Physical Properties of Calpain and Calpastatin

Properties of the Calpains

Property	Autolyzed µ-calpain	µ-Calpain	Autolyzed m-Calpain	m-Calpain
Molecular Mass¹	99,292	110,188	98,530	108,304
Molecular Mass, large subunit¹	78,914	81,890	78,152	80,006
Molecular Mass, small subunit¹	20,396	28,316	20,396	28,316
pH optimum²	7.6	7.5	7.4	7.6
[Ca²⁺] for half-maximal activity³	0.6-22.0	1-100	5-180	91-2500
[Ca²⁺] for binding Calpastatin⁴	0.042µM	42µM	24µM	400µM
Theoretical pI¹	5.31	5.36	4.90	4.94

¹Calculated using the Compute pI/Mw tool on the Expasy web site (http://ca.expasy.org/tools/pi_tool.html) and the human calpain sequences.

²Edmunds, T, Nagainis, PA, Sathe, SK, Thompson, VF, and Goll, DE (1991) Biochimica et Biophysica Acta, 1077, 197-208.

³Goll, DE, Kleese, WC, Kumamota, T, Cong, J, and Szpacenko, A (1989) In "Intracellular Proteolysis: Mechanisms and Regulation" (Katunuma, N and Kominami, E, eds.) Japan Scientific societies Press, Tokyo, Japan. pp. 80-91.

⁴Kapprell, H-P and Goll, DE (1989) J. Biol. Chem., 264, 17888-17896.

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This page was last updated on 25 September 2001 .