10.1007/s10541-008-3014-5

Abstract

332Abbreviations: AMC) 7 amino 4 methylcoumarin; CA 074) N [L 3 trans (propylcarbamoyl)oxirane 2 carbonyl] L isoleucyl L proline; DTT) dithiothreitol; MALDI TOF MS) matrix assisted laser desorption/ionization with time of flight mass spectrometry. Abstract-Weshow 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 activ ity in rat brain appears to be cathepsin B. It remains obscure, whether cathepsin B participates in cleavage of caspase 3 sub strates in vivo. We suggest that under certain conditions (e.g. in hypoxia) cathepsin B participates in cleavage of caspase 3 substrates in brain cells.