Linked Life Data

2438480

Source:http://linkedlifedata.com/resource/pubmed/id/2438480

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1987-7-2
pubmed:abstractText
The nuclear conversion of testosterone (T) to dihydrotestosterone (DHT) was compared in the separated stromal and epithelial fractions of hyperplastic (n = 20), malignant (n = 5) and normal (n = 1) prostatic tissues. Standard assay conditions were: 1 microM testosterone, plus 4-6 X 10(5) DPM [3H]T, 1.0 mM NADPH, 2.0 mM EDTA and 0.5-1.0 mg nuclear protein in a total volume of 1.1 ml HEPES buffer, pH 7.4 (stroma) or MES buffer, pH 6.5 (epithelium). The apparent Km values for the stromal enzyme were 0.2, 0.2 and 0.3 microM, respectively, for the enzymes in hyperplastic, malignant and normal tissues. The Vmax values were 26 +/- 4.2, 2.8 +/- 0.6 and 4.1 pmol/mg protein/30 min incubation, respectively, for these same tissues. The apparent Km values for the epithelial enzymes, from the same tissues, were 0.03, 0.07 and 0.08 microM. The Vmax values for the epithelial enzymes were 4.8 +/- 1.2, 0.69 +/- 0.08 and 1.1 pmol/mg protein/30 min incubation. The pH optimum for the stromal enzyme lay between pH 6.5 and 7.5, whereas the pH optimum for the epithelial enzyme lay between 5.5 and 6.5. Enzymatic activity in both fractions revealed a biphasic response to zinc. In the absence of EDTA, microM quantities of zinc enhanced enzymatic activity while mM quantities inhibited this activity. These results would suggest that differences in the conversion of T to DHT help to explain, at least in part, the higher DHT levels seen in hyperplastic tissue and the higher T levels seen in the malignant prostate.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0022-4731
pubmed:author
pubmed:issnType
Print
pubmed:volume
26
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
349-53
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Comparison of nuclear 5 alpha-reductase activities in the stromal and epithelial fractions of human prostatic tissue.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't