Linked Life Data

2040304

Source:http://linkedlifedata.com/resource/pubmed/id/2040304

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1991-7-10
pubmed:abstractText
The protozoan haemoflagellate Trypanosoma brucei has two NAD-dependent glyceraldehyde-3-phosphate dehydrogenase isoenzymes, each with a different localization within the cell. One isoenzyme is found in the cytosol, as in other eukaryotes, while the other is found in the glycosome, a microbody-like organelle that fulfils an essential role in glycolysis. The kinetic properties of the purified glycosomal and cytosolic isoenzymes were compared with homologous enzymes from other organisms. Both trypanosome enzymes had pH/activity profiles similar to that of other glyceraldehyde-3-phosphate dehydrogenases, with optimal activity around pH 8.5-9. Only the yeast enzyme showed its maximal activity at a lower pH. The glycosomal enzyme was more sensitive to changes in ionic strength below 0.1 M, while the cytosolic enzyme resembled more the enzymes from rabbit muscle, human erythrocytes and yeast. The affinity for NAD of the glycosomal enzyme was 5-10-fold lower than that of the cytosolic, as well as the other enzymes. A similar, but less pronounced, difference was found for its affinity for NADH. These differences are explained by a number of amino acid substitutions in the NAD-binding domain of the glycosomal isoenzyme. In addition, the effects of suramin, gossypol, agaricic acid and pentalenolactone on the trypanosome enzymes were studied. The trypanocidal drug suramin inhibited both enzymes, but in a different manner. Inhibition of the cytosolic enzyme was competitive with NAD, while in the case of the glycosomal isoenzyme, with NAD as substrate, the drug had an effect both on Km and Vmax. The most potent inhibitor was pentalenolactone, which at micromolar concentrations inhibited the glycosomal enzyme and the enzymes from yeast and Bacillus stearothermophilus in a reversible manner, while the rabbit muscle enzyme was irreversibly inhibited.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
198
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
429-35
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
The cytosolic and glycosomal glyceraldehyde-3-phosphate dehydrogenase from Trypanosoma brucei. Kinetic properties and comparison with homologous enzymes.
pubmed:affiliation
International Institute of Cellular and Molecular Pathology, Research Unit for Tropical Diseases, Brussels, Belgium.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't