Switch to
Predicate | Object |
---|---|
rdf:type | |
lifeskim:mentions | |
pubmed:issue |
1
|
pubmed:dateCreated |
1986-5-12
|
pubmed:abstractText |
An enzyme preparation (IIIB) isolated from liver microsomes of untreated male rats was found to contain two activities--short-chain trans-2-enoyl-CoA hydratase and beta-ketoacyl-CoA reductase. The hydratase was purified more than 1000-fold, while the reductase activity was purified over 600-fold. Employing sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, a single band with a molecular weight of 76,000 was observed. Although attempts to separate these two activities have failed, it remains to be established whether the final preparation contains a single enzyme with two activities or two separate enzymes. The hydratase was most active toward crotonyl-CoA, followed by trans-2-hexenoyl-CoA (6:1) and -octenoyl-CoA (8:1); the enzyme was essentially inactive toward substrates containing more than eight carbon atoms. The Vmax for crotonyl-CoA was 2117 mumol/min/mg protein, while the Km was 59 microM. Using acetoacetyl-CoA as substrate, the Vmax for the beta-ketoacyl-CoA reductase was over 60 mumol/min/mg protein and the Km was 37 microM; the Vmax for beta-ketopalmitoyl-CoA was only 15% of that observed with acetoacetyl-CoA, although the Km was 6 microM. During the course of purification, a second short-chain hydratase was discovered (fraction IVA); unlike IIIB, this fraction catalyzed the hydration of 4:1, 6:1, and 8:1 at similar rates. The partially purified preparation yielded maximal activity with 8:1 CoA (apparent Vmax 35 mumol/min/mg), followed by 6:1 CoA, 4:1 CoA, and 10:1 CoA; longer chain CoA's were relatively poor substrates, with trans-2-hexadecenoyl CoA about 0.1 as active as 8:1 CoA. On SDS-gels, fraction IVA contained four bands, all of which were below 60,000 Mr. Proteases, such as trypsin, chymotrypsin, and subtilisin, were found to completely inactivate both enzyme fractions.
|
pubmed:grant | |
pubmed:language |
eng
|
pubmed:journal | |
pubmed:citationSubset |
IM
|
pubmed:chemical | |
pubmed:status |
MEDLINE
|
pubmed:month |
Apr
|
pubmed:issn |
0003-9861
|
pubmed:author | |
pubmed:issnType |
Print
|
pubmed:volume |
246
|
pubmed:owner |
NLM
|
pubmed:authorsComplete |
Y
|
pubmed:pagination |
206-16
|
pubmed:dateRevised |
2007-11-14
|
pubmed:meshHeading |
pubmed-meshheading:3516072-Alcohol Oxidoreductases,
pubmed-meshheading:3516072-Animals,
pubmed-meshheading:3516072-Chromatography, Affinity,
pubmed-meshheading:3516072-Electrophoresis, Polyacrylamide Gel,
pubmed-meshheading:3516072-Kinetics,
pubmed-meshheading:3516072-Microsomes, Liver,
pubmed-meshheading:3516072-Potassium Chloride,
pubmed-meshheading:3516072-Rats,
pubmed-meshheading:3516072-Solubility,
pubmed-meshheading:3516072-Substrate Specificity
|
pubmed:year |
1986
|
pubmed:articleTitle |
Isolation of rat liver microsomal short-chain beta-ketoacyl-coenzyme A reductase and trans-2-enoyl-coenzyme A hydratase: evidence for more than one hydratase.
|
pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
|