PHOTOSENSITIZATION BY RIBOFLAVIN: INHIBITING EFFECT OF OXIDATION PRODUCTS

E.L.Lozovskaya and I.I.Sapezhinskii

 

Institute of Biochemical Physics,

Russian Academy of Sciences,

4 Kosygin Street, Moscow, 117977

e-mail: efrem@glas.apc.org

 

Introduction

Riboflavin is an important vitamin and well-known photosensitizer. However, under some conditions, its photosensitizing action is affected by the inhibiting action of photooxidation products. We observed this phenomenon in the course of oxidation of glycyl-tryptophan (Gly-Trp).

Peptide Gly-Trp is a convenient model for study of protein photooxidation. Photooxidation of Gly-Trp is accompanied with chemiluminescence (CL).

The study was carried out in a model system based on the measurement of photoinduced CL in aqueous solution. Chemiluminescence occurs due to decay of one of the oxidation products, dioxetane (D). Decay of the dioxetane results in product (P) in excited state:

D P, P* P + hn CL

This product is presumably, kynurenin-type compound.

D, L - kynurenin