Fig. 1.

Lactoperoxidase-mediated TNB degradation. The effect of low and high H₂O₂ concentrations on the (pseudo-)halogenating enzyme activity was tested at 37 °C and pH 7.4. Thereby (pseudo-) physiological conditions in the oral cavity were imitated by using 5 nM LPO and 2 mM SCN⁻. The columns correspond to the sole presence of H₂O₂ (white), the additionally presence of LPO (gray) and the whole LPO–H₂O₂–SCN⁻ system (black), respectively. The fourth column (light gray) shows the corresponding net effect of the ⁻OSCN mediated TNB degradation. At higher H₂O₂ concentrations a significant lower net LPO activity was found. Mean and standard deviation of n=3–6 experiments are given.