Linked Life Data

16928124

Source:http://linkedlifedata.com/resource/pubmed/id/16928124

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
34
pubmed:dateCreated
2006-8-24
pubmed:abstractText
High-level quantum chemistry calculations have been carried out to investigate beta-scission reactions of alkoxyl radicals located at the alpha-carbon of a peptide backbone. This type of alkoxyl radical may undergo three possible beta-scission reactions, namely C-C beta-scission of the backbone, C-N beta-scission of the backbone, and C-R beta-scission of the side chain. We find that the rates for the C-C beta-scission reactions are all very fast, with rate constants of the order 10(12) s(-1) that are essentially independent of the side chain. The C-N beta-scission reactions are all slow, with rate constants that range from 10(-0.7) to 10(-4.5) s(-1). The rates of the C-R beta-scission reactions depend on the side chain and range from moderately fast (10(7) s(-1)) to very fast (10(12) s(-1)). The rates of the C-R beta-scission reactions correlate well with the relative stabilities of the resultant side-chain product radicals (*R), as reflected in calculated radical stabilization energies (RSEs). The order of stabilities for the side-chain fragment radicals for the natural amino acids is found to be Ala < Glu < Gln approximately Leu approximately Met approximately Lys approximately Arg < Asp approximately Ile approximately Asn approximately Val < Ser approximately Thr approximately Cys < Phe approximately Tyr approximately His approximately Trp. We predict that for side-chain C-R beta-scission reactions to effectively compete with the backbone C-C beta-scission reactions, the side-chain fragment radicals would generally need an RSE greater than approximately 30 kJ mol(-1). Thus, the residues that may lead to competitive side-chain beta-scission reactions are Ser, Thr, Cys, Phe, Tyr, His, and Trp.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
1089-5639
pubmed:author
pubmed:issnType
Print
pubmed:day
31
pubmed:volume
110
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10316-23
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Effect of side chains on competing pathways for beta-scission reactions of peptide-backbone alkoxyl radicals.
pubmed:affiliation
School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't