Linked Life Data

18346723

Source:http://linkedlifedata.com/resource/pubmed/id/18346723

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
2008-6-23
pubmed:abstractText
Sucrose phosphorylase utilizes a glycoside hydrolase-like double displacement mechanism to convert its disaccharide substrate and phosphate into alpha-d-glucose 1-phosphate and fructose. Site-directed mutagenesis was employed to characterize the proposed roles of Asp(196) and Glu(237) as catalytic nucleophile and acid-base, respectively, in the reaction of sucrose phosphorylase from Leuconostoc mesenteroides. The side chain of Asp(295) is suggested to facilitate the catalytic steps of glucosylation and deglucosylation of Asp(196) through a strong hydrogen bond (23 kJ/mol) with the 2-hydroxyl of the glucosyl oxocarbenium ion-like species believed to be formed in the transition states flanking the beta-glucosyl enzyme intermediate. An assortment of biochemical techniques used to examine the mechanism of alpha-retaining glucosyl transfer by Schizophyllum commune alpha,alpha-trehalose phosphorylase failed to provide evidence in support of a similar two-step catalytic reaction via a covalent intermediate. Mutagenesis studies suggested a putative active-site structure for this trehalose phosphorylase that is typical of retaining glycosyltransferases of fold family GT-B and markedly different from that of sucrose phosphorylase. While ambiguity remains regarding the chemical mechanism by which the trehalose phosphorylase functions, the two disaccharide phosphorylases have evolved strikingly different reaction coordinates to achieve catalytic efficiency and stereochemical control in their highly analogous substrate transformations.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0008-6215
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
343
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2032-40
pubmed:dateRevised
2011-4-6
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Mechanistic differences among retaining disaccharide phosphorylases: insights from kinetic analysis of active site mutants of sucrose phosphorylase and alpha,alpha-trehalose phosphorylase.
pubmed:affiliation
Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria.
pubmed:publicationType
Journal Article, Review, Research Support, Non-U.S. Gov't