Source:http://linkedlifedata.com/resource/pubmed/id/14608618
Switch to
| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
22
|
| pubmed:dateCreated |
2003-11-10
|
| pubmed:abstractText |
Loss of H2S is the characteristic Cys side-chain fragmentation of the [M-H]- anions of Cys-containing peptides. A combination of experiment and theory suggests that this reaction is initiated from the Cys enolate anion as follows: RNH-(-)C(CH2SH)CONHR' Ø [RNHC(=CH2)CONHR' (HS-)] Ø [RNHC(=CH2)CO-HNR'-H]-+H2S. This process is facile. Calculations at the HF/6-31G(d)//AM1 level of theory indicate that the initial anion needs only > or =20.1 kcal mol(-1) of excess energy to effect loss of H2S. Loss of CH2S is a minor process, RNHCH(CH2SH)CON(-)-R' Ø RNHCH(CH2S-)CONHR' Ø RNH -CHCONHR+CH2S, requiring an excess energy of > or =50.2 kcal mol(-1). When Cys occupies the C-terminal end of a peptide, the major fragmentation from the [M-H]- species involves loss of (H2S+CO2). A deuterium-labelling study suggests that this could either be a charge-remote reaction (a process which occurs remote from and uninfluenced by the charged centre in the molecule), or an anionic reaction initiated from the C-terminal CO2- group. These processes have barriers requiring the starting material to have an excess energy of > or =79.6 (charge-remote) or > or =67.1 (anion-directed) kcal mol(-1), respectively, at the HF/6-31G(d)//AM1 level of theory. The corresponding losses of CH2O and H2O from the [M-H]- anions of Ser-containing peptides require > or =35.6 and > or =44.4 kcal mol(-1) of excess energy (calculated at the AM1 level of theory), explaining why loss of CH2O is the characteristic side-chain loss of Ser in the negative ion mode.
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:issn |
0951-4198
|
| pubmed:author | |
| pubmed:copyrightInfo |
Copyright 2003 John Wiley & Sons, Ltd.
|
| pubmed:issnType |
Print
|
| pubmed:volume |
17
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
2488-94
|
| pubmed:dateRevised |
2006-11-15
|
| pubmed:meshHeading | |
| pubmed:year |
2003
|
| pubmed:articleTitle |
The fragmentations of [M-H]- anions derived from underivatised peptides. The side-chain loss of H2S from Cys. A joint experimental and theoretical study.
|
| pubmed:affiliation |
Department of Chemistry, The University of Adelaide, South Australia, 5005 Australia.
|
| pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
|