Pyrroloquinoline quinone maintains redox activity when bound to a DNA aptamer

Emahi, Ismaila; Mulvihill, Isabel M.; Baum, Dana A.

doi:10.1039/c4ra11052h

Cited by 10 publications

(7 citation statements)

References 44 publications

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“…SHE) than NAD + (−0.320 V; vs . SHE) and is capable of carrying out thousands of redox catalytic cycles at neutral pH and moderate temperatures 1 34 35 36 . Even though other quinone biofactors are liable to either self-oxidize or condense into an inactive form, PQQ is relatively stable and does not easily polymerize during redox cycling.…”

Section: Discussionmentioning

confidence: 99%

Identification of lactate dehydrogenase as a mammalian pyrroloquinoline quinone (PQQ)-binding protein

Akagawa

Minematsu

Shibata

et al. 2016

Sci Rep

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Pyrroloquinoline quinone (PQQ), a redox-active o-quinone, is an important nutrient involved in numerous physiological and biochemical processes in mammals. Despite such beneficial functions, the underlying molecular mechanisms remain to be established. In the present study, using PQQ-immobilized Sepharose beads as a probe, we examined the presence of protein(s) that are capable of binding PQQ in mouse NIH/3T3 fibroblasts and identified five cellular proteins, including l-lactate dehydrogenase (LDH) A chain, as potential mammalian PQQ-binding proteins. In vitro studies using a purified rabbit muscle LDH show that PQQ inhibits the formation of lactate from pyruvate in the presence of NADH (forward reaction), whereas it enhances the conversion of lactate to pyruvate in the presence of NAD+ (reverse reaction). The molecular mechanism underlying PQQ-mediated regulation of LDH activity is attributed to the oxidation of NADH to NAD+ by PQQ. Indeed, the PQQ-bound LDH oxidizes NADH, generating NAD+, and significantly catalyzes the conversion of lactate to pyruvate. Furthermore, PQQ attenuates cellular lactate release and increases intracellular ATP levels in the NIH/3T3 fibroblasts. Our results suggest that PQQ, modulating LDH activity to facilitate pyruvate formation through its redox-cycling activity, may be involved in the enhanced energy production via mitochondrial TCA cycle and oxidative phosphorylation.

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Section: Discussionmentioning

confidence: 99%

Identification of lactate dehydrogenase as a mammalian pyrroloquinoline quinone (PQQ)-binding protein

Akagawa

Minematsu

Shibata

et al. 2016

Sci Rep

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“…All buffers contained 10 mM CaCl 2 and 50 mM MgCl 2 , and 200 mM KCl, except for our phosphate buffer, which did not contain the divalent metal ions. These metal ion conditions were chosen based on our recent report of DNA aptamers for PQQ, 10 but also represent conditions that could be used with other biomolecules. Calcium is well-known to enhance the enzyme activity of several PQQ-containing dehydrogenases 11,19 and has been investigated with immobilized PQQ on gold and platinum electrodes.…”

Section: Resultsmentioning

confidence: 99%

“…They can also affect how PQQ binds to other functional biomolecules, such as aptamers, and can be responsible for maintaining or enhancing the catalytic ability of the PQQ-biomolecule complex. [10][11][12][13] Thus using phosphate buffers to study the electrochemistry of protein or nucleic acid bound-PQQ could present some challenges. Using non-phosphate, physiological buffers could overcome these issues and also expand our understanding of the electrochemical behavior of PQQ in solution.…”

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confidence: 99%

Electrochemistry of Pyrroloquinoline Quinone (PQQ) on Multi-Walled Carbon Nanotube-Modified Glassy Carbon Electrodes in Biological Buffers

Emahi

Mitchell

Baum

2017

J. Electrochem. Soc.

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Pyrroloquinoline quinone (PQQ) is an important electrocatalyst and redox cofactor for many enzymes used in bioanalytical applications. Careful selection of electrode modifications and buffer compositions is required due to PQQ's tendency to be irreversibly reduced on bare electrodes and the strong effect of pH on its electrochemistry. Multi-walled carbon nanotubes (MWCNTs) can effectively modify glassy carbon electrodes, but PQQ's behavior at these surfaces has not been investigated. While phosphate buffers have been used extensively to characterize PQQ's electrochemistry, phosphate buffers can act as chelating agents for important metal ions needed by PQQ and biomolecules. Different physiological buffers could overcome these challenges and expand the buffer options for biofuel cells. Using cyclic voltammetry, we studied PQQ in HEPES, MOPS, TRIS, and phosphate buffers at pH 7 with MWCNT-modified electrodes. While there were no significant differences in PQQ's behavior with the various buffers, the ionic composition of the non-phosphate buffers was very important. We observed that K + and Mg 2+ were the most influential ions for the reversible reduction-oxidation of PQQ. PQQ's electrochemistry was also affected by the length of and the functional groups on the MWCNTs, indicating that the electron transfer kinetics were quite sensitive to the surface chemistry of the electrodes. Pyrroloquinoline quinone (PQQ) is a redox cofactor found in the active sites of a number of enzymes. Most of these quinoproteins are dehydrogenases capable of catalyzing the oxidation of a broad range of substrates, such as alcohols, acids, aldehydes and sugars. 1 PQQ-dependent glucose dehydrogenase, for example, is capable of oxidizing several mono-and disaccharides, including glucose, maltose, lactose, galactose, xylose and mannose.1 The uniqueness of the quinoproteins and their broad substrate specificities have led to their use in bioanalytical applications, including biosensors and biofuel cells.In the absence of an enzyme, PQQ itself is capable of catalyzing redox reactions, including the oxidation of thiols, 2,3 amino acids, 4 and the redox cofactor nicotinamide adenine dinucleotide (NAD + ). 5The electrochemistry of PQQ has been studied quite extensively in both solution and immobilized forms via cyclic voltammetry (CV) and potentiometric titration studies. 6,7 These studies can be challenging due to the pH dependence of the redox potentials. 6,8,9 Using a cystamine-monolayer Au-modified electrode, Katz et al.6 studied the electrochemistry of PQQ in solution using CV and reported the change in potential with pH to be about 60 mV pH −1 at pH < 6.2; 30 mV pH −1 at 6.2 < pH < 8.6; and about 60 mV pH −1 at pH > 8.6. In another study using PQQ immobilized on few-walled carbon nanotube (FWCNT)-modified glassy carbon electrodes, the change in PQQ's redox potential was estimated to be approximately 67 mV pH −1 , with the highest reversible reduction-oxidation observed at ∼pH 2. The nature of the modified electrode surface can also affect P...

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“…The resulting PQQ–CNTs were purified by centrifugation at 14,000 rpm and washing with DMF and water. The immobilization number of PQQ on the surface of CNT-NH 2 was calculated by measuring the adsorption intensity change of PQQ at 330 nm with a standard curve method ( Figure S1 ) [ 34 ]. The immobilization capability of CNT-NH 2 to PQQ was estimated to be 287 ± 26 nmol/mg.…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Immunosensors with PQQ-Decorated Carbon Nanotubes as Signal Labels for Electrocatalytic Oxidation of Tris(2-carboxyethyl)phosphine

Deng

Xia

et al. 2021

Nanomaterials

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Nanocatalysts are a promising alternative to natural enzymes as the signal labels of electrochemical biosensors. However, the surface modification of nanocatalysts and sensor electrodes with recognition elements and blockers may form a barrier to direct electron transfer, thus limiting the application of nanocatalysts in electrochemical immunoassays. Electron mediators can accelerate the electron transfer between nanocatalysts and electrodes. Nevertheless, it is hard to simultaneously achieve fast electron exchange between nanocatalysts and redox mediators as well as substrates. This work presents a scheme for the design of electrochemical immunosensors with nanocatalysts as signal labels, in which pyrroloquinoline quinone (PQQ) is the redox-active center of the nanocatalyst. PQQ was decorated on the surface of carbon nanotubes to catalyze the electrochemical oxidation of tris(2-carboxyethyl)phosphine (TCEP) with ferrocenylmethanol (FcM) as the electron mediator. With prostate-specific antigen (PSA) as the model analyte, the detection limit of the sandwich-type immunosensor was found to be 5 pg/mL. The keys to success for this scheme are the slow chemical reaction between TCEP and ferricinum ions, and the high turnover frequency between ferricinum ions, PQQ. and TCEP. This work should be valuable for designing of novel nanolabels and nanocatalytic schemes for electrochemical biosensors.

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Pyrroloquinoline quinone maintains redox activity when bound to a DNA aptamer

Abstract: Newly identified DNA aptamers for PQQ provide an environment in which PQQ is still accessible for redox chemistry.

Cited by 10 publications

References 44 publications

Identification of lactate dehydrogenase as a mammalian pyrroloquinoline quinone (PQQ)-binding protein

Identification of lactate dehydrogenase as a mammalian pyrroloquinoline quinone (PQQ)-binding protein

Electrochemistry of Pyrroloquinoline Quinone (PQQ) on Multi-Walled Carbon Nanotube-Modified Glassy Carbon Electrodes in Biological Buffers

Electrochemical Immunosensors with PQQ-Decorated Carbon Nanotubes as Signal Labels for Electrocatalytic Oxidation of Tris(2-carboxyethyl)phosphine

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