Linked Life Data

2642898

Source:http://linkedlifedata.com/resource/pubmed/id/2642898

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1989-2-17
pubmed:abstractText
Dihydrofolate reductase from Candida albicans was purified 31,000-fold and characterized. In addition, the C. albicans dihydrofolate reductase gene was cloned into a plasmid vector and expressed in Escherichia coli, and the enzyme was purified from this source. Both preparations showed a single protein-staining band with a molecular weight of about 25,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzymes were stable and had an isoelectric point of pH 7.1 on gel isoelectric focusing. Kinetic characterization showed that the enzymes from each source had similar turnover numbers (about 11,000 min-1) and Km values for NADPH and dihydrofolate of 3-4 microM. Like other eukaryotic dihydrofolate reductases, the C. albicans enzyme exhibited weak binding affinity for the antibacterial agent trimethoprim (Ki = 4 microM), but further characterization showed that the inhibitor binding profile of the yeast and mammalian enzymes differed. Methotrexate was a tight binding inhibitor of human but not C. albicans dihydrofolate reductase; the latter had a relatively high methotrexate Ki of 150 pM. The yeast and vertebrate enzymes also differed in their interactions with KCl and urea. These two agents activate vertebrate dihydrofolate reductases but inhibited the C. albicans enzyme. The sequence of the first 36 amino-terminal amino acids of the yeast enzyme was also determined. This portion of the C. albicans enzyme was more similar to human than to E. coli dihydrofolate reductases (50% and 30% identity, respectively). Some key amino acid residues in the C. albicans sequence, such as E-30 (human enzyme numbering), were "vertebrate-like" whereas others, such as I-31, were not. These results indicate that there are physical and kinetic differences between the eukaryotic mammalian and yeast enzymes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
264
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1100-7
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Characterization of Candida albicans dihydrofolate reductase.
pubmed:affiliation
Wellcome Research Laboratories, Research Triangle Park, North Carolina 27709.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.