Linked Life Data

2547448

Source:http://linkedlifedata.com/resource/pubmed/id/2547448

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1989-9-19
pubmed:abstractText
The oligomeric state of canine renal NA+/K+ -ATPase solubilized by octaethylene glycol n-dodecyl ether (C12E8) was studied by means of low-angle laser light scattering photometry coupled with high-performance gel chromatography (HPGC). At around 0 degree C the solubilized enzyme was separated into the (alpha beta)2-diprotomeric and alpha beta-protomeric protein components with Mr values of 302,000 +/- 10,000 and 156,000 +/- 4,000, respectively, in approximately equal quantities. As the temperature of chromatography was increased toward 20 degrees C, the two protein components converged into a single major component. The Mr of this component depended on the monovalent cation included in the elution buffer, and was 255,000 or 300,000 in the presence of 0.1 M NaCl or 0.1 M KCl, respectively. A computer simulation technique showed that the solubilized enzyme was in a dissociation-association equilibrium of 2 protomers = diprotomer at 20 degrees C, and the difference in apparent Mr of the solubilized enzyme between the two species of monovalent cation was interpreted by an association constant (Ka) in the presence of 0.1 M KCl that was about 50-fold larger than in the presence of 0.1 M NaCl. In order to measure ATPase activity and Mr of the solubilized enzyme simultaneously, a TSKgel G3000SW column had been equilibrated and was eluted with an elution buffer containing 0.30 mg/ml C12E8 and 60 microgram/ml phosphatidylserine (bovine brain) as well as the ligands necessary for the enzyme to exhibit the activity at pH 7.0 and 20 degrees C. The solubilized enzyme was always eluted as a single protein component irrespective of the the amount of the protein applied to the column, ranging between 240 and 10 microgram. The Mr of the protein component, however, decreased from 214,000 and 158,000 with the decrease of the protein amount. The specific ATPase activity, however, remained constant at a level of 64 +/- 4% of that of the membrane-bound enzyme even in the range of protein concentration sufficiently low as to allow the enzyme to exist only in the protomeric form. Thus, the alpha beta-protomer is concluded to be the minimum functional unit for the ATPase activity. The value of Ka obtained from the concentration-dependent dissociation curve was 5 . 10(5) M-1 for the enzyme turning over, and 1.1 . 10(7) M-1 for the enzyme inhibited with ouabain. It was discussed, based on the values of Ka obtained, that the enzyme would exist as the diprotomer or the higher oligomer in the membrane.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
983
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
217-29
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Minimum enzyme unit for Na+/K+-ATPase is the alpha beta-protomer. Determination by low-angle laser light scattering photometry coupled with high-performance gel chromatography for substantially simultaneous measurement of ATPase activity and molecular weight.
pubmed:affiliation
Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't