Avoiding One-Electron Oxidation of Biomolecules by 3,4-Dihydroxy-L-Phenylalanine (DOPA).
Photochem Photobiol
; 99(2): 570-579, 2023 03.
Article
em En
| MEDLINE
| ID: mdl-36114810
It has been proposed that 3,4-dihydroxy-L-phenylalanine (DOPA) has antioxidant properties, and thus, the objective of this work was to evaluate the effect of adding DOPA during the photosensitized oxidation of tyrosine (Tyr), tryptophan (Trp), histidine (His), 2'-deoxyguanosine 5'-monophosphate (dGMP) and 2'-deoxyadenosine 5'-monophosphate (dAMP). It was observed that, upon pterin-photosensitized degradation of a given biomolecule in acidic aqueous solutions, the rate of the biomolecule consumption decreases due to the presence of DOPA. Although DOPA deactivates the excited states of pterin (Ptr), biomolecules do as well, being the bimolecular quenching constants in the diffusional control limit, indicating that DOPA antioxidant mechanism is not a simple deactivation of Ptr excited states. Laser flash photolysis experiments provide evidence of the formation of DOPA radical (DOPA(-H)⢠, λMAX 310 nm), which is formed in a timescale longer than Ptr triplet excited state (3 Ptr*) lifetime, ruling out its formation in a reaction between DOPA and 3 Ptr*. The experimental results presented in this work indicate that the observed decrease on the rate of each biomolecule consumption due to the presence of DOPA is through a second one-electron transfer reaction from DOPA to the biomolecule radicals.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Elétrons
/
Antioxidantes
Idioma:
En
Revista:
Photochem Photobiol
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Estados Unidos