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A Quantum Chemical Study of the Synthesis of Prostaglandin G2 by the Cyclooxygenase Active Site in Prostaglandin Endoperoxide H Synthase 1
Stockholm University, Faculty of Science, Department of Physics.
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2003 In: Journal of Physical Chemistry B, ISSN 1520-6106, Vol. 107, 3297-3308 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2003. Vol. 107, 3297-3308 p.
URN: urn:nbn:se:su:diva-25809OAI: diva2:200557
Part of urn:nbn:se:su:diva-863Available from: 2006-02-20 Created: 2006-02-20Bibliographically approved
In thesis
1. Redox Reactions of NO and O2 in Iron Enzymes: A Density Functional Theory Study
Open this publication in new window or tab >>Redox Reactions of NO and O2 in Iron Enzymes: A Density Functional Theory Study
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the present thesis the density functional B3LYP has been used to study reactions of NO and O2 in redox active enzymes.

Reduction of nitric oxide (NO) to nitrous oxide (N2O) is an important part in the bacterial energy conservation (denitrification). The reduction of NO in three different bimetallic active sites leads to the formation of hyponitrous acid anhydride (N2O22-). The stability of this intermediate is crucial for the reaction rate. In the two diiron systems, respiratory and scavenging types of NOR, it is possible to cleave the N-O bond, forming N2O, without any extra protons or electrons. In a heme-copper oxidase, on the other hand, both a proton and an electron are needed to form N2O.

In addition to being an intermediate in the denitrification, NO is a toxic agent. Myoglobin in the oxy-form reacts with NO forming nitrate (NO3 -) at a high rate, which should make this enzyme an efficient NO scavenger. Peroxynitrite (ONOO-) is formed as a short-lived intermediate and isomerizes to nitrate through a radical reaction.

In the mechanism for pumping protons in cytochrome oxidase, thermodynamics, rather than structural changes, might guide protons to the heme propionate for further translocation.

The dioxygenation of arachidonic acid in prostaglandin endoperoxide H synthase forms the bicyclic prostaglandin G2, through a cascade of radical reactions. The mechanism proposed by Hamberg and Samuelsson is energetically feasible.

Place, publisher, year, edition, pages
Stockholm: Fysikum, 2006. 79 p.
enzyme catalysis, redox reactions, cytochrome oxidase, nitric oxide reductase, hyponitrous acid anhydride, peroxynitrite, myoglobin, prostaglandin synthase, PGHS, NO, N2O, O2, CO
National Category
Atom and Molecular Physics and Optics
urn:nbn:se:su:diva-863 (URN)91-7155-208-1 (ISBN)
Public defence
2006-03-17, sal FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00
Available from: 2006-02-20 Created: 2006-02-20Bibliographically approved

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