5TNC

REFINED CRYSTAL STRUCTURE OF TROPONIN C FROM TURKEY SKELETAL MUSCLE AT 2.0 ANGSTROMS RESOLUTION


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Observed: 0.155 

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This is version 1.3 of the entry. See complete history


Literature

Refined crystal structure of troponin C from turkey skeletal muscle at 2.0 A resolution.

Herzberg, O.James, M.N.

(1988) J Mol Biol 203: 761-779

  • DOI: https://doi.org/10.1016/0022-2836(88)90208-2
  • Primary Citation of Related Structures:  
    5TNC

  • PubMed Abstract: 

    The crystal structure of troponin C from turkey skeletal muscle has been refined at 2.0 A resolution (1 A = 0.1 nm). The resulting crystallographic R factor (R = sigma[[Fo[-[Fc[[/sigma[Fo[, where [Fo[ and [Fc[ are the observed and calculated structure factor amplitudes) is 0.155 for the 8054 reflections with intensities I greater than or equal to 2 sigma(I) within the 10 A to 2.0 A resolution range. With 66% of the residues in helical conformation, troponin C provides a good sample for helix analysis. The mean alpha-helix dihedral angles (phi, psi = -62 degrees, -42 degrees) agree with values observed for helical regions in other proteins. The helices are all curved and/or kinked. In particular, the 31 amino acid long inter-domain helix is smoothly curved, with a rather large radius of curvature of 137 A. Helix packing is different in the Ca2+-free domain (N-terminal) and the Ca2+-bound domain (C-terminal). The inter-helix angles for the two helix-loop-helix motifs in the regulatory domain are 133 degrees and 151 degrees, whereas the value for the two motifs in the C-terminal domain is 110 degrees, as observed in the EF-hands of parvalbumin. These differences affect the packing of the respective hydrophobic cores of each domain, in particular the disposition of aromatic rings. Pairwise arrangement of Ca2+-binding loops is common to both states, but the conformation is markedly different. Conversion of one to the other can be achieved by small cumulative changes of main-chain dihedral angles. The integrity of loop structure is maintained by numerous electrostatic interactions. Both salt bridges and carboxyl-carboxylate interactions are observed in TnC. There are more intramolecular (9) than intermolecular (1) salt bridges. Carboxyl-carboxylate interactions occur because the pH of the crystals is 5.0 and there is a multitude of aspartate and glutamate residues. One is intramolecular and four are intermolecular. Polar side-chain interactions occur more commonly with main-chain carbonyls and amides than with other polar side-chains. These interactions are mostly short range, and are similar to those observed in other proteins with one exception: negatively charged side-chains interact more frequently with main-chain carbonyl oxygen atoms. However, out of 19 such interactions, 10 involve oxygen atoms of the Ca2+ ligands. These unfavorable interactions are compensated by the favorable interactions with the Ca2+ ions and with main-chain amides. They are a trivial consequence of the tight fold of the Ca2+-binding loops.


  • Organizational Affiliation

    Medical Research Council of Canada Group, University of Alberta, Edmonton.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
TROPONIN-C162Meleagris gallopavoMutation(s): 0 
UniProt
Find proteins for P10246 (Meleagris gallopavo)
Explore P10246 
Go to UniProtKB:  P10246
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP10246
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download Ideal Coordinates CCD File 
B [auth A],
C [auth A]
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Observed: 0.155 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 66.55α = 90
b = 66.55β = 90
c = 60.91γ = 120
Software Package:
Software NamePurpose
PROLSQrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1988-10-09
    Type: Initial release
  • Version 1.1: 2008-03-03
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-03-06
    Changes: Data collection, Database references, Derived calculations, Other