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Pyrroloquinoline Quinone (pyrroloquinoline + quinone)
Selected AbstractsEnhanced rat sciatic nerve regeneration through silicon tubes filled with pyrroloquinoline quinoneMICROSURGERY, Issue 4 2005Shiqing Liu M.D. Pyrroloquinoline quinone (PQQ) is an antioxidant that also stimulates nerve growth factor (NGF) synthesis and secretion. In an earlier pilot study in our laboratory, Schwann cell growth was accelerated, and NGF mRNA expression and NGF secretion were promoted. The present study was designed to explore the possible nerve-inducing effect of PQQ on a nerve tube model over a 1-cm segmental deficit. An 8-mm sciatic nerve deficit was created in a rat model and bridged by a 1-cm silicone tube. Then,10 ,l of 0.03 mmol/l PQQ were perfused into the silicone chamber in the PQQ group. The same volume of normal saline was delivered in the control group. Each animal underwent functional observation (SFI) at 2-week intervals and electrophysiological studies at 4-week intervals for 12 weeks. Histological and morphometrical analyses were performed at the end of the experiment, 12 weeks after tube implantation. Using a digital image-analysis system, thickness of the myelin sheath was measured, and total numbers of regenerated axons were counted. There was a significant difference in SFI, electrophysiological index (motor-nerve conduct velocity and amplitude of activity potential), and morphometrical results (regenerated axon number and thickness of myelin sheath) in nerve regeneration between the PQQ group and controls (P < 0.05). More mature, high-density, newly regenerated nerve was observed in the PQQ group. We conclude that PQQ is a potent enhancer for the regeneration of peripheral nerves. © 2005 Wiley-Liss, Inc. Microsurgery 25:329,337, 2005. [source] Pyrroloquinoline quinone-dependent carbohydrate dehydrogenase: Activity enhancement and the role of artificial electron acceptorsBIOTECHNOLOGY JOURNAL, Issue 8 2010Juozas Kulys Professor Abstract Pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase (PQQ-GDH) offers a variety of opportunities for applications, e.g. in highly sensitive biosensors and electrosynthetic reactions. Here we report on the acceleration (up to 4.9 x 104 -fold) of enzymatic ferricyanide reduction by artificial redox mediators (enhancers). The reaction mechanism includes reduction of the PQQ-GDH by glucose followed by oxidation of the reduced PQQ cofactor with either ferricyanide or a redox mediator. A synergistic effect occurs through the oxidation of a reduced mediator by ferricyanide. Using kinetic description of the coupled reaction, the second order rate constant for the reaction of an oxidized mediator with the reduced enzyme cofactor (kox) can be calculated. For different mediators this value is 2.2 x 106,1.6 x 108 M -1s -1 at pH 7.2 and 25°C. However, no correlation of the rate constant with the midpoint redox potential of the mediator could be established. For low-potential mediators the synergistic effect is proportional to the ratio of kox(med)/kox(ferricyanide), whereas for the high-potential mediators the effect depends on both this ratio and the concentration of the oxidized mediator, which can be calculated from the Nernst equation. The described effect can be applied in various ways, e.g. for substrate reactivity determination, electrosynthetic PQQ cofactor regeneration or building of new highly sensitive biosensors. [source] Behavior of PQQ Glucose Dehydrogenase on Prussian Blue-Modified Carbon ElectrodeELECTROANALYSIS, Issue 13 2008Valdas Laurinavicius Abstract Glucose sensitive biosensor containing pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase immobilized on Prussian blue (PB)-modified graphite electrode was designed. Properties of the biosensor were investigated in the cathodic and anodic response detection regions. It was shown, that anodic response of the biosensor is sum of two signals: direct electron transport from reduced PQQ to the electrode and by formation of the PQQ-oxygen-PB-carbon ternary complex. Cathodic response of the biosensor is based on the oxidation of the reduced PQQ by PB-oxygen-PB complex. Electrochemical regeneration of the enzyme does not produce free hydrogen peroxide. [source] Inactivation of pqq genes of Enterobacter intermedium 60-2G reduces antifungal activity and induction of systemic resistanceFEMS MICROBIOLOGY LETTERS, Issue 1 2008Song Hee Han Abstract Enterobacter intermedium 60-2G, a phosphate solubilizing bacterium, has the ability to induce systemic resistance in plants against soft rot pathogen Erwinia carotovora. Glucose dehydrogenase, an enzyme that utilizes pyrroloquinoline quinone (PQQ) as a cofactor, is required for the synthesis of gluconic acid by E. intermedium 60-2G. Here, we report that the pqqA and pqqB genes are required for phosphate solubilization and induced systemic resistance against a soft rot pathogen in tobacco. Mutations in either the pqqA or pqqB gene abolished the production of 2-ketogluconic acid and eliminated the ability of E. intermedium to solubilize hydroxyapatite. Addition of gluconic acid to the growth media restored the ability of the pqqA mutant to produce 2-ketogluconic acid. Interestingly, both pqqA and pqqB mutants of E. intermedium lost their ability to inhibit the growth of the rice pathogen Magnaporthe grisea KI-409. Additionally, induced systemic resistance against the soft rot pathogen was attenuated in the pqq mutants. These functions were restored by complementation with the wild-type pqq gene cluster. Our findings suggest that PQQ plays an important function in beneficial traits including phosphate solubilization, antifungal activity, and induced systemic resistance of E. intermedium, possibly by acting as a cofactor for several enzymes including glucose dehydrogenase. [source] Direct hydride transfer in the reaction mechanism of quinoprotein alcohol dehydrogenases: a quantum mechanical investigationJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2001A. Jongejan Abstract Oxidation of alcohols by direct hydride transfer to the pyrroloquinoline quinone (PQQ) cofactor of quinoprotein alcohol dehydrogenases has been studied using ab initio quantum mechanical methods. Energies and geometries were calculated at the 6-31G(d,p) level of theory. Comparison of the results obtained for PQQ and several derivatives with available structural and spectroscopic data served to judge the feasibility of the calculations. The role of calcium in the enzymatic reaction mechanism has been investigated. Transition state searches have been conducted at the semiempirical and STO-3G(d) level of theory. It is concluded that hydride transfer from the C,-position of the substrate alcohol (or aldehyde) directly to the C(5) carbon of PQQ is energetically feasible. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1732,1749, 2001 [source] Enhanced rat sciatic nerve regeneration through silicon tubes filled with pyrroloquinoline quinoneMICROSURGERY, Issue 4 2005Shiqing Liu M.D. Pyrroloquinoline quinone (PQQ) is an antioxidant that also stimulates nerve growth factor (NGF) synthesis and secretion. In an earlier pilot study in our laboratory, Schwann cell growth was accelerated, and NGF mRNA expression and NGF secretion were promoted. The present study was designed to explore the possible nerve-inducing effect of PQQ on a nerve tube model over a 1-cm segmental deficit. An 8-mm sciatic nerve deficit was created in a rat model and bridged by a 1-cm silicone tube. Then,10 ,l of 0.03 mmol/l PQQ were perfused into the silicone chamber in the PQQ group. The same volume of normal saline was delivered in the control group. Each animal underwent functional observation (SFI) at 2-week intervals and electrophysiological studies at 4-week intervals for 12 weeks. Histological and morphometrical analyses were performed at the end of the experiment, 12 weeks after tube implantation. Using a digital image-analysis system, thickness of the myelin sheath was measured, and total numbers of regenerated axons were counted. There was a significant difference in SFI, electrophysiological index (motor-nerve conduct velocity and amplitude of activity potential), and morphometrical results (regenerated axon number and thickness of myelin sheath) in nerve regeneration between the PQQ group and controls (P < 0.05). More mature, high-density, newly regenerated nerve was observed in the PQQ group. We conclude that PQQ is a potent enhancer for the regeneration of peripheral nerves. © 2005 Wiley-Liss, Inc. Microsurgery 25:329,337, 2005. [source] Microstructural and tensile properties of elastin-based polypeptides crosslinked with Genipin and pyrroloquinoline quinoneBIOPOLYMERS, Issue 3 2007S. Vieth Abstract Elastin is an elastomeric, self-assembling extracellular matrix protein with potential for use in biomaterials applications. Here, we compare the microstructural and tensile properties of the elastin-based recombinant polypeptide (EP) EP20-244 crosslinked with either genipin (GP) or pyrroloquinoline quinone (PQQ). Recombinant EP-based sheets were produced via coacervation and subsequent crosslinking. The micron-scale topography of the GP-crosslinked sheets examined with atomic force microscopy revealed the presence of extensive mottling compared with that of the PQQ-crosslinked sheets, which were comparatively smoother. Confocal microscopy showed that the subsurface porosity in the GP-crosslinked sheets was much more open. GP-crosslinked EP-based sheets exhibited significantly greater tensile strength (P , 0.05). Mechanistically, GP appears to yield a higher crosslink density than PQQ, likely due to its capacity to form short-range and long-range crosslinks. In conclusion, GP is able to strongly modulate the microstructural and mechanical properties of elastin-based polypeptide biomaterials forming membranes with mechanical properties similar to native insoluble elastin. © 2006 Wiley Periodicals, Inc. Biopolymers 85: 199,206, 2007. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | |||||||||||||