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Crystallization and X-ray crystallographic analysis of m-calpain, a Ca2+-dependent protease
C M Hosfield1, Q Ye, J S Arthur
1The Protein Engineering Network of Centres of Excellence and Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Abstract:
The absolute requirement of Ca(2+) for proteolytic activity is a feature unique to the calpains, a family of heterodimeric cysteine proteases. Conditions are described which give rise to diffraction-quality crystals of m-calpain in two crystal forms, P1 and P2(1). Data have been collected from native crystals of m-calpain in both P1 and P2(1) forms, to 2.6 and 2.15 A, respectively. Selenomethionine-containing crystals have been grown in both forms, and anomalous data from the P2(1) selenomethionine enzyme provided the location of 17 of the 19 Se atoms in the protein.