Linked Life Data

8515270

Source:http://linkedlifedata.com/resource/pubmed/id/8515270

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1993-7-22
pubmed:abstractText
The choline acetyltransferase (ChAT) reaction involves the transfer of the acetyl group of acetyl-CoA to choline, in which an active site histidine is believed to act as a general acid/base catalyst. A comparison of the deduced amino acid sequences of the enzyme from Drosophila, pig, rat, and Caernohabditis elegans revealed three conserved histidines: Drosophila His268, His393, and His426. Each of these histidines was replaced by a leucine and a glutamine, and the kinetic properties of each of the recombinant mutant enzymes were determined. The mutations yielded active His268Leu-ChAT, His268Gln-ChAT, and His393Gln-ChAT and inactive His393Leu-ChAT, His426Leu-ChAT, and His426Gln-ChAT. The kinetic constants Km(CoA), Km(acetylcholine), and Vmax were essentially the same for all of the active mutants. When the integrity of the CoASAc binding site was investigated in the inactive mutants, the data suggested that the binding site in His393Leu-ChAT is disrupted but conserved in His426Leu-ChAT and His426Gln-ChAT. These results suggest that His426 is an essential catalytic residue and could serve as an acid/base catalyst.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0022-3042
pubmed:author
pubmed:issnType
Print
pubmed:volume
61
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
247-53
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Functional analysis of conserved histidines in choline acetyltransferase by site-directed mutagenesis.
pubmed:affiliation
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.