INVESTIGADORES
THOMAS Andres Hector
congresos y reuniones científicas
Título:
Degradation of α-Melanocyte-Stimulating Hormone photosensitized by Pterin
Autor/es:
CAROLINA CASTAÑO; CAROLINA LORENTE; NATHALIE MARTINS-FROMENT ; ESTHER OLIVEROS; ANDRÉS H. THOMAS
Lugar:
Córdoba
Reunión:
Congreso; 16th International Congress on Photobiology; 2014
Institución organizadora:
International Union of Photobiology
Resumen:
Oxidized pterins,
efficient photosensitizers under UV-A irradiation, accumulate in the skin of
patients suffering from vitiligo, a chronic depigmentation disorder. In this
work, we have investigated the ability of pterin (Ptr), the parent compound of
oxidized pterins,to photosensitize the oxidation of the peptide
α-melanocyte-stimulating hormone (α-MSH), which stimulates the production and
release of melanin by melanocytes in skin and hair. Our results show that Ptr
is able to photoinduce the degradation of α-MSH upon UV-A irradiation and that
the reaction is initiated by an electron transfer from the peptide to the triplet
excited stated of Ptr. The photosensitized process leads to the oxidation of
the peptide and to the degradation of, at least, tryptophan (Trp) and tyrosine
(Tyr) residues. It can thus be inferred that the incorporation of oxygen atoms
takes place at least in these α-MSH residues. In addition, the dimerization of
the peptide was also observed and dimers of theTyr radical were detected in the
treated peptide, indicating that Ptr may photoinduce crosslinking of
peptides.The evolution of the reactions was followed by UV-Vis spectrometry and
products were analyzed by HPLC, UPLC-MS and
fluorescence.
AcknowledgmentsConsejo
Nacional de Investigaciones Cientificas y Técnicas (CONICET-Grant PIP 0425) and
Universidad Nacional de La Plata (UNLP-Grant X586)
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