Solution structure and main chain dynamics of the regulatory domain (Residues 1-91) of human cardiac troponin C

Summary, in English

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.

• Author: Kimmo Pääkkönen; Arto Annila; Tia Sorsa; Piero Pollesello; Carola Tilgmann; Ilkka Kilpeläinen; Piia Karisola; Ismo Ulmanen; Torbjörn Drakenberg
• Publishing year: 1998-06-19
• Language: English
• Pages: 15633-15638
• Publication/Series: Journal of Biological Chemistry
• Volume: 273
• Issue: 25
• Links: http://dx.doi.org/10.1074/jbc.273.25.15633
• Document type: Journal article
• Publisher: American Society for Biochemistry and Molecular Biology
• Topic: Cell and Molecular Biology; Medicinal Chemistry
• Status: Published
• ISBN/ISSN/Other: ISSN: 0021-9258