Figure 4. Mt TPx activity measured by changes in Mt TrxB fluorescence in the presence of H2O2. Pre-reduced MtTrxB (4.5 |M) was mixed with H2O2 (1.6|M) in phosphate buffer 50mM pH 7.4 and 25 °C, either with no further addition (a), or in the presence of 0.7 |M wild type MtTPx (b) or 0.7 |M C60S MtTPx (c) and changes in fluorescence intensity (\ex = 280 nm, \em > 335 nm) were registered by stopped-flow techniques. Initial rates of MtTrxB reduction by wild-type MtTPx were calculated from the initial slope of fluorescence intensity change and a calibration curve relating fluorescence changes with reduced MtTrx concentration. The inset shows the emission spectrum (\ex = 280 nm) of MtTrxB (2.5 |M) before (Trx-S2) and 1 minute after the addition of 1 mM DTT (Trx-SH2)

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