Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
Photooxidation of Tetrahydrobiopterin under UV Irradiation : Possible Pathways and Mechanisms. / Buglak, Andrey A.; Telegina, Taisiya A.; Lyudnikova, Tamara A.; Vechtomova, Yulia L.; Kritsky, Mikhail S.
в: Photochemistry and Photobiology, Том 90, № 5, 2014, стр. 1017-1026.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
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TY - JOUR
T1 - Photooxidation of Tetrahydrobiopterin under UV Irradiation
T2 - Possible Pathways and Mechanisms
AU - Buglak, Andrey A.
AU - Telegina, Taisiya A.
AU - Lyudnikova, Tamara A.
AU - Vechtomova, Yulia L.
AU - Kritsky, Mikhail S.
PY - 2014
Y1 - 2014
N2 - Tetrahydrobiopterin (H(4)Bip) is a cofactor for several key enzymes, including NO synthases and aromatic amino acid hydroxylases (AAHs). Normal functioning of the H(4)Bip regeneration cycle is extremely important for the work of AAHs. Oxidized pterins may accumulate if the H(4)Bip regeneration cycle is disrupted or if H(4)Bip autoxidation occurs. These oxidized pterins can photosensitize the production of singlet molecular oxygen O-1(2) and thus cause oxidative stress. In this context, we studied the photooxidation of H(4)Bip in phosphate buffer at pH 7.2. We found that UV irradiation of H(4)Bip affected its oxidation rate (quantum yield phi(300) = (2.7 +/- 0.4) x 10(-3)). The effect of UV irradiation at =350nm on H(4)Bip oxidation was stronger, especially in the presence of biopterin (Bip) (phi(350) = (9.7 +/- 1.5) x 10(-3)). We showed that the rate of H(4)Bip oxidation linearly depends on Bip concentration. Experiments with KI, a selective quencher of triplet pterins at micromolar concentrations, demonstrated that the oxidation is sensitized by the triplet state biopterin (3)Bip. Apparently, electron transfer sensitization (Type-I mechanism) is dominant. Energy transfer (Type-II mechanism) and singlet oxygen generation play only a secondary role. The mechanisms of H(4)Bip photooxidation and their biological meaning are discussed.
AB - Tetrahydrobiopterin (H(4)Bip) is a cofactor for several key enzymes, including NO synthases and aromatic amino acid hydroxylases (AAHs). Normal functioning of the H(4)Bip regeneration cycle is extremely important for the work of AAHs. Oxidized pterins may accumulate if the H(4)Bip regeneration cycle is disrupted or if H(4)Bip autoxidation occurs. These oxidized pterins can photosensitize the production of singlet molecular oxygen O-1(2) and thus cause oxidative stress. In this context, we studied the photooxidation of H(4)Bip in phosphate buffer at pH 7.2. We found that UV irradiation of H(4)Bip affected its oxidation rate (quantum yield phi(300) = (2.7 +/- 0.4) x 10(-3)). The effect of UV irradiation at =350nm on H(4)Bip oxidation was stronger, especially in the presence of biopterin (Bip) (phi(350) = (9.7 +/- 1.5) x 10(-3)). We showed that the rate of H(4)Bip oxidation linearly depends on Bip concentration. Experiments with KI, a selective quencher of triplet pterins at micromolar concentrations, demonstrated that the oxidation is sensitized by the triplet state biopterin (3)Bip. Apparently, electron transfer sensitization (Type-I mechanism) is dominant. Energy transfer (Type-II mechanism) and singlet oxygen generation play only a secondary role. The mechanisms of H(4)Bip photooxidation and their biological meaning are discussed.
KW - AQUEOUS-SOLUTION
KW - MOLECULAR-OXYGEN
KW - OXIDATION
KW - AUTOXIDATION
KW - PTERIN
KW - PHOTOCHEMISTRY
KW - IDENTIFICATION
KW - BIOSYNTHESIS
KW - REDUCTION
KW - VITILIGO
U2 - 10.1111/php.12285
DO - 10.1111/php.12285
M3 - статья
VL - 90
SP - 1017
EP - 1026
JO - Photochemistry and Photobiology
JF - Photochemistry and Photobiology
SN - 0031-8655
IS - 5
ER -
ID: 74221326