Inhibition of mutant troponin C activity by an intra-domain disulphide bond.

Triggering of contraction in striated muscles involves a conformational transition in the N-terminal domain of troponin C, the calcium-binding component of thin filaments. We have designed a mutant troponin C in which the key conformational transition and the calcium-regulatory activity are reversibly blocked by the formation of a disulphide bridge. Our results may be applicable to other proteins of the same family of calcium-binding proteins.