Linked Life Data

698209

Source:http://linkedlifedata.com/resource/pubmed/id/698209

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1978-12-27
pubmed:abstractText
The effect of variation in the microsomal membrane fatty acid composition on Arrhenius plot phase transition temperatures for p-nitroanisole O-demethylation and benzo[a]pyrene hydroxylation has been investigated. In liver microsomes from normal-dieted rats, p-nitroanisole O-demethylase activity has a break temperature at 24 degrees C, while that of benzo[a]pyrene hydroxylase occurs at 29 degrees C indicating that these two enzymes may exist in different patches of membrane. The microsomal membrane fatty acid composition was altered by starving rats for 48 h and then refeeding them a fat-free diet for 4 or 5 days. In microsomes having diet-altered fatty acid compositions, benzo[a]pyrene hydroxylase has a break temperature at 33 degrees C, a value higher than that observed in normal-dieted rats. This observation correlates with the increase in saturation observed in the diet-altered fatty acid composition and thus may correspond to a phase transition roughly dependent on the fatty acid melting point. Induced and basal levels of cytochrome P-450 and P-448 in animals having different microsomal fatty acid composition are reported. Phenobarbital-induced levels of p-nitroanisole O-demethylase in normal microsomes were six times higher than those in microsomes having diet-altered composition, whereas 3-methylcholanthrene-induced levels of benzo[a]pyrene hydroxylase were similar regardless of diet. The low level of p-nitroanisole O-demethylase activity in membranes with altered fatty acid compositions suggests that a particular type(s) of fatty acid was not present in sufficient quantity to permit the induction of maximal enzyme activity. Since the induced benzo[a]pyrene hydroxylase activity was the same regardless of diet, there was presumably sufficient quantities of the appropriate fatty acids present in the membrane for induction of this activity. Therefore, particular fatty acids may be necessary for the induction of maximal activity of particular enzymes in the mixed function monooxygenase system.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
512
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
136-46
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1978
pubmed:articleTitle
Fatty acid requirements and temperature dependence of monooxygenase activity in rat liver microsomes.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.