/pdf/purification-and-characterization-2y44lhntkf.pdf

Purification and Characterization

Copper is an essential trace element in living systems, present in the parts per million concentration range. It is a key cofactor in a diverse array of biological oxidation-reduction reactions. These involve either outer-sphere electron transfer, as in the blue copper proteins and the Cu{sub A} site of cytochrome oxidase and nitrous oxide redutase, or inner-sphere electron transfer in the binding, activation, and reduction of dioxygen, superoxide, nitrite, and nitrous oxide. Copper sites have historically been divided into three classes based on their spectroscopic features, which reflect the geometric and electronic structure of the active site: type 1 (T1) or blue copper, type 2 (T2) or normal copper, and type 3 (T3) or coupled binuclear copper centers. 428 refs.

Multicopper Oxidases and Oxygenases

/pdf/the-structure-and-function-of-fungal-laccases-25lk9xuy0a.pdf

The structure and function of fungal laccases

Phosphoenolpyruvate:carbohydrate phosphotransferase systems of bacteria.

https://depositonce.tu-berlin.de/bitstream/11303/5674/1/c2np20085f.pdf

Ribosomally synthesized and post-translationally modified peptide natural products: Overview and recommendations for a universal nomenclature

Glucose electrodes were prepared by wiring quinoprotein glucose dehydrogenase, GDH (EC 1.1.99.17) to glassy carbon with an osmium complex containing redox-conducting epoxy network. Their current density at 70 mM glucose concentration reached 1.8 mA cm -2 when 15 μg cm -2 of the enzyme having an activity of 250 units mg -1 was applied to the electrode. Under the same conditions, electrodes made with glucose oxidase (GOX) of similar activity (250 units mg -1 ) had a maximum current density of 0.66 mA cm -2 . The maximum current density was reached with 8% GDH in the redox polymer film

High current density "wired" quinoprotein glucose dehydrogenase electrode

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2879%2980584-0

Glucose dehydrogenase from Acinetobacter calcoaceticus: a 'quinoprotein'.

Bovine serum amine oxidase: a mammalian enzyme having covalently bound PQQ as prosthetic group

The presently best known and largest group of quinoproteins consists of enzymes using the cofactor 2,7,9-tricarboxy-1H-pyrrolo[2,3-f]quinoline-4, 5-dione (PQQ), a compound having a pyrrole ring fused to a quinoline ring with an o-quinone group in it. Representatives of this group are found among the bacterial, NAD(P)-independent, periplasmic dehydrogenases. Despite their high midpoint redox potential, the overall behaviour of quinoprotein dehydrogenases is similar to that of their counterparts, those using a flavin cofactor or a nicotinamide coenzyme. Apart from an exceptional Gram-positive one, the sole organisms where the presence of PQQ has really been established are Gram-negative bacteria. Evidence for the occurrence of covalently bound PQQ is lacking since it has now been shown that several enzymes previously considered to contain this prosthetic group do not in fact do so.

https://febs.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1432-1033.1991.tb16183.x

Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan-tryptophan quinone.

Soluble glucose dehydrogenase (s-GDH; EC 1.1.99.17) is a classical quinoprotein which requires the cofactor pyrroloquinoline quinone (PQQ) to oxidize glucose to gluconolactone. The reaction mechanism of PQQ-dependent enzymes has remained controversial due to the absence of comprehensive structural data. We have determined the X-ray structure of s-GDH with the cofactor at 2.2 A resolution, and of a complex with reduced PQQ and glucose at 1.9 A resolution. These structures reveal the active site of s-GDH, and show for the first time how a functionally bound substrate interacts with the cofactor in a PQQ-dependent enzyme. Twenty years after the discovery of PQQ, our results finally provide conclusive evidence for a reaction mechanism comprising general base-catalyzed hydride transfer, rather than the generally accepted covalent addition-elimination mechanism. Thus, PQQ-dependent enzymes use a mechanism similar to that of nicotinamide- and flavin-dependent oxidoreductases.

/pdf/structure-and-mechanism-of-soluble-quinoprotein-glucose-5934pjm6tg.pdf

Johannis A. Duine

Papers

High current density "wired" quinoprotein glucose dehydrogenase electrode

Glucose dehydrogenase from Acinetobacter calcoaceticus: a 'quinoprotein'.

Bovine serum amine oxidase: a mammalian enzyme having covalently bound PQQ as prosthetic group

Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan-tryptophan quinone.

Structure and mechanism of soluble quinoprotein glucose dehydrogenase.