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PubMed1995

Three distinct quinoprotein alcohol dehydrogenases are expressed when Pseudomonas putida is grown on different alcohols.

A bacterial strain that can utilize several kinds of alcohols as its sole carbon and energy sources was isolated from soil and tentatively identified as Pseudomonas putida HK5. Three distinct dye-linked alcohol dehydrogenases (ADHs), each of which contained the prosthetic group pyrroloquinoline quinone (PQQ), were formed in the soluble fractions of this strain grown on different alcohols. ADH I was formed most abundantly in the cells grown on ethanol and was similar to the quinoprotein ADH reported for P. putida (H. Görisch and M. Rupp, Antonie Leeuwenhoek 56:35-45, 1989) except for its isoelectric point. The other two ADHs, ADH IIB and ADH IIG, were formed separately in the cells grown on 1-butanol and 1,2-propanediol, respectively. Both of these enzymes contained heme c in addition to PQQ and functioned as quinohemoprotein dehydrogenases. Potassium ferricyanide was an available electron acceptor for ADHs IIB and IIG but not for ADH I. The molecular weights were estimated to be 69,000 for ADH IIB and 72,000 for ADH IIG, and both enzymes were shown to be monomers. Antibodies raised against each of the purified ADHs could distinguish the ADHs from one another. Immunoblot analysis showed that ADH I was detected in cells grown on each alcohol tested, but ethanol was the most effective inducer. ADH IIB was formed in the cells grown on alcohols of medium chain length and also on 1,3-butanediol. Induction of ADH IIG was restricted to 1,2-propanediol or glycerol, of which the former alcohol was more effective. These results from immunoblot analysis correlated well with the substrate specificities of the respective enzymes. Thus, three distinct quinoprotein ADHs were shown to be synthesized by a single bacterium under different growth conditions.

1-Butanol↗
PubMed1996

Pyrroloquinoline quinone, a chemotactic attractant for Escherichia coli.

Escherichia coli is attracted by pyrroloquinoline quinone (PQQ), and chemotaxis toward glucose is enhanced by the presence of PQQ. A ptsI mutant showed no chemotactic response to either glucose or PQQ alone but did show a chemotactic response to a mixture of glucose and PQQ. A strain lacking the methylated chemotaxis receptor protein Tar showed no response to PQQ.

Bacterial Proteins↗
PubMed1996

Characterization and nucleotide sequence of pqqE and pqqF in Methylobacterium extorquens AM1.

Methylobacterium extorquens AM1 pqqEF are genes required for synthesis of pyrroloquinoline quinone (PQQ). The nucleotide sequence of these genes indicates PqqE belongs to an endopeptidase family, including PqqF of Klebsiella pneumoniae, and M. extorquens AM1 PqqF has low identity with the same endopeptidase family. M. extorquens AM1 pqqE complemented a K. pneumoniae pqqF mutant.

Amino Acid Sequence↗
PubMed1997

Cloning and expression of a gene cluster encoding three subunits of membrane-bound gluconate dehydrogenase from Erwinia cypripedii ATCC 29267 in Escherichia coli.

We have cloned the gene cluster encoding three subunits of membrane-bound gluconate dehydrogenase (GADH) from Erwinia cypripedii ATCC 29267 in Escherichia coli by performing a direct-expression assay. The positive clone converted D-gluconate to 2-keto-D-gluconate (2KDG) in the culture medium. Nucleotide sequence analysis of the GADH clone revealed that the cloned fragment contained the complete structural genes for a 68-kDa dehydrogenase subunit, a 47-kDa cytochrome c subunit, and a 24-kDa subunit of unknown function and that the genes were clustered with the same transcriptional polarity. Comparison of the deduced amino acid sequences and the NH2-terminal sequences determined for the purified protein indicated that the dehydrogenase, cytochrome c, and 24-kDa subunits contained typical signal peptides of 22, 19, and 42 amino acids, respectively. The molecular masses of the processed subunits deduced from the nucleotide sequences (65, 45, and 20 kDa) coincided well with the molecular masses of subunits estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In E. cypripedii and recombinant E. coli, the GADH was constitutively formed and the activity of GADH was enhanced more than twofold by addition of D-gluconate to the medium. The holoenzyme glucose dehydrogenase of E. coli was reconstituted by addition of pyrroloquinoline quinone to the culture medium, and the conversion of D-glucose or D-gluconate to 2KDG by recombinant E. coli harboring the cloned GADH gene was attempted in batch culture. The conversion yields for D-glucose were 0.95 mol of 2KDG/mol of D-glucose after 16 h of cultivation, and those for D-gluconate were 0.95 mol of 2KDG/mol of D-gluconate after 12 h of cultivation.

Amino Acid Sequence↗
PubMed1988

Quinone derivatives lower blood and liver acetaldehyde but not ethanol concentrations following ethanol loading to rats.

A rise in blood and liver acetaldehyde concentrations following an intragastric administration of ethanol to rats was significantly inhibited when the quinone derivatives 2,3-dimethoxy-5-methyl-6-decaprenyl-1,4-benzoquinone (ubidecarenone, coenzyme Q10), 4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid (pyrroloquinoline quinone, PQQ) and 6-(10-hydroxydecyl)-2,3-dimethoxy-5-methyl-1,4-benzoquinone (idebenone) were injected intraperitoneally, prior to ethanol load, at a dose of 10, 11.5 and 30 mg/kg of body weight, respectively. When acetaldehyde was incubated in vitro with 1,4-benzoquinone (3.7-13.0 mM) or PQQ (1.4-4.9 mM) at 0 and 40 degrees C, the acetaldehyde concentrations slowly decreased with incubation time at 40 degrees C. The results suggest that low acetaldehyde concentrations following ethanol load are due to an accelerated oxidation of acetaldehyde by PQQ in the liver and the circulating blood.

Acetaldehyde↗
PubMed2006

Comparison of pyrroloquinoline quinone and/or metoprolol on myocardial infarct size and mitochondrial damage in a rat model of ischemia/reperfusion injury.

The cardioprotective effectiveness of low-dose pyrroloquinoline quinone (PQQ, 3 mg/kg) was compared with metoprolol, a beta(1)-selective adrenoceptor antagonist. Rats underwent 30 minutes of left anterior descending coronary artery occlusion and 2 hours of reperfusion. Metoprolol and/or PQQ were given at the onset of reperfusion to mimic clinical treatment. Metoprolol and/or PQQ reduced infarct size and protected against ischemia-induced left ventricular dysfunction after 2 hours of reperfusion. Combined therapy augmented left ventricular developed pressure at the end of reperfusion. Metoprolol or PQQ alone enhanced mitochondrial respiratory ratios in ischemic and nonischemic myocardium. Although the PQQ/metoprolol combination therapy increased respiratory ratio values, the effects were small when compared with PQQ alone. Only PQQ decreased lipid peroxidation. Metoprolol and/or PQQ given at the onset of reperfusion reduce infarct size and improve cardiac function. Combination therapy further reduces infarct size. PQQ is superior to metoprolol in protecting mitochondria from ischemia/reperfusion oxidative damage.

Adrenergic beta-Antagonists↗
PubMed2003

Pyrroloquinoline quinone improves growth and reproductive performance in mice fed chemically defined diets.

Growth, reproductive performance, and indices of collagen maturation and expression were investigated in Balb/c mice fed chemically defined, amino acid-based diets with or without the addition 6 micro Mpyrroloquinoline quinone (PQQ)/kg diet. The diets were fed to virgin mice for 8 weeks before breeding. At weaning, the pups from successful pregnancies were fed the same diet as their respective dams. Reproductive performance was compromised in mice fed diets devoid of PQQ, and their offspring grew at slower rates than offspring from mice fed diets supplemented with PQQ. Successful mating (confirmed vaginal plugs) was not affected by the presence or absence of PQQ; however, pup viability (number of pups at parturition/number of pups at Day 4 of lactation) was decreased in PQQ-deprived mice. Conception (percentage of females giving live births) and fertility (percentage of births) were also decreased in PQQ-deprived mice. The slower rates of growth in offspring from PQQ-deprived mice were associated with decreased steady-state mRNA levels for Type I procollagen alpha(1)-chains in skin and lungs from neonatal mice. Values for lysyl oxidase accumulation as protein in PQQ-deficient mice also tended to be lower than corresponding values from PQQ-supplemented or -replete mice. Skin collagen solubility was increased in PQQ-deprived mice. These results indicate that PQQ supplementation can improve reproductive performance, growth, and may modulate indices of neonatal extracellular matrix production and maturation in mice fed chemically defined, but otherwise nutritionally complete diets.

Animals↗
PubMed1996

Synthesis and aldose reductase-inhibitory activity of imidazopyrroloquinoline esters.

Derivatives of imidazopyrroloquinoline (IPQ) and its esters were synthesized. Some of these compounds potently inhibited aldose reductases of rabbit lens and dog kidney, as well as the human recombinant enzyme, though the coenzyme pyrroloquinoline quinone (PQQ) was a relatively poor inhibitor. The IPQ esters with a methyl substituent at the C-3 carboxyl group were less potent inhibitors than the analogs without esterification at this position. An IPQ ester with the free carboxyl group at C-3 inhibited sorbitol accumulation in rat red blood cells.

Aldehyde Reductase↗
PubMed1996

Cyclooxygenase induction is essential for NGF synthesis enhancement by NGF inducers in L-M cells.

Nerve growth factor (NGF) inducers, for example, 4-methylcatechol, pyrroloquinoline quinone, kansuinin A, and ingenol triacetate, stimulate NGF synthesis in L-M cells, but the mechanism of NGF induction by NGF inducers is not known. Using the four different types of previously described NGF inducers, we proved induction of cyclooxygenase activity by NGF inducers and detected prostaglandins D2 and E2 as metabolites of arachidonic acid. From the observation that the induction of NGF by each NGF inducers was inhibited by cyclooxygenase inhibitors or dexamethasone, cyclooxygenase activation is supposed to be an essential process for NGF induction.

Animals↗
PubMed2002

Molecular cloning and functional expression of D-sorbitol dehydrogenase from Gluconobacter suboxydans IF03255, which requires pyrroloquinoline quinone and hydrophobic protein SldB for activity development in E. coli.

The sldA gene that encodes the D-sorbitol dehydrogenase (SLDH) from Gluconobacter suboxydans IFO 3255 was cloned and sequenced. It encodes a polypeptide of 740 residues, which contains a signal sequence of 24 residues. SLDH had 35-37% identity to the membrane-bound quinoprotein glucose dehydrogenases (GDHs) from E. coli, Gluconobacter oxydans, and Acinetobacter calcoaceticus except the N-terminal hydrophobic region of GDH. Additionally, the sldB gene located just upstream of sldA was found to encode a polypeptide consisting of 126 very hydrophobic residues that is similar in sequence to the one-sixth N-terminal region of the GDH. For the development of the SLDH activity in E. coli, co-expression of the sldA and sldB genes and the presence of pyrrloquinolone quinone as a co-factor were required.

Amino Acid Sequence↗
PubMed2002

L-erythrulose production by oxidative fermentation is catalyzed by PQQ-containing membrane-bound dehydrogenase.

Thermotolerant Gluconobacter frateurii CHM 43 was selected for L-erythrulose production from mesoerythritol at higher temperatures. Growing cells and the membrane fraction of the strain rapidly oxidized mesoerythritol to L-erythrulose irreversibly with almost 100% of recovery at 37 degrees C. L-Erythrulose was also produced efficiently by the resting cells at 37 degrees C with 85% recovery. The enzyme responsible for mesoerythritol oxidation was found to be located in the cytoplasmic membrane of the organism. The EDTA-resolved enzyme required PQQ and Ca2+ for L-erythrulose formation, suggesting that the enzyme catalyzing meso-erythritol oxidation was a quinoprotein. Quinoprotein membrane-bound mesoerythritol dehydrogenase (QMEDH) was solubilized and purified to homogeneity. The purified enzyme showed a single band in SDS-PAGE of which the molecular mass corresponded to 80 kDa. The optimum pH of QMEDH was found at pH 5.0. The Michaelis constant of the enzyme was found to be 25 mM for meso-erythritol as the substrate. QMEDH showed a broad substrate specificity toward C3-C6 sugar alcohols in which the erythro form of two hydroxy groups existed adjacent to a primary alcohol group. On the other hand, the cytosolic NAD-denpendent meso-erythritol dehydrogenase (CMEDH) of the same organism was purified to a crystalline state. CMEDH showed a molecular mass of 60 kDa composed of two identical subunits, and an apparent sedimentation constant was 3.6 s. CMEDH catalyzed oxidoreduction between mesoerythritol and L-erythrulose. The oxidation reaction was observed to be reversible in the presence of NAD at alkaline pHs such as 9.0-10.5. L-Erythrulose reduction was found at pH 6.0 with NADH as coenzyme. Judging from the catalytic properties, the NAD-dependent enzyme in the cytosolic fraction was regarded as a typical pentitol dehydrogenase of NAD-dependent and the enzyme was independent of the oxidative fermentation of L-erythrulose production.

Catalysis↗
PubMed1994

Aspects of the release of superoxide by leukocytes, and a means by which this is switched off.

Although great progress has been made in understanding the respiratory burst of leukocytes that produce superoxide (O2-), it is possible that a component or components, might have been overlooked. Furthermore, O2- production and its sequels, though cardinal in bactericidal action, might ultimately be damaging to the host's own cells. It is important, therefore, that a biologic mechanism exist to turn off O2- production by stimulated leukocytes. This article offers evidence that methoxatin (PQQ), a redox-cycling orthoquinone, might be involved in O2- production by leukocytes. This is based on the fact that inhibitors of O2- production, such as diphenylene iodonium (DPI) and 4,5-dimethylphenylene diamine (DIMPDA), were shown to sequester PQQ in leukocytes, i.e., to form adducts with that substance. Addition of PQQ to cells blocked with the inhibitors partially restored O2- release. With respect to turning off cellular O2- release, a factor was observed to be released to the medium by old macrophages (14 days old, but not by those less than 7 days old). Such conditioned medium, when added to stimulated neutrophils or macrophages, blocked O2- release. This factor was sensitive to proteases, exhibited molecular sizes of 3 and 11 kDa, and its action was independent of the nature of the stimulus applied to the leukocytes. It was partially purified by column (sizing) chromatography and HPLC. It seems to be a general modulator of the release of reactive oxygen species by phagocytes and is irrespective of phagocytic cellular type, or species from which the cells were derived.

Chromatography, High Pressure Liquid↗
PubMed2005

Electrochemical determination of thiols at single-wall carbon nanotubes and PQQ modified electrodes.

The electrocatalytic oxidation of thiols has been observed at a glassy carbon (GC) electrode coated with a single-wall carbon nanotube (SWNT) film. Fourteen thiols including L-cysteine (CySH) and glutathione were tested using the SWNT/GC electrode, and the cyclic voltammetry (CV) showed that each thiol was oxidized at much less positive potential than those at other electrodes such as bare GC and diamond electrodes. The SWNT/GC electrode was also modified with pyrroloquinoline quinone (PQQ) which showed a further improvement of the catalytic behavior of the SWNT/GC electrode: e.g. the oxidation peak current of CySH was observed at 0.27 V vs. Ag/AgCl in pH 7.5 phosphate buffer. The amperometic responses at these electrodes showed a linear relationship with the substrate concentration in a 10(-6)-10(-3) M range and 10(-6)-10(-7) M detection limits for several thiols including CySH, L-homocysteine, N-acetyl-L-cysteine, L-penicillamine and glutathione. These electrodes show a response time of 2-3 s and storage stabilities over 3 weeks. A PQQ/SWNT/GC electrode has been successfully applied for the assay of both L-cysteine and N-acetyl-L-cysteine in the dietary supplement.

Cysteine↗
PubMed1989

Methoxatin (PQQ), coenzyme for copper-dependent amine and mixed-function oxidation in mammalian tissues.

The newly discovered coenzyme PQQ can now be measured at picomole levels with redox cycling methods developed in our laboratory. PQQ-peptides have been obtained from digests of the copper quinoenzymes, diamine oxidase, lysyl oxidase and dopamine-beta-hydroxylase. PQQ is present in egg yolk and milk, suggesting its immediate availability for developing embryos and newborn animals. We suggest that PQQ, when exposed in traumatized, ischemic, inflammed or pathological tissues, may catalyze the formation of large amounts of superoxide and should be considered as a source of oxidative stress when planning pharmacotherapeutic intervention. PQQ and quinoproteins play a role in the redox metabolism and structural integrity of cells and tissues.

Amines↗
PubMed1989

Effects of the yeast extract components pyrroloquinoline quinone and aspartic acid on vitamin B12 production in Klebsiella pneumoniae IFO 13541.

The production of vitamin B12 from carbohydrates, peptone, casamino acid, etc., by intestinal bacteria was investigated. Klebsiella pneumoniae IFO 13541 was the most efficient strain for vitamin B12 production, which depended exclusively on the concentration of yeast extract added to the medium. A concentrated solution of yeast extract (1 ml) was chromatographed on a Sephadex G-25 column (1 x 180 cm) and eluted with H2O (eighty fractions of 3 ml each were collected). It was found that fractions in which bacterial growth was most prevalent also exhibited the highest amount of vitamin production. The effectiveness of yeast extract was shown by the participation of pyrroloquinoline quinone and aspartic acid in the growth stimulation and in the vitamin B12 production in this strain.

Acetobacter↗
PubMed1993

Participation of aspartic acid and pyrroloquinoline quinone in vitamin B12 production in Klebsiella pneumoniae IFO 13541.

Vitamin B12 production by Gram-negative facultative anaerobic intestinal bacteria, members of the family Enterobacteriaceae, was examined. Klebsiella pneumoniae IFO 13541 was the most effective strain with regard to such production. The growth of the strain and its production of vitamin B12 depended exclusively on the concentration of yeast extract added to the medium. The yeast extract components required for the stimulation of bacterial growth and or vitamin B12 production were identified as aspartic acid and pyrroloquinoline quinone (PQQ) and the relationship between vitamin B12 production and these two components was examined. The metabolism of aspartic acid in this process was also investigated; the major metabolites were alanine, glutaminic acid, and valine. The formation of alanine depended on dehydrogenase, the activity of which was greatly increased with increasing PQQ concentration.

Alanine↗