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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
5
|
| pubmed:dateCreated |
1979-8-16
|
| pubmed:abstractText |
Ca2+ binding to pig cardiac myosin, subfragment-1 (S-1), and g2 light chain were investigated by the equilibrium dialysis method. Two different S-1s, one of which can bind Ca2+ and another which cannot, were prepared. In order to calculate the free Ca2+ concentrations adequately, the amounts of Ca2+ included in various chemicals and proteins were measured by atomic absorption spectroscopy. Ca2+ contamination was greatest in KCl among the chemicals tested. In addition, the Ca2+ strongly bound to myosin and S-1 was released in the presence of Mg2+. When Mg2+ was not added, the Ca2+-binding constant of myosin was 4 x 10(5) M-1 and the maximum binding number was 1.8 mol per mol of myosin. Cooperativity between the 2 Ca2+ bindings could not be demonstrated. Mg2+ strongly inhibited the Ca2+ binding: at a free Ca2+ concentration of 1 x 10(-5) M, 1.3 mol Ca2+ was bound to myosin in the absence of Mg2+, but 0.6 and 0.2 mol were bound in the presence of 0.3 and 4.5 mM Mg2+, respectively. The Ca2+-binding constant of S-1, which contained a 15,000 dalton component, was 8.6 x 10(5) M-1, and the maximum binding number was 0.7 mol per mol of S-1. The 15,000 dalton component could be exchanged with extraneous g2. S-1 which lacked the 15,000 component could not bind Ca2+ at free Ca2+ concentrations less than 0.1 mM. The Ca2+ binding to free g2 light chain was about 100 times weaker than the binding to myosin, as indicated previously for skeletal myosin (Okamoto, Y. & Yagi, K. (1976) J. Biochem. 80, 111--120). The Ca2+-binding constant was obtained as 4.1 x 10(3) M-1 in the absence of added Mg2+. Phosphorylation of g2 light chain did not affect the Ca2+ binding to the free g2 light chain or to myosin. Ca2+ binding to cardiac native tropomyosin was also measured.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
May
|
| pubmed:issn |
0021-924X
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
85
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
1245-55
|
| pubmed:dateRevised |
2009-11-19
|
| pubmed:meshHeading |
pubmed-meshheading:447615-Animals,
pubmed-meshheading:447615-Calcium,
pubmed-meshheading:447615-Kinetics,
pubmed-meshheading:447615-Macromolecular Substances,
pubmed-meshheading:447615-Myosins,
pubmed-meshheading:447615-Phosphorylation,
pubmed-meshheading:447615-Protein Binding,
pubmed-meshheading:447615-Swine
|
| pubmed:year |
1979
|
| pubmed:articleTitle |
Ca2+ bindings of pig cardiac myosin, subfragment-1, and g2 light chain.
|
| pubmed:publicationType |
Journal Article
|