Linked Life Data

15732988

Source:http://linkedlifedata.com/resource/pubmed/id/15732988

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2005-2-28
pubmed:abstractText
On the basis of the crystal structure of an aldehyde oxidoreductase, Huber et al. proposed a catalytic mechanism for the reductive half-reaction of xanthine oxidase which involves nucleophilic addition of Mo-bound hydroxide (Moco 1) to the substrate and hydride transfer from the substrate to sulfido group (Mo=S). Density functional theory calculations have been carried out for the oxidation of formaldehyde, acetaldehyde, formamide, and formamidine with Moco 2 to understand more detailed catalytic pathways. Our calculation results indicate that the anionic catalyst model acts as a nucleophile and is reactive for the oxidation of aldehyde substrates, which are reactive for nucleophilic addition. In these cases, a concerted mechanism is found to be more favorable than a stepwise mechanism. The concerted mechanism is further shown to be promoted by the presence of a nearby water molecule, in the active site, which serves as a Lewis acid for the nucleophilic addition of hydroxide. For less reactive formamide and formamidine (a model for xanthine) substrates, the calculated activation energies with the above mechanisms are high. These reactions also do not benefit from the presence of the water molecule. The results indicate that different catalyst forms might be responsible for the oxidation of different substrates, which could be regulated by the enzyme active site environment.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0020-1669
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
44
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1466-71
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
A theoretical study on the mechanism of the reductive half-reaction of xanthine oxidase.
pubmed:affiliation
Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't