Linked Life Data

1400267

Source:http://linkedlifedata.com/resource/pubmed/id/1400267

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1992-11-10
pubmed:abstractText
We have constructed an efficient expression plasmid for the leucine dehydrogenase gene previously cloned from Bacillus stearothermophilus. The recombinant enzyme was overproduced in Escherichia coli cells to a level of more than 30% of the total soluble protein upon induction with isopropyl beta-D-thiogalactopyranoside. The enzyme could be readily purified to homogeneity by heat treatment and a single step of ion-exchange chromatography. The purified enzyme was inactivated in a time-dependent manner upon incubation with pyridoxal 5'-phosphate (PLP) followed by reduction with sodium borohydride. The inactivation was completely prevented in the copresence of L-leucine and NAD+. Concomitantly with the inactivation, several molecules of PLP were incorporated into each subunit of the hexameric enzyme. Sequence analysis of the fluorescent peptides isolated from a proteolytic digest of the modified protein revealed that Lys80, Lys91, Lys206, and Lys265 were labeled. Among these residues, Lys80 was predominantly labeled and, in the presence of L-leucine and NAD+, was specifically protected from the labeling. Furthermore, a linear relationship of about 1:1 was observed between the extent of inactivation and the amount of PLP incorporated into Lys80. A slightly active mutant enzyme, in which Lys80 is replaced by Ala, was not inactivated at all by incubation with PLP, showing that the inactivation is correlated with the labeling of only Lys80. Lys80is conserved in the corresponding regions of all the amino acid dehydrogenase sequences reported to date. These results suggest that Lys80 is located at the active site and plays an important role in the catalytic function of leucine dehydrogenase.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-924X
pubmed:author
pubmed:issnType
Print
pubmed:volume
112
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
258-65
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Leucine dehydrogenase from Bacillus stearothermophilus: identification of active-site lysine by modification with pyridoxal phosphate.
pubmed:affiliation
Institute of Scientific and Industrial Research, Osaka University.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't