Linked Life Data

9882455

Source:http://linkedlifedata.com/resource/pubmed/id/9882455

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1999-2-11
pubmed:abstractText
The rate-limiting step in the catalysis of the hydration of CO2 by carbonic anhydrase involves transfer of protons between zinc-bound water and solution. This proton transfer can be enhanced by proton shuttle residues within the active-site cavity of the enzyme. We have used chemical modulation to provide novel internal proton transfer groups that enhance catalysis by murine carbonic anhydrase V (mCA V). This approach involves the site-directed mutation of a targeted residue to a cysteine which is then subsequently reacted with an imidazole analog containing an appropriately positioned leaving group. Compounds examined include 4-bromoethylimidazole (4-BEI), 2-chloromethylimidazole (2-CMI), 4-chloromethylimidazole (4-CMI), and a triazole analog. Two sites in mCA V, Lys 91 and Tyr 131, located on the rim of the active-site cavity have been targeted for the introduction of these imidazole analogs. Modification of the introduced Cys 131 with 4-BEI and 4-CMI resulted in enhancements of up to threefold in catalytic activity. The pH profiles indicate the presence of a new proton shuttle residue of pKa near 5.8, consistent with the introduction of a functional proton transfer group into the active site. This is the first example of incorporation by chemical modification of an unnatural amino acid analog of histidine that can act as a proton shuttle in an enzyme.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0003-9861
pubmed:author
pubmed:copyrightInfo
Copyright 1999 Academic Press.
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
361
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
264-70
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Introduction of histidine analogs leads to enhanced proton transfer in carbonic anhydrase V.
pubmed:affiliation
Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida, 32610-0267, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't