Linked Life Data

115596

Source:http://linkedlifedata.com/resource/pubmed/id/115596

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2-3
pubmed:dateCreated
1980-1-19
pubmed:abstractText
Rat-liver microsomes were treated with two non-ionic detergents, Triton X-100 and Lubrol WX, with phospholipase A2, or with aqueous acetone solution. The activity of the membrane-bound UDP-glucoronosyltransferase (UDPGT, EC 2.4.1.17) was measured after the treatment with these perturbants. At the same time, modifications of the secondary structure of the microsomal proteins were followed and studied by circular dichroism (CD) spectroscopy. The detergents greatly activated UDPGT, maximally at a 1 mM concentration of either detergent. The maximally activating Triton X-100 treatment did not greatly change the ellipticity of the microsomes at 222 nm ((theta)222), whereas that with Lubrol WX affected the secondary structure of the membrane proteins more strongly. UDPGT activation also occurred in phospholipase A2-treated microsomes. Maximal activation was obtained after 1--5 min of incubation and was stable throughout the experiment. Phospholipase A2 at the ratio of microsomal protein to phospholipase 250 : 1 (w/w) slightly increased (theta)222 after 10 min of incubation and did not change it further even after 30 min of incubation. Treatment of liver microsomes with a 10 : 90 (v/v) aqueous acetone solution removed 90% of the total membrane phospholipids, particularly phosphatidylcholine and phosphatidylethanolamine. The UDPGT activity was decreased in lipid-depleted microsomes, and the enzyme was not reactivated when phosphatidylcholine-lysophosphatidylcholine liposomes were added at a low temperature. An even greater decrease was obtained when the lipid binding was carried out at 37 degree C. Lipid-depleted microsomes had a high (theta)222 associated with a red-shift of 2 nm, indicating partial aggregation of membrane proteins and an increase in the alpha-helical content of the protein after acetone extraction. However, this particular protein structure was partially reversible, since a binding of phospholipids to lipid-depleted microsomes gave a (theta)222 close to that found in control microsomes. The UDPGT activity was not dependent on the secondary structure of the membrane proteins.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0009-2797
pubmed:author
pubmed:issnType
Print
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
255-68
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1979
pubmed:articleTitle
Effects of membrane perturbants on UDP-glucuronosyltransferase activity in rat-liver microsomes. Circular dichroism studies.
pubmed:publicationType
Journal Article