Linked Life Data

7798183

Source:http://linkedlifedata.com/resource/pubmed/id/7798183

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1995-1-25
pubmed:abstractText
To elucidate the role of a flexible loop in the stability and function of Escherichia coli dihydrofolate reductase, glycine-121 in a flexible loop (residues 117-131), separated by 19 A from active site Asp27, was substituted by site-directed mutagenesis with eight amino acids (Ala, Val, Leu, Asp, Ser, Cys, Tyr, and His). The free energy change of unfolding decreased in the order of G121A > G121D > G121C > G121S, wild-type > G121H > G121Y > G121L > G121V. The thermal denaturation temperature decreased with all mutations, accompanied by a decrease in the calorimetric enthalpy of denaturation. The steady-state kinetic parameter for the enzyme reaction, Km, was only slightly influenced, but kcat was significantly decreased by the mutations, there being 3- (G121C) to 42-fold (G121L) decreases in kcat/Km compared to that of the wild-type enzyme. The effects of mutations on the stability and enzyme activity were statistically examined as a function of the hydrophobicity and volume of amino acids introduced. The diminished stability and activity with increases in the hydrophobicity and volume of amino acids suggest that the main effect of the mutations would be modification of the flexibility of the loop due to overcrowding of the bulky side chains, overcoming the enhancement of the hydrophobic interaction.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-924X
pubmed:author
pubmed:issnType
Print
pubmed:volume
116
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
34-41
pubmed:dateRevised
2007-12-19
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Point mutations at glycine-121 of Escherichia coli dihydrofolate reductase: important roles of a flexible loop in the stability and function.
pubmed:affiliation
Department of Applied Biological Science, Faculty of Agriculture, Nagoya University.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't