Solution structure and main chain dynamics of the regulatory domain (Residues 1-91) of human cardiac troponin C
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Thee three-dimensional structure of calcium-loaded regulatory, i.e. N- terminal, domain (1-91) of human cardiac troponin C (cNTnC) was determined by NMR in water/trifluoroethanol (91:9 v/v) solution. The single-calcium-loaded cardiac regulatory domain is in a 'closed' conformation with comparatively little exposed hydrophobic surface. Difference distance matrices computed from the families of Ca2+-cNTnC, the apo and two-calcium forms of the skeletal TnC (sNTnC) structures reveal similar relative orientations for the N, A, and D helices. The B and C helices are closer to the NAD framework in Ca2+-cNTnC and in apo-sNTnC than in 2-Ca2+sNTnC. However, there is an indication of a conformational exchange based on bread 15N resonances for several amino acids measured at several temperatures. A majority of the Amides in the α-helices and in the calcium binding loop exhibit very fast motions with comparatively small amplitudes according to the LipariSzabo model. A few residues at the N and C termini are flexible. Data were recorded from nonlabeled and 15N-labeled samples, and backbone dynamics was investigated by 15N T1, T2, and heteronuclear nuclear Overhauser effect as well as by relaxation interference measurements.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|Publication status||Published - 1998 Jun 19|