Kinetic characterisation and thermal inactivation study of red alga (Mastocarpus stellatus) peroxidase

Red Cabbage (Brassica oleracea) as a New Source of High-Thermostable Peroxidase

“…The optimum pH was found to be 4.0 (Table 1), which is similar to that obtained for marula fruit 37 and lower than that obtained for melon, 38 pepper, 24 or red alga. 17 The activating or inhibiting effect of SDS on different enzymes, including PPO and POD, has been widely described. In the case of POD, SDS showed an inhibitory effect in many cases.…”

“…These results are in accordance with those obtained for other PODs from potato or carrot, 51 pepper, 24 grape, 39 and red alga. 17 From the slopes of these lines, the inactivation rate constants (k) were calculated by linear regression according to the following equation: 51 …”

“…The activation energies (E a ) were calculated from the slopes of the Arrhenius plot by the following equation: 51 (5) where R is the gas constant (8.314 J mol −1 K −1 ) and T is the temperature in K. This linear fit contrasts with the curvature obtained for other vegetables, including potato and carrot PODs, 51 green bean lipoxygenase, 52 pea seed lipoxygenase, 53 and grape POD, 39 but agrees with that obtained for pepper POD 24 and red alga POD. 17 The explanation for this linearity in the Arrhenius plot is that the inactivation in both membranebound and soluble PODs occurs through a one temperaturedependent mechanism, such as protein unfolding. However, when a curvature in the Arrhenius plot is observed, the explanation is that the inactivation occurs through more than one mechanism, each with its own temperature dependence, and the overall temperature dependence is simply the sum of the individual processes.…”

Selective oxidation of enzyme extracts for improved quantification of peroxidase activity

“…The underestimate of enzyme activity may appear as a complete lack of peroxidase activity if the rate of (2) is much greater than that of reaction (1), such that ABTS• + is reduced immediately upon formation. Or it may reflect a fractional underestimate of peroxidase activity if rates of reactions (1) and (2) The modified assay addresses a problem that has been noted by many (e.g., [20,26,27,[38][39][40]). Compounds likely to interfere with the traditional ABTS-based peroxidase assay include a wide range of natural antioxidants.…”

“…A variety of methods exist for the determination of peroxidase activity, including those based on colorimetric [19][20], fluorometric [21], chemiluminescent [22], and electrochemical [23] detection. Among these, colorimetric detection is most commonly used as it is simple and economical [24].…”