Linked Life Data

9283097

Source:http://linkedlifedata.com/resource/pubmed/id/9283097

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
36
pubmed:dateCreated
1997-9-30
pubmed:abstractText
Glu139 of the large alpha-subunit of the multienzyme complex of fatty acid oxidation from Escherichia coli was identified as the catalytic residue of enoyl-CoA hydratase [Yang, S.-Y., He, X.-Y., & Schulz, H. (1995) Biochemistry 34, 6441-6447]. To determine whether any of the other conserved protic residues is directly involved in the hydratase catalysis, the multienzyme complexes with either an alpha/Asp69 --> Asn or an alpha/Glu119 --> Gln mutation were overproduced and characterized. The catalytic properties of 3-ketoacyl-CoA thiolase and l-3-hydroxyacyl-CoA dehydrogenase of the mutant complexes were almost unaffected. The amidation of Asp69 and Glu119 caused a 7.6- and 88-fold decrease, respectively, in the kcat of enoyl-CoA hydratase without a significant change in the Km value of the hydratase as well as a 5.9- and 62-fold increase, respectively, in the Km of Delta3-cis-Delta2-trans-enoyl-CoA isomerase with a very small decrease in the kcat of the latter enzyme. The data suggest that the carboxyl group of Glu119 is particularly important to the catalytic activity of enoyl-CoA hydratase. Furthermore, the wild-type hydratase shows a bell-shaped pH dependence of the kcat/Km with pKa values of 5.9 and 9.2, whereas the Glu119 --> Gln mutant hydratase has only a single pKa of 9.5. A simple explanation for these observations is that a deprotonated Glu119 and a protonated Glu139 are required for the high kcat of the enoyl-CoA hydratase. The results of site-directed mutagenesis studies, together with the structural information about the spatial arrangement of two conserved glutamate residues of rat liver enoyl-CoA hydratase [Engel, C. K., Mathieu, M., Zeelen, J. P., Hiltunen, J. K., and Wierenga, R. K. (1996) EMBO J. 15, 5135-5145] to which Glu119 and Glu139 of the large alpha-subunit correspond, lead to the conclusion that the gamma-carboxyl group of Glu119 serves as the second general acid-base functional group in catalyzing the hydration of 2-trans-enoyl-CoA.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
9
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11044-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Glutamate-119 of the large alpha-subunit is the catalytic base in the hydration of 2-trans-enoyl-coenzyme A catalyzed by the multienzyme complex of fatty acid oxidation from Escherichia coli.
pubmed:affiliation
Department of Pharmacology, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.