II (requiring 200–800 μM) with a K_i-value between 0.12 μM and 0.23 μM. Calpain II is inhibited to a lesser extent than calpain I. Calpain Inhibitor I is also a strong inhibitor of papain and cathepsin B and L. It shows only weak inhibition of cathepsin H and α-chymotrypsin and does not inhibit trypsin. ID₅₀ for 0.02 U platelet calpain is 0.05 μM.

Working concentration: 0.1 - 10 μM
The suggested starting concentration is 17 μg/ml. This is the concentration at which half maximal inhibition of calpain I is observed.
Working solution: Recommended solvent is DMF, ethanol, or methanol up to 10 mg/ml.
Storage conditions (working solution): -15 to -25 °C
Solutions in DMF, methanol, ethanol are stable for 4 weeks at -15 to -25 °C.

C₂₀H₃₇N₃O₄

Soluble in DMF, ethanol, or methanol to 10 mg/ml. For a stock solution, Roche recommends dissolving 1 mg of the inhibitor in 100 μl DMF, methanol, or ethanol. Before use, dilute with water or phosphate buffer (0.1 M, pH 7.5) to desired concentration. Solutions in DMF, ethanol, or methanol are stable for 2 to 3 days at 2 to 8 °C, and approximately 4 weeks at -15 to -25 °C. For best results, prepare solutions fresh before use.

Purity: 98% (from C); chromatographically homogeneous

For life science research only. Not for use in diagnostic procedures.