Conformational properties of Ca2+-binding segments of proteins from the troponin C superfamily.
The troponin C superfamily consists of about 100 Ca2+-binding proteins. Sequence variations observed in these proteins have been analyzed and lead to the following conclusions. (1) There are some strict rules defining the set of calcium ligands necessary for effective Ca2+ binding. (2) If they are fulfilled, the Ca2+ binding constant depends on tertiary interactions within a protein, as well as the free energy of secondary structures of its polypeptide chain. The former provide a constant contribution to the free energy of protein folding and the Ca2+-binding process. (3) The observed variety in Ca2+-binding constants of these proteins results from the various abilities of segments of these proteins to assume the correct secondary structure.
Boguta
G
G
Department of Biophysics, University of Warsaw, Poland.
Bierzyński
A
A
D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D011487:Protein Conformation; D014336:Troponin / Q000378:metabolism*; D019209:Troponin C
D014336:Troponin; D019209:Troponin C; D002118:Calcium