Calpastatin simultaneously binds four calpains with different kinetic constants.

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Hanna RA, Garcia-Diaz BE, Davies PL

Calpastatin simultaneously binds four calpains with different kinetic constants.

FEBS Lett. 2007 Jun 26;581(16):2894-8. Epub 2007 May 25.

PubMed ID
17543955 [ View in PubMed
]
Abstract

Calpastatin is the endogenous, specific protein inhibitor of the calcium-dependent protease, calpain. Using an active site knock-out m-calpain mutant we have studied the enzyme's calcium-dependent binding to calpastatin by surface plasmon resonance without the complication of proteolysis. Calpastatin was capable of simultaneously binding four molecules of calpain. Its four inhibitory domains (CAST1, 2, 3, and 4) were individually expressed in Escherichia coli and the kinetics of their interaction with calpain was separately compared. Their K(d) values ranged from picomolar to nanomolar in the order CAST1>4>3>2. They have similar k(on) values but the k(off) values ranged over three orders of magnitude and can account for the differences in affinity.

DrugBank Data that Cites this Article

Drug Targets
DrugTargetKindOrganismPharmacological ActionActions
CalciumCalpastatinProteinHumans
Unknown
Not AvailableDetails