Moss Catherine X, Westrop Gareth D, Juliano Luiz, Coombs Graham H, Mottram Jeremy C
Wellcome Centre for Molecular Parasitology and Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
FEBS Lett. 2007 Dec 11;581(29):5635-9. doi: 10.1016/j.febslet.2007.11.009. Epub 2007 Nov 20.
Metacaspases are cysteine peptidases that are distantly related to the caspases, for which proteolytic processing is central to their activation. Here, we show that recombinant metacaspase 2 (MCA2) from Trypanosoma brucei has arginine/lysine-specific, Ca(2+)-dependent proteolytic activity. Autocatalytic processing of MCA2 occurred after Lys55 and Lys268; however, this was shown not to be required for the enzyme to be proteolytically active. The necessity of Ca(2+), but not processing, for MCA2 enzymatic activity clearly distinguishes MCA2 from the caspases and would be consistent with different physiological roles.
类半胱天冬酶是与半胱天冬酶有远亲关系的半胱氨酸肽酶，其激活过程中蛋白水解加工起着核心作用。在此，我们表明来自布氏锥虫的重组类半胱天冬酶2（MCA2）具有精氨酸/赖氨酸特异性、Ca(2+)依赖性蛋白水解活性。MCA2在Lys55和Lys268之后发生自催化加工；然而，已证明这并非该酶具有蛋白水解活性所必需的。Ca(2+)而非加工过程对MCA2酶活性的必要性，明显将MCA2与半胱天冬酶区分开来，这与不同的生理作用是一致的。
