Linked Life Data

9276671

Source:http://linkedlifedata.com/resource/pubmed/id/9276671

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1997-10-6
pubmed:abstractText
The mechanism of recognition of hydrophobic substrates was investigated using Escherichia coli aspartate aminotransferase (AspAT), E. coli aromatic amino acid aminotransferase (AroAT), and their chimeric enzyme (DY18). Surprisingly, broad substrate specificity was observed in the reaction of aminotransferases with hydrophobic substrates. The catalytic efficiency increased with an increase in the side chain length of straight or branched-terminal aliphatic substrates. The straight-chain substrates catalysed with maximal efficiency were the 7-carbon substrate in the case of AspAT and the 8-carbon substrate for AroAT and DY18. Consecutive addition of single methylene groups to the substrate had a constant effect on the stabilization energy of the transition state relative to the unbound state. The dependency of binding energy on each methylene group is usually interpreted as indicating hydrophobicity of the active site. However, we observed that AroAT and DY18 had different dependencies although both enzymes have the same residues in the substrate-binding pocket. For substrates with more than 7 carbons, the aminotransferases did not strictly distinguish between substrates with straight and branched side chains. These results suggest that the recognition of manifold hydrophobic substrates of different shapes might require not only the hydrophobicity of the active site but also enzyme flexibility.
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
122
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
55-63
pubmed:dateRevised
2007-12-19
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Enzyme flexibility: a new concept in recognition of hydrophobic substrates.
pubmed:affiliation
Department of Biology, Graduate School of Science, Osaka University.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't