Linked Life Data

12783549

Source:http://linkedlifedata.com/resource/pubmed/id/12783549

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
23
pubmed:dateCreated
2003-6-4
pubmed:abstractText
Reaction mechanisms for the formation of the keto-form of oxyluciferin (OxyLH(2)) from the luciferin of fireflies via a dioxetanone intermediate are predicted using the B3LYP/6-31G theoretical method. The ring opening of a model dioxetanone and the decarboxylation proceed in one step via a singlet diradical transition structure with an activation barrier of 18.1 and an exothermicity of 90.8 kcal/mol. The S(0) --> S(1) vertical excitation energies predicted with time dependent density functional theory, TDDFT B3LYP/6-31+G, for the anionic and neutral forms of OxyLH(2) are in the range of 60 to 80 kcal/mol. These energetic results support the generally accepted theory of chemically initiated electron exchange luminescence (CIEEL). The chemical origin of the multicolor bioluminescence from OxyLH(2) is examined theoretically using the TDDFT B3LYP/6-31+G, ZINDO//B3LYP/6-31+G, and CIS/6-31G methods. A change in color of the light emission upon rotation of the two rings in the S(1) excited state of OxyLH(2) is unlikely because both possible emitters, the planar keto- and enol-forms, are minima on the S(1) potential energy surface. The participation of the enol-forms of OxyLH(2) in bioluminescence is plausible but not required to explain the multicolor emission. According to predictions at the TDDFT B3LYP level, the color of the bioluminescence depends on the polarization of the OxyLH(2) in the microenvironment of the enzyme-OxyLH(2) complex.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0002-7863
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
125
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6962-71
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Theoretical study of the amazing firefly bioluminescence: the formation and structures of the light emitters.
pubmed:affiliation
Contribution from the Department of Chemistry and Biochemistry, Department of Food Science, University of Guelph, Guelph, Ontario, Canada, N1G 2W1.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't