Linked Life Data

6308260

Source:http://linkedlifedata.com/resource/pubmed/id/6308260

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1983-9-23
pubmed:abstractText
The electrochemical properties of a widely accepted six-step reaction scheme for the Na+, K+-ATPase have been studied by computer simulation. Rate coefficients were chosen to fit the nonvectorial biochemical data for the isolated enzyme and a current-voltage (I-V) relation consistent with physiological observations was obtained with voltage dependence restricted to one (but not both) of the two translocational steps. The vectorial properties resulting from these choices were consistent with physiological activation of the electrogenic sodium pump by intracellular and extracellular sodium (Na+) and potassium (K+) ions. The model exhibited K+/K+ exchange but little Na+/Na+ exchange unless the energy available from the splitting of adenosine triphosphate (ATP) was reduced, mimicking the behavior seen in squid giant axon. The vectorial ionic activation curves were voltage dependent, resulting in large shifts in apparent Km's with depolarization. At potentials more negative than the equilibrium or reversal potential transport was greatly diminished unless the free energy of ATP splitting was reduced. While the pump reversal potential is at least 100 mV hyperpolarized relative to the resting potential of most cells, the voltage-dependent distribution of intermediate forms of the enzyme allows the possibility of considerable slope conductance of the pump I-V relation in the physiological range of membrane potentials. Some of the vectorial properties of an electrogenic sodium pump appear to be inescapable consequences of the nonvectorial properties of the isolated enzyme. Future application of this approach should allow rigorous quantitative testing of interpretative ideas concerning the mechanism and stoichiometry of the sodium pump.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0022-2631
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
139-53
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Electrical and biochemical properties of an enzyme model of the sodium pump.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't