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Ke C, Ren Y, Gao P, Han J, Tao Y, Huang J, Yang X. Separation and purification of pyrroloquinoline quinone from fermentation broth by pretreatment coupled with macroporous resin adsorption. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.117962] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yamada Y, Nishii K, Kuwata K, Nakamichi M, Nakanishi K, Sugimoto A, Ikemoto K. Effects of pyrroloquinoline quinone and imidazole pyrroloquinoline on biological activities and neural functions. Heliyon 2020; 6:e03240. [PMID: 32021931 PMCID: PMC6994848 DOI: 10.1016/j.heliyon.2020.e03240] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 06/03/2019] [Accepted: 01/13/2020] [Indexed: 12/12/2022] Open
Abstract
Pyrroloquinoline quinone (PQQ) is contained in fruits and vegetables and in human breast milk. It has been reported that PQQ has high reactivity and changes to an imidazole structure (imidazole pyrroloquinoline) by a reaction with an amino acid at a high ratio in nature. A comparative study was conducted to clarify physiological effects including neuroprotective effects, growth-promoting effect, antioxidative effects and a stimulatory effect on mitochondriogensis of PQQ and imidazole pyrroloquinoline (IPQ) using a human neuroblastoma cell line and a hepatocellular carcinoma cell line. We also compared the expression levels of human cytochrome c oxidase subunit IV isoform Ⅰ (COX4/1), which is an index of the amount of mitochondria in the cells that had been exposed to PQQ, PQQH2 and IPQ. The results of the comparison showed that IPQ had almost the same biological activities as those of PQQ except for anti-oxidative activity. It was also shown that PQQ and IPQ improve the memory learning ability of aged mice and that BioPQQ® improves brain function in the language field in humans.
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Affiliation(s)
- Yasue Yamada
- Department of Biotechnology and Chemistry, Faculty of Engineering, Kindai University, Higashi-Hiroshima, Hiroshima, 739-2116, Japan
| | - Kazuya Nishii
- Department of Biotechnology and Chemistry, Faculty of Engineering, Kindai University, Higashi-Hiroshima, Hiroshima, 739-2116, Japan
| | - Koji Kuwata
- Department of Biotechnology and Chemistry, Faculty of Engineering, Kindai University, Higashi-Hiroshima, Hiroshima, 739-2116, Japan
| | - Masashi Nakamichi
- Department of Biotechnology and Chemistry, Faculty of Engineering, Kindai University, Higashi-Hiroshima, Hiroshima, 739-2116, Japan
| | - Kei Nakanishi
- Department of Biotechnology and Chemistry, Faculty of Engineering, Kindai University, Higashi-Hiroshima, Hiroshima, 739-2116, Japan
| | - Atsushi Sugimoto
- Niigata Research Laboratory, Mitsubishi Gas Chemical Company, Inc., Niigata, 950-3112, Japan
| | - Kazuto Ikemoto
- Niigata Research Laboratory, Mitsubishi Gas Chemical Company, Inc., Niigata, 950-3112, Japan
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Kato C, Kawai E, Shimizu N, Mikekado T, Kimura F, Miyazawa T, Nakagawa K. Determination of pyrroloquinoline quinone by enzymatic and LC-MS/MS methods to clarify its levels in foods. PLoS One 2018; 13:e0209700. [PMID: 30576372 PMCID: PMC6303014 DOI: 10.1371/journal.pone.0209700] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 12/09/2018] [Indexed: 11/19/2022] Open
Abstract
Pyrroloquinoline quinone (PQQ) is believed to be a new B vitamin-like compound, and PQQ supplementation has received attention as a possible treatment for diseases including dementia and diabetes. However, the distribution of PQQ in foods is unclear, due to the difficulty in analyzing the compound. Therefore, in this study, enzymatic and LC-MS/MS methods were optimized to enable an accurate analysis of PQQ in foods. The optimized methods were applied to the screening of foods, in which PQQ contents were identified in ng/g or ng/mL levels. Furthermore, we newly found that some foods related to acetic acid bacteria contain PQQ at 1.94~5.59 ng/mL higher than beer, which is known to contain relatively high amounts of PQQ. These results suggest that the optimized methods are effective for the screening of foods containing PQQ. Such foods with high PQQ content may be valuable as functional foods effective towards the treatment of certain diseases.
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Affiliation(s)
- Chikara Kato
- Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Emiko Kawai
- Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Naoki Shimizu
- Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Tsuyoshi Mikekado
- Niigata Research Laboratory, Mitsubishi Gas Chemical Company, Inc., Niigata, Japan
| | - Fumiko Kimura
- Department of Human Health and Nutrition, Shokei Gakuin University, Natori, Japan
| | - Teruo Miyazawa
- New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai, Japan
- Food and Health Science Research Unit, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Kiyotaka Nakagawa
- Food and Biodynamic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
- * E-mail:
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Yang L, Rong Z, Zeng M, Cao Y, Gong X, Lin L, Chen Y, Cao W, Zhu L, Dong W. Pyrroloquinoline quinone protects nucleus pulposus cells from hydrogen peroxide-induced apoptosis by inhibiting the mitochondria-mediated pathway. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2014; 24:1702-10. [PMID: 25349108 DOI: 10.1007/s00586-014-3630-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 10/17/2014] [Accepted: 10/17/2014] [Indexed: 11/24/2022]
Abstract
PURPOSE Intervertebral disc cell apoptosis has been suggested to play a key role in promoting disc degeneration, and many studies have shown that the mechanism may be related to oxidative stress. Pyrroloquinoline quinone (PQQ), a redox cofactor for bacterial dehydrogenases, possesses the potential to scavenge reactive oxygen species (ROS) and inhibit cell apoptosis. The objective of this study was to evaluate the effects of PQQ on cultured rat nucleus pulposus (NP) cells under conditions of oxidative injury induced by hydrogen peroxide (H2O2) and to investigate the underlying mechanisms in vitro. METHODS Cell viability was determined by CCK8 assay. Changes in the apoptosis rate, intracellular ROS levels and the mitochondrial membrane potential were measured by flow cytometry. Extracellular matrix (ECM)-related proteins (collagen-2 and aggrecan) and apoptosis-related proteins (Bcl-2, Bax, cytochrome c, and caspase-3) were investigated by western blotting. RESULTS The results show that NP cells pretreated with PQQ before H2O2 exposure exhibited increased cell viability, decreased ROS formation, maintained mitochondrial membrane potential, and reduced apoptosis. In the presence of PQQ, ECM production was maintained by the cells despite being in an apoptotic environment. In addition, pretreatment with PQQ increased the expression of Bcl-2, inhibited the release of mitochondrial cytochrome c, and decreased the expressions of Bax and cleaved caspase-3. CONCLUSIONS Our results suggest that PQQ can protect rat NP cells against oxidative stress via a mitochondria-mediated pathway. PQQ might be useful as a potential pharmaceutical agent in the prevention of intervertebral disc degeneration.
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Affiliation(s)
- Lianjun Yang
- Department of Orthopaedics, Zhu Jiang Hospital, Southern Medical University, No. 253, Gongye Big Road, Guangzhou, 510280, China
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He K, Nukada H, Urakami T, Murphy MP. Antioxidant and pro-oxidant properties of pyrroloquinoline quinone (PQQ): implications for its function in biological systems. Biochem Pharmacol 2003; 65:67-74. [PMID: 12473380 DOI: 10.1016/s0006-2952(02)01453-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pyrroloquinoline quinone (PQQ) is a novel redox cofactor recently found in human milk. It has been reported to function as an essential nutrient, antioxidant and redox modulator in cell culture experiments and in animal models of human diseases. As mitochondria are particularly susceptible to oxidative damage we studied the antioxidant properties of PQQ in isolated rat liver mitochondria. PQQ was an effective antioxidant protecting mitochondria against oxidative stress-induced lipid peroxidation, protein carbonyl formation and inactivation of the mitochondrial respiratory chain. In contrast, PQQ caused extensive cell death to cells in culture. This surprising effect was inhibited by catalase, and was shown to be due to the generation of hydrogen peroxide during the autoxidation of PQQ in culture medium. We conclude that the reactivities of PQQ are dependent on its environment and that it can act as an antioxidant or a pro-oxidant in different biological systems.
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Affiliation(s)
- Kai He
- Department of Medical and Surgical Sciences, Dunedin School of Medicine, University of Otago, P.O. Box 56, Dunedin, New Zealand
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Jongejan A, Machado SS, Jongejan JA. The enantioselectivity of quinohaemoprotein alcohol dehydrogenases: mechanistic and structural aspects. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1381-1177(99)00063-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mitchell AE, Jones AD, Mercer RS, Rucker RB. Characterization of pyrroloquinoline quinone amino acid derivatives by electrospray ionization mass spectrometry and detection in human milk. Anal Biochem 1999; 269:317-25. [PMID: 10222004 DOI: 10.1006/abio.1999.4039] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe a HPLC method coupled to electrospray ionization mass spectrometry (ESI/MS) for quantification and identification of pyrroloquinoline quinone (PQQ) and condensation products formed upon incubation of PQQ with amino acids (IPQ; imidazolopyrroloquinoline and I/OPQ/R; imidazolopyrroloquinoline with attached R-group). More importantly, using these methods we demonstrate the presence of both PQQ and IPQ in human milk in nanomolar to micromolar concentrations. PQQ was incubated with amino acids and condensation products were separated by HPLC. Fractions corresponding to each product were collected and molecular masses were determined using ESI/MS. Ala, Asp, Arg, Cys, Gly, Glu, Ser, Thr, Trp, and Tyr form IPQ upon incubation with PQQ. Yields of IPQ were low (<5%) for Asp and Glu, yet high (>60%) for Thr. In addition to IPQ, Ala, Arg, Cys, Ser, Trp, and Tyr formed IPQ/R derivatives. His, Ile, Leu, Glu, Leu, Lys, Met, and Phe form only IPQ/R derivatives. Proline did not react with PQQ. Mass spectra indicate that PQQ forms stable hydrated carbonyls and decarboxylates easily. Although mass spectra were complicated by the oxidation state of the quinone and decarboxylation of PQQ, these methods are invaluable for the rapid detection of the full range of PQQ adducts in biological matrices.
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Affiliation(s)
- A E Mitchell
- Department of Nutrition, University of California, Davis, California 95616-8669, USA
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McIntire WS. Newly discovered redox cofactors: possible nutritional, medical, and pharmacological relevance to higher animals. Annu Rev Nutr 1998; 18:145-77. [PMID: 9706222 DOI: 10.1146/annurev.nutr.18.1.145] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Research spurred by the discovery of pyrroloquinoline quinone (PPQ) in 1979 led to the discovery of four additional oxidation-reduction (redox) cofactors, all of which result from transmogrification of amino acyl side chains in respective enzymes. These cofactors are (a) topa quinone in copper-containing amine oxidases, enzymes found in nearly all forms of life, including human; (b) lysyl topa quinone of the copper protein lysyl oxidase, an enzyme required for proper cross-linking of collagen and elastin; (c) tryptophan tryptophylquinone of alkylamine dehydrogenases from gram-negative soil bacteria; and (d) the copper-complexed cysteinyltyrosyl radical of fungal galactose oxidase. Originally, PQQ was thought to be a covalently bound cofactor in numerous enzymes from eukaryotes and prokaryotes. Today, PQQ is only found as a noncovalent cofactor in bacterial enzymes. The ubiquity of PQQ in the environment and its steady accessibility in the human diet has raised questions concerning its role as a vitamin, or an essential or helpful nutrient. The relevance to nutrition, medicine, and pharmacology of PQQ, topa quinone, lysyl topa quinone, tryptophan trytophylquinone, the galactose oxidase cofactor, and the enzymes harboring these cofactors are discussed in this review.
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Affiliation(s)
- W S McIntire
- Department of Veterans Affairs Medical Center, San Francisco, California 94121, USA.
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Affiliation(s)
- H Narita
- Department of Food Science, Kyoto Women's University, Japan
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10
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Misset-Smits M, Oltshoorn AJ, Dewanti A, Duine JA. Production, assay, and occurrence of pyrroloquinoline quinone. Methods Enzymol 1997; 280:89-98. [PMID: 9211309 DOI: 10.1016/s0076-6879(97)80105-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- M Misset-Smits
- Department of Microbiology and Enzymology, Delft University of Technology, The Netherlands
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Esaka Y, Yamaguchi Y, Kano K, Goto M. Separation of amino acid-oxazole derivatives of the redox coenzyme pyrroloquinoline quinone by capillary zone electrophoresis. J Chromatogr A 1993; 652:225-32. [PMID: 8281258 DOI: 10.1016/0021-9673(93)80663-s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Condensation products (oxazole derivatives) from the reaction of the coenzyme pyrroloquinoline quinone (PQQ) with several alpha-amino acids were successfully separated by capillary zone electrophoresis. Addition of a certain organic solvent such as dimethyl sulphoxide to the electrolyte solution is essential for reproducible and complete separation. The organic modifier appears to prevent the oxazole derivatives from absorbing on the capillary wall. Product analysis of the condensation reactions of PQQ with amino acids was performed by this method and the mechanism is discussed briefly. PQQ-spiked bovine serum was also analysed. Unsubstituted type 1 oxazole derivative was predominantly detected. This result suggests that most of the PQQ in mammalian fluids, if any, exists as PQQ derivatives, probably as a type 1 oxazole derivative.
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Affiliation(s)
- Y Esaka
- Gifu Pharmaceutical University, Japan
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Naito Y, Kumazawa T, Kino I, Suzuki O. Effects of pyrroloquinoline quinone (PQQ) and PQQ-oxazole on DNA synthesis of cultured human fibroblasts. Life Sci 1993; 52:1909-15. [PMID: 8389410 DOI: 10.1016/0024-3205(93)90631-c] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effects of pyrroloquinoline quinone (PQQ) and PQQ-oxazole (PQQ-glycine adduct) on DNA synthesis were examined using cultured human fibroblasts. Confluent fibroblasts were cultured in serum-free Dulbecco's modified Eagle's media, and various concentrations of PQQ and PQQ-oxazole were added to the media. After incubation for 24 h, [3H]thymidine was added to the media as an indicator for DNA synthesis of the cells. The thymidine incorporation into the cells was significantly enhanced even in the presence of very low concentrations of PQQ (0.003-0.03 microM); it remained significantly enhanced, up to 30 microM PQQ. However, the incorporation remarkably decreased at 750-1500 microM of PQQ. In contrast to the results for PQQ, DNA synthesis was not stimulated by addition of 0.003-3 microM PQQ-oxazole, but it was slightly enhanced at concentrations 15-750 microM. In morphological examination of the cultured human fibroblasts, cell density was increased by addition of 0.003-30 microM PQQ when compared with that of the control, supporting the above biochemical data. However, there were no distinct differences in morphological effect between PQQ and PQQ-oxazole.
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Affiliation(s)
- Y Naito
- Department of Pathology, Hamamatsu University School of Medicine, Japan
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Buffoni F, Cambi S, Moneti G. Pyrroloquinoline quinone, a method for its isolation and identification by mass spectrometry. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1116:297-304. [PMID: 1319209 DOI: 10.1016/0304-4165(92)90043-t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Procedures for the unambiguous detection and for the isolation and mass spectrometric identification of pyrroloquinoline quinone (PQQ) are presented. The procedure involved acid hydrolysis of protein in the presence of phenylhydrazine and successive isolation and identification of the formed adduct using mass spectrometry. In HPLC the phenylhydrazone of PQQ gave many methylated products, of which the predominant compound was the pentamethylated derivative. After reaction of the phenylhydrazone derivative of PQQ (PHPQQ) with ammonia, a product was obtained which did not contain phenylhydrazine and which formed a pentamethylated derivative as the main methylation product. The HPLC profiles of the methylated products of PHPQQ and of its ammonia derivative were very characteristic and could be used for identification in addition to mass spectrometry. However, prolonged treatment of proteins with phenylhydrazine during hydrolysis can result in the formation of a material that resembles PQQ in some aspects of its behaviour. Thus, analysis by MS is essential for unambiguous identification. This analytical procedure was applied to pig plasma benzylamine oxidase, pig aorta lysyl oxidase, pig kidney diamine oxidase and bovine serum albumin with negative results. However, samples of pronase contained variable quantities of non-covalently bound PQQ: this can lead to erroneous identification of PQQ in enzyme after pronase digestion.
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Affiliation(s)
- F Buffoni
- Department of Pharmacology, University of Florence, Italy
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Itoh S, Mure M, Suzuki A, Murao H, Ohshiro Y. Reaction of coenzyme PQQ with amino acids. Oxidative decarboxylation, oxidative dealdolation (Cα–Cβfission) and oxazolopyrroloquinoline (OPQ) formation. ACTA ACUST UNITED AC 1992. [DOI: 10.1039/p29920001245] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Duine JA. Quinoproteins: enzymes containing the quinonoid cofactor pyrroloquinoline quinone, topaquinone or tryptophan-tryptophan quinone. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 200:271-84. [PMID: 1653700 DOI: 10.1111/j.1432-1033.1991.tb16183.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
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. Another group of quinoproteins, consisting of amine oxidoreductases, has a protein chain containing one of the following quinonoid aromatic amino acids: 6-hydroxy-phenylalanine-3,4-dione (TPQ) or 4-(2'-tryptophyl)-tryptophan-6,7-dione (TTQ). There is no doubt that these o-quinones play a role as cofactor, in the case of TPQ in prokaryotic as well as eukaryotic amine oxidases. It appears, therefore, that a novel class of amino-acid-derived cofactors is emerging, ranging from the free radical form of tyrosine and tryptophan to those containing a dicarbonyl group (like the already known pyryvoyl group and the o-quinones here described.
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Affiliation(s)
- J A Duine
- Department of Microbiology and Enzymology, Delft University of Technology, The Netherlands
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Voltammetric and spectroscopic properties of the ammonia adduct of pyrroloquinoline quinone. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0022-0728(90)80061-a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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van der Meer RA, Groen BW, Jongejan JA, Duine JA. The redox-cycling assay is not suited for the detection of pyrroloquinoline quinone in biological samples. FEBS Lett 1990; 261:131-4. [PMID: 2155129 DOI: 10.1016/0014-5793(90)80653-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Based on the results of the so-called redox-cycling assay it has been claimed that various common foods and beverages as well as mammalian body fluids and tissues contain substantial quantities (microM) of free PQQ [M. Paz et al. (1989) in: PQQ and Quinoproteins (J.A. Jongejan and J.A. Duine, eds.) Kluwer Academic Publishers, Dordrecht, pp. 131-143 and J. Killgore et al. (1989) Science 245, 850-852]. However, by investigating samples from such sources with a biological assay of nM sensitivity, we could not confirm these claims. Analysis of the samples with procedures that proved adequate for the detection of PQQ adducts and conjugates gave equally negative results. To account for the positive response in the redox-cycling assay, as opposed to the negative results obtained by other methods, a search was made for those substances in these samples that caused the false-positive reactions. It was found that a number of commonly occurring biochemicals like ascorbic and dehydroascorbic acid, riboflavin and to a lesser extent pyridoxal phosphate, gave a positive response in the redox-cycling assay. The amounts of these interfering substances that were determined in the samples by independent methods could well explain the response. In separate experiments it was found that the effect of PQQ added to biological samples was obscured over an appreciable range of concentrations. For these reasons it must be concluded that the redox-cycling assay is not suited for the detection of PQQ in these samples. Any claims that are based on the results of this method should be disregarded.
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Affiliation(s)
- R A van der Meer
- Department of Microbiology and Enzymology, Delft Universaity of Technology, The Netherlands
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Mure M, Suzuki A, Itoh S, Ohshiro Y. Oxidative Cα–Cβfission (dealdolation) of β-hydroxy amino acids by coenzyme PQQ. ACTA ACUST UNITED AC 1990. [DOI: 10.1039/c39900001608] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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van der Meer RA, Groen BW, van Kleef MA, Frank J, Jongejan JA, Duine JA. Isolation, preparation, and assay of pyrroloquinoline quinone. Methods Enzymol 1990; 188:260-83. [PMID: 2177820 DOI: 10.1016/0076-6879(90)88043-a] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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