Application Can be used for the determination of chymotrypsin; liberates 4-hydroxy-3-nitrobenzoic acid (also available from Sigma). Biochem/physiol Actions Specific chromogenic inactivator of chymotrypsin. Inhibits anti-IgE-mediated histamine release and inositol trisphosphate (IP3) production in mast cells, possibly by a mechanism involving inhibition of phospholipase C (PLC).1