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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1981-9-25
pubmed:abstractText
The effect of Ca2+ binding on the 270-MHz proton nuclear magnetic resonance spectrum of bovine cardiac troponin C (cTnC) has been examined. Assignment of resonances in the aromatic spectral region to tyrosine residues 10, 111, and 150 has been made for apo-cTnC and calcium-bound cTnC on the basis of decoupling experiments, pH titrations, temperature-induced changes, and gadolinium broadening experiments. The sequence homology which these tyrosine residues display with residues in two previously studied proteins, rabbit skeletal troponin C (sTnC) [Seamon, K. B., Hartshorne, D. J., & Bothner-By, A. A. (1977) Biochemistry 16, 4039] and bovine brain calmodulin [Seamon, K. B. (1980) Biochemistry 19, 207], was also used in assignments. High-affinity calcium binding (up to 2 mol/cTnC) causes large alterations in the environments of tyrosines-10 and -150, indicating that the N terminus is probably buried in the protein interior. The evidence suggests that the environment of tyrosine-150 in calcium-saturated cTnC must closely resemble that of tyrosine-138 in calmodulin in that it experiences the hydrophobic core of the protein. However, there is no similarity between these environments in the apoproteins. Dramatic alterations in phenylalanine resonances are seen during the binding of the third mole of calcium, corresponding to filling the sole low affinity site. Comparison of the spectral calmodulin reveals many structural similarities which stem from their high degree of primary sequence homology.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
20
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3286-92
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1981
pubmed:articleTitle
Hydrogen-1 nuclear magnetic resonance investigation on bovine cardiac troponin C. Comparison of tyrosyl assignments and calcium-induced structural changes to those of two homologous proteins, rabbit skeletal troponin C and bovine brain calmodulin.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't