Crystallization and preliminary X‐ray analysis of the Ca 2+ ‐bound C‐terminal lobe of troponin C in complex with a troponin I‐derived peptide fragment from Akazara scallop

Troponin C (TnC) is the Ca 2+ ‐binding component of troponin and triggers muscle contraction. TnC of the invertebrate Akazara scallop can bind only one Ca 2+ at the C‐terminal EF‐hand motif. Recombinant TnC was expressed in Escherichia coli , purified, complexed with a 24‐residue synthetic peptide derived from scallop troponin I (TnI) and crystallized. The crystals diffracted X‐rays to 1.80 Å resolution and belonged to space group P 2 1 2 1 2 1 , with unit‐cell parameters a = 32.1, b = 42.2, c = 60.0 Å. The asymmetric unit was assumed to contain one molecular complex of the Akazara scallop TnC C‐lobe and TnI fragment, with a Matthews coefficient of 1.83 Å 3  Da −1 and a solvent content of 33.0%.