Linked Life Data

20937239

Source:http://linkedlifedata.com/resource/pubmed/id/20937239

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2011-1-10
pubmed:abstractText
The pyridoxal 5'-phosphate (PLP)-dependent enzyme O-acetylserine sulfhydrylase (OASS) catalyzes the synthesis of cysteine in bacteria and plants. In bacteria two isoenzymes are present, OASS-A and OASS-B, with distinct structural, functional, and regulatory properties. In order to gain a deeper insight into OASS-B dynamic and functional properties, single and double mutants of the three tryptophan residues, Trp28, Trp159, and Trp212, were prepared and their fluorescence emission properties were characterized in the absence and presence of substrate and ligands by steady-state and time-resolved spectrofluorimetry. Residue Trp28 was found to be mainly responsible for Trp fluorescence emission, whereas Trp212, located in a highly flexible region near the active site, is mainly responsible for an energy-transfer to PLP leading to an emission at 500 nm. Not surprisingly, mutation of Trp212 affects OASS-B activity. Trp159 slightly contributes to both direct emission and energy transfer to PLP. Time-resolved fluorescence measurements confirmed these findings, observing a third longer tryptophan lifetime for apo-OASS-B, in addition to the two lifetimes that are present in the holo-enzyme and mutants. A comparison with the emissions previously determined for OASS-A indicates that OASS-B active site is likely to be more polar and flexible, in agreement with a broader substrate specificity and higher catalytic efficiency.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1096-0384
pubmed:author
pubmed:copyrightInfo
Copyright © 2010 Elsevier Inc. All rights reserved.
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
505
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
178-85
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Exploring O-acetylserine sulfhydrylase-B isoenzyme from Salmonella typhimurium by fluorescence spectroscopy.
pubmed:affiliation
Department of Biochemistry and Molecular Biology, University of Parma, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't