Selective protein modification by the hydroperoxide intermediate in a photoprotein, aequorin

During the course of protein modification program, we employed a recombinant aequorin, the apo-protein reconstituted with coelenterazine, and found out that the photolytic hyperperoxide modified three –S–SCH2CHOHCHOHCH2SH groups to –S–SCH2CHOHCHCH–SO)H or –S–SCH2CHOHCHCH–S(O)OH of terminal DTT connected to cysteine residues of the C145, C152 and C180, which turned out to locate near the chromophore.

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