Linked Life Data

2598930

Source:http://linkedlifedata.com/resource/pubmed/id/2598930

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
1990-1-31
pubmed:abstractText
The rate of pregnenolone synthesis by cytochrome P-450scc was measured in mitochondria isolated from ovaries of immature rats treated with pregnant mare's serum gonadotropin and human choriogonadotropin. Using cholesterol, 25-hydroxycholesterol, 20 alpha-hydroxycholesterol, (22R)-22-hydroxycholesterol and (22R)-20 alpha,22-dihydroxycholesterol as substrates, we have determined that the first hydroxylation of cholesterol, in the 22R position, is rate limiting in pregnenolone synthesis. It proceeds at only 22% of the rate of either of the subsequent two hydroxylations. 25-Hydroxycholesterol proved to be a suitable substrate for determining the maximum rate of pregnenolone synthesis by cytochrome P-450scc in isolated mitochondria. The maximum rate was 13 mol steroid.min-1.mol cytochrome P-450scc-1 and did not change after the follicles in the immature ovary had been stimulated to mature and luteinize with gonadotropin. Using endogenous cholesterol in isolated mitochondria as substrate, the time course of pregnenolone synthesis was the same during the follicular phase as in the luteal stage of gonadotropin-induced development. We conclude that during the artificial induced development of follicles in the immature ovary, the major cause of the increase in the rate of pregnenolone synthesis is the increase in the cytochrome P-450scc content of the mitochondria, rather than changes in the catalytic activity of cytochrome P-450scc or the cholesterol availability to the cytochrome.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
186
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
255-9
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Pregnenolone synthesis from cholesterol and hydroxycholesterols by mitochondria from ovaries following the stimulation of immature rats with pregnant mare's serum gonadotropin and human choriogonadotropin.
pubmed:affiliation
Department of Biochemistry, University of Western Australia, Perth.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't