2Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, ul. Institutskaya 3, 142290 Pushchino, Moscow Region, Russia
3Institute of Bioorganic Chemistry, Pushchino Branch, Russian Academy of Sciences, pr. Nauki 6, 142290 Pushchino, Moscow Region, Russia
* To whom correspondence should be addressed.
Received June 20, 2007; Revision received August 6, 2007
We show that an enzyme exists in rat brain capable of cleaving the caspase-3 specific peptide substrate Ac-DEVD-AMC at low pH. The enzyme shows properties of a cysteine protease and is localized, predominantly, in lysosomes. We have purified this enzyme from rat brain and identified it by MALDI-TOF MS. The enzyme possessing acidic DEVDase activity in rat brain appears to be cathepsin B. It remains obscure, whether cathepsin B participates in cleavage of caspase-3 substrates in vivo. We suggest that under certain conditions (e.g. in hypoxia) cathepsin B participates in cleavage of caspase-3 substrates in brain cells.
KEY WORDS: caspase-3, cathepsin B, Ac-DEVD-AMC