Linked Life Data

152646

Source:http://linkedlifedata.com/resource/pubmed/id/152646

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1979-2-23
pubmed:abstractText
The soluble Ca2+-ATPase from Escherichia coli had a distinctive behavior with respect to inhibition by Na+ measured at 36 degrees C and 19 degrees C. At the first temperature the Hill plots are linear and show a slope of 1.1 while at 19 degrees C the plots are biphasic, with slopes of 1.8 and 0.8 before and after the break, respectively. The break occurs at about 50 nM NaCl. Gel chromatography was performed in jacketed Sepharose 4B columns kept at 2 temperatures in the presence of different concentrations of NaCl. It was found that the Stokes' radius of the enzyme was dependent on the temperature and on the salt concentration. Equilibrium sucrose gradients run at 19 degrees C showed that the sedimentation constant of the enzyme remained constant irrespective of the NaCl concentration used. It is concluded that a "folding" of the enzyme takes place in the presence of NaCl, the process being complete at about 50 mM NaCl at 19 degrees C and at about 20 mM at 36 degrees C. The results are in excellent agreement with the kinetic data: the "folded" or "compact" configuration would show no cooperative response towards Na+ while the "expanded" conformer would present strong cooperativity. This is also in agreement with the results obtained with the enzyme embedded in the membrane: when the membrane is fluid a high n value (Hill coefficient) is found; when the membrane is more rigid the value of n falls. A model explaining all our results is proposed and discussed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
513
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
78-88
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1978
pubmed:articleTitle
Membrane-bound cooperative enzymes. Stokes' radii, Hill plots and membrane fluidity in the regulation of adenosinetriphosphatase from Escherichia coli.
pubmed:publicationType
Journal Article