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Hydration structure and conformational dynamics of urocanic acid: a computer simulation study
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
2002 Ingår i: Molecular Physics, ISSN 0026-8976, Vol. 100, nr 12, s. 1873-Artikel i tidskrift (Refereegranskat) Published
Ort, förlag, år, upplaga, sidor
2002. Vol. 100, nr 12, s. 1873-
Identifikatorer
URN: urn:nbn:se:su:diva-23381OAI: oai:DiVA.org:su-23381DiVA, id: diva2:191664
Anmärkning
Part of urn:nbn:se:su:diva-261Tillgänglig från: 2004-10-07 Skapad: 2004-10-07Bibliografiskt granskad
Ingår i avhandling
1. Computational chemistry studies of UV induced processes in human skin
Öppna denna publikation i ny flik eller fönster >>Computational chemistry studies of UV induced processes in human skin
2004 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

This thesis presents and uses the techniques of computational chemistry to explore two different processes induced in human skin by ultraviolet light. The first is the transformation of urocanic acid into a immunosuppressing agent, and the other is the enzymatic action of the 8-oxoguanine glycosylase enzyme.

The photochemistry of urocanic acid is investigated by time-dependent density functional theory. Vertical absorption spectra of the molecule in different forms and environments is assigned and candidate states for the photochemistry at different wavelengths are identified.

Molecular dynamics simulations of urocanic acid in gas phase and aqueous solution reveals considerable flexibility under experimental conditions, particularly for for the cis isomer where competition between intra- and inter-molecular interactions increases flexibility.

A model to explain the observed gas phase photochemistry of urocanic acid is developed and it is shown that a reinterpretation in terms of a mixture between isomers significantly enhances the agreement between theory and experiment , and resolves several peculiarities in the spectrum.

A model for the photochemistry in the aqueous phase of urocanic acid is then developed, in which two excited states governs the efficiency of photoisomerization. The point of entrance into a conical intersection seam is shown to explain the wavelength dependence of photoisomerization quantum yield.

Finally some mechanistic aspects of the DNA repair enzyme 8-oxoguanine glycosylase is investigated with density functional theory. It is found that the critical amino acid of the active site can provide catalytic power in several different manners, and that a recent proposal involving a SN1 type of mechanism seems the most efficient one.

Ort, förlag, år, upplaga, sidor
Stockholm: Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, 2004. s. 260
Nyckelord
Photochemistry, Theoretical chemistry, Density functional theory, UV effects, TD-DFT, enzyme catalysis, DNA damage, Molecular dynamics
Nationell ämneskategori
Fysikalisk kemi
Identifikatorer
urn:nbn:se:su:diva-261 (URN)91-7265-960-2 (ISBN)
Disputation
2004-10-29, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 13:00
Opponent
Handledare
Tillgänglig från: 2004-10-07 Skapad: 2004-10-07Bibliografiskt granskad

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