INVESTIGADORES
DANTOLA Maria Laura
congresos y reuniones científicas
Título:
Photodimerization of 6-hydroxymethyl-7,8-dihydropterin in aqueous solution under UV-A irradiation
Autor/es:
ESTHER OLIVEROS; M. LAURA DÁNTOLA; ANDRÉ M. BRAUN; ANDRÉS H. THOMAS; CAROLINA LORENTE
Lugar:
Bad Hofgastein
Reunión:
Congreso; Central European Conference on Photochemistry (CECP2012); 2012
Resumen:
Pterins, heterocyclic compounds
widespread in biological systems, are derived from 2-aminopteridin-4(1H)-one or pterin. . The most common
pterin derivatives are 6-substituted compounds and exist in different oxidation
states: oxidized (or aromatic) pterins and reduced pterins. Within the latter
group, 7,8-dihydropterins and 5,6,7,8-tetrahydropterins are most important due
to their biological activity, e.g.
tetrahydrofolic acid is a coenzyme in many reactions,
especially in the metabolism of amino acids and nucleic acids [1]. All organisms require reduced folate
cofactors for the synthesis of a variety of metabolites. 7,8-Dihydro-6-hydroxymethylpterin-pyrophosphokinase
catalyzes the attachment of pyrophosphate to 6-hydroxymethyl-7,8-dihydropterin (H2Hmp)
to form 6-hydroxymethyl-7,8-dihydropteridine pyrophosphate, an important
intermediate in the biosynthesis of folate.
Little is known about the photochemical
reactivity of H2Hmp.
In this work, the kinetics of H2Hmp consumption under UV-A
irradiation in aqueous solutions at physiological pH were followed by UV/vis
spectrophotometry and HPLC. H2O2 production was
quantified by enzymatic methods. Products were analyzed by electrospray
ionization mass spectrometry.
Excitation of H2Hmp leads
to the formation of a dimer with a molecular mass equal to exactly twice that
of the substrate. The quantum yield of H2Hmp consumption (F-H2Hmp = 0.10 ± 0.02) was independent of O2
and reactant concentrations. Mechanistic and potential biological implications
of the results obtained will be discussed.
[1]
R. Blakely, S. Benkovic, Chemistry and
Biochemistry of Pterins. In: Folates and Pterins, Vol. 2. John Wiley &
Sons, New York, 1984.