Linked Life Data

2187529

Source:http://linkedlifedata.com/resource/pubmed/id/2187529

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
15
pubmed:dateCreated
1990-6-26
pubmed:abstractText
Escherichia coli thioredoxin is a small disulfide-containing redox protein with the active site sequence Cys-Gly-Pro-Cys-Lys. Mutations were made in this region of the thioredoxin gene and the mutant proteins expressed in E. coli strains lacking thioredoxin. Mutant proteins with a 17-membered or 11-membered disulfide ring were inactive in vivo. However, purified thioredoxin with the active site sequence Cys-Gly-Arg-Pro-Cys-Lys is still able to serve as a substrate for thioredoxin reductase and a reducing agent in the ribonucleotide reductase reaction, although with greatly reduced catalytic efficiency. A smaller disulfide ring, with the active site sequence Cys-Ala-Cys, does not turn over at a sufficient rate to be an effective reducing agent. Strain in the small ring favors the formation of intermolecular disulfide bonds. Alteration of the invariant proline to a serine has little effect on redox activity. The function of this residue may be in maintaining the stability of the active site region rather than participation in redox activity or protein-protein interactions. Mutation of the positively charged lysine in the active site to a glutamate residue raises the Km values with interacting enzymes. Although it has been proposed that the positive residue at position 36 is conserved to maintain the thiolate anion on Cys-32 (Kallis & Holmgren, 1985), the presence of the negative charge at this position does not alter the pH dependence of activity or fluorescence behavior. The lysine is most likely conserved to facilitate thioredoxin-protein interactions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
17
pubmed:volume
29
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3701-9
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Characterization of Escherichia coli thioredoxins with altered active site residues.
pubmed:affiliation
Department of Plant Biology, University of Minnesota, St. Paul 55108.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't