Inactivation of Peroxidase by Ultraviolet–Visible Irradiation: Effect of pH and Melanoidin Content

Falguera, Víctor; Moulin, Anthony; Thévenet, Laurent; Ibarz, Albert

doi:10.1007/s11947-012-1019-y

Cited by 14 publications

(7 citation statements)

References 19 publications

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“…The activity of HRP was initially evaluated by the pyrogallol assay in dark conditions and in the presence of PM-K and PM-T at pH 6 and pH 7, respectively. , As reported in Table (entry 1 versus entries 4 and 6), the enzymatic activity was not significantly modified with respect to the reference (HRP alone) in the presence of pheomelanin samples at pH 7, while a slight decrease of the enzymatic activity was observed at pH 6, probably due to the occurrence of supramolecular interactions between HRP and pheomelanin (Table , entry 2 versus entries 5 and 7). , In a similar way, HRP retained the original activity after UVA irradiation at pH 7 for 24 h at 27 °C (Table , entry 3 versus entry 1) …”

Section: Resultsmentioning

confidence: 96%

First Evidence of Pheomelanin-UVA-Driven Synthesis of Pummerer’s Ketones by Peroxidase-Mediated Oxidative Coupling of Substituted Phenols

et al. 2022

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Photoexcitation of pheomelanin produces high-energy singlet oxygen and the superoxide anion, which are reactive species in damage of cellular targets. In principle, these species can be involved in processes of synthetic utility when adequate experimental conditions are defined. Here, we describe that pheomelanin performs as a selective UVA antenna for the horseradish peroxidase oxidative coupling of substituted phenols to biologically active Pummerer’s ketones under 2-methyltetrahydrofuran/buffer biphasic conditions. In this system, singlet oxygen is scavenged by conversion of 2-methyltetrahydrofuran into the corresponding organic hydroperoxide, while the superoxide anion is dismutated into hydrogen peroxide. Both these intermediates are able to oxidize the active site of horseradish peroxidase triggering the oxidative coupling reaction. Trimer derivatives, produced by addition of phenoxy radicals on preformed Pummerer’s ketones were also isolated, suggesting the possibility to further improve the structural complexity of the reaction products.

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Section: Resultsmentioning

confidence: 96%

First Evidence of Pheomelanin-UVA-Driven Synthesis of Pummerer’s Ketones by Peroxidase-Mediated Oxidative Coupling of Substituted Phenols

et al. 2022

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“…The different behaviour of POD activity for both temperatures is in line with the available studies for UV irradiation of fruit juices. While Falguera, Garza, et al (2013) found initial POD activation in buffer solutions, only POD inactivation was observed for orange juices by Sampedro and Fan (2014), apples by , grape musts by Falguera, Moulin, Thevenet, and Ibarz (2013) and pears by Falguera et al (2014). According to the different behaviour found, activation might always take place, but when the inactivation process is fast enough, the activation cannot be observed.…”

Section: Enzymatic Activitiesmentioning

confidence: 99%

Effect of UV–Vis irradiation on enzymatic activities and the physicochemical properties of nectarine juices from different varieties

Aguilar

Ibarz

Garvín

et al. 2016

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“…For this purpose, a proportion of 1 mL of C6H8O7 (0.2M): 2.45 mL of Na2HPO4 (0.4 M) was mixed. The POD activity was evaluated using pyrogallol (C6H6O3) (Sigma-Aldrich, India) as the substrate as described by (Augusto et al, 2015;Falguera et al, 2013), with a few modifications. In each assay, 1.5 mL of coconut water, 1 mL of buffer solution at pH 6.0 and 320 μL of 5% (m/v) pyrogallol solution was mixed in a quartz cuvette with a 1 cm light path.…”

Section: Enzyme Activity Evaluationmentioning

confidence: 99%

The ultrasound technology for modifying enzyme activity

2016

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Enzymes are protein complexes compounds widely studied and used due to their ability to catalyze reactions. The food processing mainly aims the inactivation of enzymes due to various undesirable effects. However, there are many processes that can be optimized by its catalytic activity. In this context, different technologies have been applied both to inactivate or to improve the enzymes efficiency. The Ultrasound technology emerges as an alternative mainly applied to achieve the enzyme inactivation. On the contrary, very few investigations show the ability of this technology under certain conditions to achieve the opposite effect (i.e. increase the catalytic activity of enzymes). The objective of this study was to correlate the ultrasonic energy delivered to the sample (J/mL) with the residual enzymatic activity and explain the possible mechanisms which results in the enzymatic activation/inactivation complex behavior. The activity of POD in coconut water was evaluated as a model. The enzymatic activity initially increased, followed by reduction with a trend to enzyme inactivation. This complex behavior is directly related to the applied ultrasonic energy and their direct mechanical effects on the product, as well as the effect in the enzymatic infinite intermediate states and its structural conformation changes. The obtained results are useful for both academic and industrial perspectives.

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Inactivation of Peroxidase by Ultraviolet–Visible Irradiation: Effect of pH and Melanoidin Content

Cited by 14 publications

References 19 publications

First Evidence of Pheomelanin-UVA-Driven Synthesis of Pummerer’s Ketones by Peroxidase-Mediated Oxidative Coupling of Substituted Phenols

First Evidence of Pheomelanin-UVA-Driven Synthesis of Pummerer’s Ketones by Peroxidase-Mediated Oxidative Coupling of Substituted Phenols

Effect of UV–Vis irradiation on enzymatic activities and the physicochemical properties of nectarine juices from different varieties

The ultrasound technology for modifying enzyme activity

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