Photosensitization of Singlet Oxygen Formation by Pterins and Flavins. Time-Resolved Studies of Oxygen Phosphorescence under Laser Excitation

S. Yu. Egorov^1,2, A. A. Krasnovsky, Jr.^1,2*, M. Ye. Bashtanov¹, E. A. Mironov³, T. A. Ludnikova¹, and M. S. Kritsky¹

¹Bach Institute of Biochemistry, Russian Academy of Sciences, Leninkii pr. 33, Moscow, 117021 Russia; fax: (095) 954-2732; E-mail: inbio@glas.apc.org

²School of Biology, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 939-0064; E-mail: etis@etis.msu.ru

³Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, ul. Vavilova 28, Moscow, 117813 Russia; fax: (095) 135-5085

^* To whom correspondence should be addressed.

Received April 12, 1999; Revision received May 5, 1999

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To elucidate the biochemical roles of singlet molecular oxygen (¹O₂) in the light-dependent reactions photosensitized by biological blue-light photoreceptors, time-resolved measurements of photosensitized ¹O₂ phosphorescence (1270 nm) were performed in air-saturated aqueous (D₂O) solutions of pterins (2-amino-4-hydroxy-6,7-dimethylpteridine (DMP) and 2-amino-4-hydroxy-6-tetrahydroxybutyl-(D-arabo)pteridine (TOP)) and flavins (riboflavin and flavin mononucleotide (FMN)) under excitation with nitrogen laser (337.1 nm) pulses. The ¹O₂ quantum yields were found to be 0.16, 0.20, 0.50, and 0.50 for DMP, TOP, riboflavin, and FMN, respectively. The data indicate that pterins and flavins are rather efficient photosensitizers of ¹O₂ production that might be important for their photobiological functions.

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KEY WORDS: pterins, flavins, photoreceptors, singlet oxygen

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