Peroxidase catalyzed phenolic compounds oxidation in presence of surfactant Dynol 604: A kinetic investigation

Kinetic Study of Peroxidase-Catalyzed Oxidation of 2-Hydroxyanthracene and 9-Phenanthrol in Presence of Biosurfactant Escin

The kinetics of fungal peroxidase-catalyzed 2-hydroxyanthracene and 9-phenanthrol oxidation was investigated in presence of biosurfactant escin at pH 5.5 and 25 °C. The kinetic measurements were performed using the fluorimetric method and the critical micelle concentration (CMC) of escin was determined using the dynamic light scattering technique. Inactivation of peroxidase was observed in absence of biosurfactant escin. It was shown that escin, used in concentrations lower than CMC, decreases or completely stops the peroxidase inactivation and increases the conversion of 2-hydroxyanthracene as well as of 9-phenanthrol. The environmentally friendly method of peroxidase-catalyzed 2-hydroxyanthracene and 9-phenanthrol oxidation in presence of biosurfactant Escin has an advantage over traditional decontamination methods due to their less environmental impact.

Effects of rhamnolipid biosurfactant JBR425 and synthetic surfactant surfyno1465 on the peroxidase-catalyzed oxidation of 2-naphthol

The kinetics of the recombinant Coprinus cinereus peroxidase-catalyzed 2-naphthol oxidation was investigated in the presence of rhamnolipid biosurfactant JBR425 and synthetic surfactant Surfynol465 at pH 5.5 and 250C, with concentrations of (bio)surfactants both less than critical micelle concentrations (CMC) and larger than CMC. It was shown that monomers of JBR425 as well as monomers of Surfynol465 had an enhancing effect on the conversion of 2-naphthol in dose response manner and did not influence the initial rate of 2-naphthol oxidation. The results were accounted by a scheme, which contains a stadium of enzyme inhibition by oligomeric 2-naphthol oxidation products. The action of the biosurfactant's (or synthetic surfactant's) monomers was explained by avoidance of the enzyme active center clothing with oligomers. Similar results have demonstrated the potential of rhamnolipid biosurfactant JBR425 due to its biodegradability. When biosurfactants' concentrations are larger than CMC, (bio)surfactants have an opposite effect on the oxidation of 2-naphthol by peroxidase.

Selective electrochemical recognition of the α-naphthol isomer and in situ immobilization of naphthoquinones for tunable electrocatalysis

Fits like a glove: Separationless and selective electrochemical oxidation of the α-naphthol (α-NAP) isomer yields naphthoquinone species on the surface of multiwalled carbon nanotubes, which can further catalyze the electro-oxidation of NADH and hydrazine at different potentials. The β-NAP isomer failed to show any such electro-oxidation.

Highly sensitive detection of α-naphthol based on G-DNA modified gold electrode by electrochemical impedance spectroscopy

A highly sensitive, reusable G-rich DNA sensor was reported for the detection of α-naphthol by electrochemical impedance spectroscopy (EIS). Specifically, a single-stranded G-rich DNA was self-assembled on the electrode and transformed into K(+)-stabilized G-quadruplex, which could catalyze H2O2-mediated oxidation of α-naphthol (with hemin as a cofactor) to 1, 4-naphthoquinone precipitated on the DNA films. Due to the insolubility of 1, 4-naphthoquinone, the charge transfer resistance (RCT) was increased to maximum within 15 min. Depending on the difference in charge transfer resistance change (ΔRCT), the α-naphthol could be detected with the detection limit of 0.1 nM in Tris-ClO4 buffer solution (20mM, pH=7.4). Moreover, the sensor demonstrated a high selectivity over other selected phenolic compounds. The performance of the sensor in the real lake water was also explored with the detection limit of 0.8 nM. Finally, the regeneration of the sensor was investigated, which allowed for reuse more than 4 cycles with a mean recovery of 94% of the original signal.