pNA (4-nitroaniline)-derived caspase substrates are widely used for the colorimetric detection of various caspase activities. Cleavage of pNA peptides by caspases generates pNA that is monitored colorimetrically at ~405 nm. pNA has maximum absorption around 408 nm.
Caspase-1 substrate with Km = 18 uM and kcat = 0.5 M-1s-1; Caspase-3 substrate with Km = 11 uM and kcat = 2.4 M-1s-1;Caspase-4 substrate with Km = 32 uM and kcat = 0.05 M-1s-1 Caspase-6 substrate with Km = 180 uM and kcat = 0.6 M-1s-1 ; Caspase-7 substrate with Km = 12 uM and kcat = 0.4 M-1s-1; Caspase-8 substrate with Km = 167 uM
Grutter MG (2000). Caspases: key players in programmed cell death. Curr Opin Struct Biol 10, 649-55; Gastman BR (2001). Apoptosis and its clinical impact. Head Neck 23, 409-25; Grutter MG (2000). Caspases: key players in programmed cell death. Curr Opin Struct Biol 10, 649-55; Stennicke HR and Salvesen GS (1999). Catalytic properties of the caspases. Cell Death Differ 6, 1054-9; Stennicke HR and Salvesen GS (1998). Properties of the caspases. Biochim Biophys Acta 1387, 17-31; Thornberry NA and Lazebnik Y (1998). Caspases: enemies within. Science 281, 1312-6; Talanian RV, et al. (1997). Substrate specificities of caspase family proteases. J Biol Chem 272, 9677-82; Fassy F, et al. (1998). Enzymatic activity of two caspases related to interleukin-1beta-converting enzyme. Eur J Biochem 253, 76-83; Datta R, et al. (1996). Activation of the CPP32 protease in apoptosis induced by 1-?-D-arabinofuranosylcytosine and other DNA-damaging agents. Blood 88, 1936-43; Koeplinger KA, et al. (2000). Caspase 8: an efficient method for large-scale autoactivation of recombinant procaspase 8 by matrix adsorption and characterization of the active enzyme. Protein Expr Purif 18, 378-87.