    1.14.14.9 | -999 |
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in the absence of 4-hydroxyphenylacetate, the rate constant for the formation of C4a-hydroperoxy-FMN is unaffected at pH 6.2-9.9. The rate constant for the following H2O2 elimination step increases with higher pH, consistent with a pKa above 9.4. In the presence of 4-hydroxyphenylacetate, the rate constants for the formation of C4a-hydroperoxy-FMN and the ensuing hydroxylation step are not significantly affected by the pH. In contrast, the following steps of C4a-hydroxy-FMN dehydration to form oxidized FMN occur through two pathways that are dependent on the pH of the reaction. One pathway, dominant at low pH, allows the detection of a C4a-hydroxy-FMN intermediate, whereas the pathway dominant at high pH produces oxidized FMN without an apparent accumulation of the intermediate. Both pathways efficiently catalyze hydroxylation without generating significant amounts of wasteful H2O2 at pH 6.2-9.9 |
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