Linked Life Data

3357339

Source:http://linkedlifedata.com/resource/pubmed/id/3357339

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1988-5-20
pubmed:abstractText
The activity of 4-ene-5 alpha-reductase was assayed in porcine testis homogenates and subcellular fractions, using testosterone as substrate. 'Marker' enzyme activities were utilized to indicate the purity of the subcellular fractions. 4-Ene-5 alpha-reductase activity was associated with the microsomal fraction; there was no activity in the purified nuclear fraction. Enzyme activity was higher in the testes of 6 week old pigs than those of 3 and 17 week old animals, and a range of activity was found. The enzyme was unstable when stored at -20 degrees C but the addition of albumin (0.1%, w/v) or glycerol (20%, v/v) to the buffer and storage at -70 degrees C or in liquid nitrogen ensured that maximal activity was retained for at least 35 days. In addition to 5 alpha-DHT, other 5 alpha-reduced metabolites and 4-androstenedione were formed in this reaction; NADPH was the preferred cofactor, but 40% of the 4-ene-5 alpha-reductase activity was retained when NADH was used. Solubilization of the microsomal enzyme was achieved using sodium citrate (0.1 M); 4-ene-5 alpha-reductase activity was enhanced to greater than 120% and 60% of this activity was in the soluble fraction. The optimum pH and temperature for both soluble and membrane-bound 4-ene-5 alpha-reductase were 6.9 and 32 degrees C, respectively. The mean apparent Km and Vmax were 0.6 mumol/l and 158 pmol/min/mg microsomal protein for the microsomal enzyme and 1.42 mumol/l and 212.0 pmol/min/mg soluble protein for the solubilized 4-ene-5 alpha-reductase. The estimated sedimentation coefficient was 11.6.
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
29
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
325-31
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Properties of 4-ene-5 alpha-reductase and studies on its solubilization from porcine testicular microsomes.
pubmed:affiliation
Division of Biochemistry, United Medical School (Guy's Hospital), London, England.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't