Probing reactivity of PQQ-dependent carbohydrate dehydrogenases using artificial electron acceptor.

The kinetic parameters of carbohydrate oxidation catalyzed by Acinetobacter calcoaceticus pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase (GDH) and Escherichia coli PQQ-dependent aldose sugar dehydrogenase (ASDH) were determined using various electron acceptors. The radical cations of organic compounds and 2,6-dichlorophenolindophenol are the most reactive with both enzymes in presence of glucose. The reactivity of dioxygen with ASDH is low; the bimolecular constant k (ox) = 660 M(-1) s(-1), while GDH reactivity with dioxygen is even less.

Pyrroloquinoline quinone-dependent carbohydrate dehydrogenase: activity enhancement and the role of artificial electron acceptors.

Pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase (PQQ-GDH) offers a variety of opportunities for applications, e.g. in highly sensitive biosensors and electrosynthetic reactions.

Antioxidants determination with laccase.

The spectrophotometric method of antioxidants determination using recombinant laccase Polyporus pinsitus (rPpL) and Myceliophthora thermophila (rMtL) was developed. The method includes simultaneous oxidation of the antioxidant and high reactive laccase substrate producing chromophoric radical cation. As laccase substrates ABTS and other high reactive phenoxazine derivatives: 2-phenoxazin-10-yl-ethanol (PET), 3-phenoxazin-10-yl-propane-1-sulfonic acid (PPSA) and 3-phenoxazin-10-yl-propionic acid (PPA) were used.

Laccase-catalysed iodide oxidation in presence of methyl syringate.

The kinetics of potassium triiodide (KI(3)) formation during fungal laccase action was investigated in presence of methyl syringate (MS). The recombinant forms of Polyporus pinsitus (rPpL), Myceliophthora thermophila (rMtL), Coprinus cinereus (rCcL), and Rhizoctonia solani (rRsL) laccases were used. The triiodide formation rate reached 6.