Linked Life Data

7287706

Source:http://linkedlifedata.com/resource/pubmed/id/7287706

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
20
pubmed:dateCreated
1981-12-15
pubmed:abstractText
The enzyme kinetics of estrogen 2-hydroxylase from rat liver microsomes has been investigated using two radiotracer methods. The conversion of [4-14C]estradiol to [4-14C]2-hydroxyestradiol by microsomes was examined by isolation of the catechol estrogen. [6,7-3H]2-Hydroxyestradiol was prepared and added at the end of the incubation as a recovery marker for quantitation. Initial velocity conditions of less than 10% product formation were established. The enzyme kinetics for estrogen 2-hydroxylase from male rat liver follows classical Michaelis-Menten kinetics producing a linear Lineweaver-Burk plot. The apparent Km for estradiol under these conditions was 2.2 microM; the Vmax for freshly prepared microsomes was 5.0 nmol/mg/min while that for microsomes stored at -70 degrees C was 0.51 nmol/mg/min. On the other hand, estrogen 2-hydroxylase from female rat liver microsomes did not follow Michaelis-Menten kinetics and yielded a nonlinear double reciprocal plot. Analogous kinetic data were obtained with another radiotracer assay measuring the release of 3H2O from [2-3H]estradiol. Thus, the estrogen 2-hydroxylases of male and female rat liver differ in enzyme kinetic properties. The upwardly curving Lineweaver-Burk plot of the kinetic data of the female rat liver microsomes suggests that more than one binding site for estradiol may exist on this enzyme complex and/or that this particular estrogen 2-hydroxylase system exhibits cooperative effects.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
256
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10239-42
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1981
pubmed:articleTitle
Kinetics of rat liver microsomal estrogen 2-hydroxylase. Evidence for sex differences at initial velocity conditions.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't