Linked Life Data

3502362

Source:http://linkedlifedata.com/resource/pubmed/id/3502362

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1988-5-31
pubmed:abstractText
Uniquely among class A beta-lactamases, the RTEM-1 and RTEM-2 enzymes contain a single disulfide bond between Cys 77 and Cys 123. To study the possible role of this naturally occurring disulfide in stabilizing RTEM-1 beta-lactamase and its mutants at residue 71, this bond was removed by introducing a Cys 77----Ser mutation. Both the wild-type enzyme and the single mutant Cys 77----Ser confer the same high levels of resistance to ampicillin in vivo to Escherichia coli; at 30 degrees C the specific activity of purified Cys 77----Ser mutant is also the same as that of the wild-type enzyme. Also, neither wild-type enzyme nor the Cys 77----Ser mutant is inactivated by brief exposure to p-hydroxymercuribenzoate. However, above 40 degrees C the mutant enzyme is less stable than wild-type enzyme. After introduction of the Cys 77----Ser mutation, none of the double mutants (containing the second mutations at residue 71) confer resistance to ampicillin in vivo at 37 degrees C; proteins with Ala, Val, Leu, Ile, Met, Pro, His, Cys, and Ser at residue 71 confer low levels of resistance to ampicillin in vivo at 30 degrees C. The use of electrophoretic blots stained with antibodies against beta-lactamase to analyze the relative quantities of mutant proteins in whole-cell extracts of E. coli suggests that all 19 of the doubly mutant enzymes are proteolyzed much more readily than their singly mutant analogues (at Thr 71) that contain a disulfide bond.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0887-3585
pubmed:author
pubmed:issnType
Print
pubmed:volume
2
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
290-7
pubmed:dateRevised
2008-8-22
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Stability of wild-type and mutant RTEM-1 beta-lactamases: effect of the disulfide bond.
pubmed:affiliation
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125.
pubmed:publicationType
Journal Article