Linked Life Data

10816001

Source:http://linkedlifedata.com/resource/pubmed/id/10816001

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3-4
pubmed:dateCreated
2000-6-15
pubmed:abstractText
Different substituents (NO2, C6H5, NH2, NH-CH=CH-CHO) to a methylene group were taken into account to investigate under which conditions the mechanism of formation of carbanions by proton transfer to a base (methylamine) can be favorable, as a preliminary study of the reaction catalyzed by semicarbazide-sensitive amine oxidases. Three different approaching paths of methylamine to C(alpha) in NO2-C(alpha)H2-NO2, and the relevant potential energy surfaces, were examined at the SCF/3-21G and 6-31G* levels. The proton transfer along the first two paths occurred with a similar barrier, which became fairly consistent after including the MP2 correlation correction, with either basis set, while the last approaching path was abandoned. For the other model systems the minimum was searched only at the 3-21G level in the vicinity of the first reaction path. The substitution of a nitro group with a phenyl group sharply raised the barrier for the proton transfer to methylamine. Also by substituting the second nitro group with either -NH2 or -NH-CH=CH-CHO, a steep uphill pathway was found. A more realistic model of the substrate-cofactor complex, namely the Schiff base between benzylamine and pyridoxal, again produced a barrier, almost matching that obtained for C6H5-C(alpha)H2-NO2. In both cases, the energy profiles for the rotation about the CC(alpha)NC dihedral and the proton shift tautomers were also considered at the 3-21G and 6-31G* levels. A preliminary scan of the effect of methyl (or methylphosphate) substitutions to the pyridoxal ring was performed and the stability of the Schiff bases involving other cofactors was also considered.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0097-8485
pubmed:author
pubmed:issnType
Print
pubmed:volume
24
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
311-24
pubmed:dateRevised
2000-12-18
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
A theoretical study on reaction pathways to carbanions.
pubmed:affiliation
CNR, Istituto di Chimica Quantistica ed Energetica Molecolare, Pisa, Italy.
pubmed:publicationType
Journal Article