Photosensitized Dimerization of Tyrosine: The Oxygen Paradox †

Autor:	M. Laura Dántola, Andrés H. Thomas, Jael R. Neyra Recky, Carolina Lorente
Rok vydání:	2021
Předmět:	Singlet Oxygen Chemistry chemistry.chemical_element General Medicine Photochemistry Biochemistry Oxygen Pterins chemistry.chemical_compound Excited state Tyrosine Molecular oxygen Physical and Theoretical Chemistry Pterin Dimerization Oxidation-Reduction
Zdroj:	Photochemistry and Photobiology. 98:687-695
ISSN:	1751-1097 0031-8655
Popis:	In electron-transfer initiated photosensitization processes, molecular oxygen (O2 ) is not involved in the first bimolecular event, but almost always participates in subsequent steps giving rise to oxygenated products. An exception to this general behavior is the photosensitized dimerization of tyrosine (Tyr), where O2 does not participate as a reactant in any step of the pathway yielding Tyr dimers (Tyr2 ). In the pterin (Ptr) photosensitized oxidation of Tyr, O2 does not directly participate in the formation of Tyr2 and quenches the triplet excited state of Ptr, the reactive species that initiates the process. However, O2 is necessary for the dimerization, phenomenon that we have named as the oxygen paradox. Here, we review the literature on the photosensitized formation of Tyr2 and present results of steady-state and time resolved experiments, in search of a mechanistic model to explain the contradictory role of O2 in this photochemical reaction system.
Databáze:	OpenAIRE
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