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Liepman AH, Jaworski M, Ramirez-Lopez C. Spectrophotometric Assays for Measuring Hydroxypyruvate Reductase Activity. Methods Mol Biol 2024; 2792:77-81. [PMID: 38861079 DOI: 10.1007/978-1-0716-3802-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Hydroxypyruvate reductase (HPR; EC 1.1.1.81) activity is integral to the photorespiratory pathway. Within photorespiration, HPR catalyzes the reduction of hydroxypyruvate, a product of the serine:glyoxylate aminotransferase reaction to glycerate, a substrate for glycerate kinase, using NADH as cofactor. Here we detail a spectrophotometric assay for measuring HPR activity in vitro by following the consumption of NADH at 340 nm.
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Affiliation(s)
- Aaron H Liepman
- Biology Department, Eastern Michigan University, Ypsilanti, MI, USA.
| | - Mara Jaworski
- Biology Department, Eastern Michigan University, Ypsilanti, MI, USA
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Miyazawa SI, Ujino-Ihara T, Miyama T, Tahara K, Tobita H, Suzuki Y, Nishiguchi M. Different photorespiratory mechanisms in conifer leaves, where peroxisomes have intrinsically low catalase activity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:1004-1020. [PMID: 37162489 DOI: 10.1111/tpj.16276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 04/28/2023] [Accepted: 05/03/2023] [Indexed: 05/11/2023]
Abstract
Photorespiration is an essential metabolic mechanism associated with photosynthesis; however, little is known about the photorespiratory pathway of conifer gymnosperms. Metabolite analyses of the leaves of 27 tree species showed that the mean glycerate content in conifer leaves was lower than that in angiosperm leaves. We performed experiments where [13 C]-serine was fed to detached shoots of a conifer (Cryptomeria japonica), via the transpiration stream, and compared the labeling patterns of photorespiratory metabolites with those of an angiosperm tree (Populus nigra), because glycerate is produced from serine via hydroxypyruvate in peroxisomes. In P. nigra, hydroxypyruvate, glycerate and glycine were labeled with 13 C, whereas in C. japonica, glycolate and a non-canonical photorespiratory metabolite, formate, were also labeled, suggesting that an H2 O2 -mediated non-enzymatic decarboxylation (NED) reaction occurs in C. japonica. We analyzed changes in the metabolite contents of leaves kept in the dark and leaves exposed to illuminated photorespiration-promoting conditions: a positive relationship between formate and serine levels in C. japonica implied that the active C1 -metabolism pathway synthesizes serine from formate. Leaf gas exchange analyses revealed that CO2 produced through NED was recaptured by chloroplasts. Database analysis of the peroxisomal targeting signal motifs of an H2 O2 -scavenging enzyme, catalase, derived from various species, including nine coniferous species, as well as analyses of peroxisomal fractions isolated from C. japonica and P. nigra leaves indicated that conifer peroxisomes had less catalase activity. These results suggest that NED and the subsequent C1 metabolism are involved in the photorespiratory pathway of conifer leaves, where peroxisomes have intrinsically low catalase activity.
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Affiliation(s)
- Shin-Ichi Miyazawa
- Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Japan
| | - Tokuko Ujino-Ihara
- Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Japan
| | - Takafumi Miyama
- Department of Disaster Prevention, Meteorology and Hydrology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Japan
| | - Ko Tahara
- Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Japan
| | - Hiroyuki Tobita
- Department of Plant Ecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Japan
| | - Yuji Suzuki
- Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, Japan
| | - Mitsuru Nishiguchi
- Department of Forest Molecular Genetics and Biotechnology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Japan
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Suzuki S, Tanaka D, Miyagi A, Takahara K, Kono M, Noguchi K, Ishikawa T, Nagano M, Yamaguchi M, Kawai-Yamada M. Loss of peroxisomal NAD kinase 3 (NADK3) affects photorespiration metabolism in Arabidopsis. JOURNAL OF PLANT PHYSIOLOGY 2023; 283:153950. [PMID: 36889102 DOI: 10.1016/j.jplph.2023.153950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/22/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Nicotinamide adenine dinucleotides (NAD+ and NADP+) are electron mediators involved in various metabolic pathways. NADP(H) are produced by NAD kinase (NADK) through the phosphorylation of NAD(H). The Arabidopsis NADK3 (AtNADK3) is reported to preferentially phosphorylate NADH to NADPH and is localized in the peroxisome. To elucidate the biological function of AtNADK3 in Arabidopsis, we compared metabolites of nadk1, nadk2 and nadk3 Arabidopsis T-DNA inserted mutants. Metabolome analysis revealed that glycine and serine, which are intermediate metabolites of photorespiration, both increased in the nadk3 mutants. Plants grown for 6 weeks under short-day conditions showed increased NAD(H), indicating a decrease in the phosphorylation ratio in the NAD(P)(H) equilibrium. Furthermore, high CO2 (0.15%) treatment induced a decrease in glycine and serine in nadk3 mutants. The nadk3 showed a significant decrease in post-illumination CO2 burst, suggesting that the photorespiratory flux was disrupted in the nadk3 mutant. In addition, an increase in CO2 compensation points and a decrease in CO2 assimilation rate were observed in the nadk3 mutants. These results indicate that the lack of AtNADK3 causes a disruption in the intracellular metabolism, such as in amino acid synthesis and photorespiration.
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Affiliation(s)
- Shota Suzuki
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama-city, Saitama, 338-8570, Japan
| | - Daimu Tanaka
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama-city, Saitama, 338-8570, Japan
| | - Atsuko Miyagi
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama-city, Saitama, 338-8570, Japan; Faculty of Agriculture, Yamagata University, 1-23 Wakaba-machi, Tsuruoka, Yamagata, 997-8555, Japan
| | - Kentaro Takahara
- Institute of Molecular and Cellular Biosciences, the University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Masaru Kono
- Graduate School of Science, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Ko Noguchi
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Toshiki Ishikawa
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama-city, Saitama, 338-8570, Japan
| | - Minoru Nagano
- College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Masatoshi Yamaguchi
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama-city, Saitama, 338-8570, Japan
| | - Maki Kawai-Yamada
- Graduate School of Science and Engineering, Saitama University, 225 Shimo-Okubo, Sakura-ku, Saitama-city, Saitama, 338-8570, Japan.
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Shi M, Ge T, Wang Y, Zhao L. Photorespiration is essential for acclimation to salt stress under high carbon availability in Chlamydomonas. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Shi M, Zhao L, Wang Y. Identification and Characterization of Genes Encoding the Hydroxypyruvate Reductases in Chlamydomonas Reveal Their Distinct Roles in Photorespiration. FRONTIERS IN PLANT SCIENCE 2021; 12:690296. [PMID: 34249060 PMCID: PMC8264790 DOI: 10.3389/fpls.2021.690296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/31/2021] [Indexed: 06/13/2023]
Abstract
Photorespiration plays an important role in maintaining normal physiological metabolism in higher plants and other oxygenic organisms, such as algae. The unicellular eukaryotic organism Chlamydomonas is reported to have a photorespiration system different from that in higher plants, and only two out of nine genes encoding photorespiratory enzymes have been experimentally characterized. Hydroxypyruvate reductase (HPR), which is responsible for the conversion of hydroxypyruvate into glycerate, is poorly understood and not yet explored in Chlamydomonas. To identify the candidate genes encoding hydroxypyruvate reductases in Chlamydomonas (CrHPR) and uncover their elusive functions, we performed sequence comparison, enzyme activity measurement, subcellular localization, and analysis of knockout/knockdown strains. Together, we identify five proteins to be good candidates for CrHPRs, all of which are detected with the activity of hydroxypyruvate reductase. CrHPR1, a nicotinamide adenine dinucleotide (NADH)-dependent enzyme in mitochondria, may function as the major component of photorespiration. Its deletion causes severe photorespiratory defects. CrHPR2 takes part in the cytosolic bypass of photorespiration as the compensatory pathway of CrHPR1 for the reduction of hydroxypyruvate. CrHPR4, with NADH as the cofactor, may participate in photorespiration by acting as the chloroplastidial glyoxylate reductase in glycolate-quinone oxidoreductase system. Therefore, the results reveal that CrHPRs are far more complex than previously recognized and provide a greatly expanded knowledge base for studies to understand how CrHPRs perform their functions in photorespiration. These will facilitate both modification of photorespiration and genetic engineering for crop improvement by synthetic biology.
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Affiliation(s)
- Menglin Shi
- College of Life Sciences, Nankai University, Tianjin, China
| | - Lei Zhao
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
- National Center of Technology Innovation for Synthetic Biology, Tianjin, China
| | - Yong Wang
- College of Life Sciences, Nankai University, Tianjin, China
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Kumsab J, Tobe R, Kurihara T, Hirose Y, Omori T, Mihara H. Characterization of a novel class of glyoxylate reductase belonging to the β-hydroxyacid dehydrogenase family in Acetobacter aceti. Biosci Biotechnol Biochem 2020; 84:2303-2310. [PMID: 32729375 DOI: 10.1080/09168451.2020.1797470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Enzymes related to β-hydroxyacid dehydrogenases/3-hydroxyisobutyrate dehydrogenases are ubiquitous, but most of them have not been characterized. An uncharacterized protein with moderate sequence similarities to Gluconobacter oxydans succinic semialdehyde reductase and plant glyoxylate reductases/succinic semialdehyde reductases was found in the genome of Acetobacter aceti JCM20276. The corresponding gene was cloned and expressed in Escherichia coli. The gene product was purified and identified as a glyoxylate reductase that exclusively catalyzed the NAD(P)H-dependent reduction of glyoxylate to glycolate. The strict substrate specificity of this enzyme to glyoxylate, the diverged sequence motifs for its binding sites with cofactors and substrates, and its phylogenetic relationship to homologous enzymes suggested that this enzyme represents a novel class of enzymes in the β-hydroxyacid dehydrogenase family. This study may provide an important clue to clarify the metabolism of glyoxylate in bacteria. Abbreviations: GR: glyoxylate reductase; GRHPR: glyoxylate reductase/hydroxypyruvate reductase; HIBADH: 3-hydroxyisobutyrate dehydrogenase; SSA: succinic semialdehyde; SSAR: succinic semialdehyde reductase.
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Affiliation(s)
- Jakkaphan Kumsab
- College of Life Sciences, Ritsumeikan University , Kusatsu, Japan
| | - Ryuta Tobe
- College of Life Sciences, Ritsumeikan University , Kusatsu, Japan
| | - Tatsuo Kurihara
- Institute for Chemical Research, Kyoto University , Kyoto, Japan
| | - Yuu Hirose
- Department of Applied Chemistry and Life Science, Toyohashi University of Technology , Toyohashi, Japan
| | - Taketo Omori
- Department of Biomedical Engineering, Osaka Institute of Technology , Osaka, Japan
| | - Hisaaki Mihara
- College of Life Sciences, Ritsumeikan University , Kusatsu, Japan
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But SY, Egorova SV, Khmelenina VN, Trotsenko YA. Biochemical Properties and Phylogeny of Hydroxypyruvate Reductases from Methanotrophic Bacteria with Different C 1-Assimilation Pathways. BIOCHEMISTRY (MOSCOW) 2018; 82:1295-1303. [PMID: 29223156 DOI: 10.1134/s0006297917110074] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the aerobic methanotrophic bacteria Methylomicrobium alcaliphilum 20Z, Methylococcus capsulatus Bath, and Methylosinus trichosporium OB3b, the biochemical properties of hydroxypyruvate reductase (Hpr), an indicator enzyme of the serine pathway for assimilation of reduced C1-compounds, were comparatively analyzed. The recombinant Hpr obtained by cloning and heterologous expression of the hpr gene in Escherichia coli catalyzed NAD(P)H-dependent reduction of hydroxypyruvate or glyoxylate, but did not catalyze the reverse reactions of D-glycerate or glycolate oxidation. The absence of the glycerate dehydrogenase activity in the methanotrophic Hpr confirmed a key role of the enzyme in utilization of C1-compounds via the serine cycle. The enzyme from Ms. trichosporium OB3b realizing the serine cycle as a sole assimilation pathway had much higher special activity and affinity in comparison to Hpr from Mm. alcaliphilum 20Z and Mc. capsulatus Bath assimilating carbon predominantly via the ribulose monophosphate (RuMP) cycle. The hpr gene was found as part of gene clusters coding the serine cycle enzymes in all sequenced methanotrophic genomes except the representatives of the Verrucomicrobia phylum. Phylogenetic analyses revealed two types of Hpr: (i) Hpr of methanotrophs belonging to the Gammaproteobacteria class, which use the serine cycle along with the RuMP cycle, as well as of non-methylotrophic bacteria belonging to the Alphaproteobacteria class; (ii) Hpr of methylotrophs from Alpha- and Betaproteobacteria classes that use only the serine cycle and of non-methylotrophic representatives of Betaproteobacteria. The putative role and origin of hydroxypyruvate reductase in methanotrophs are discussed.
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Affiliation(s)
- S Y But
- Skryabin Institute of Biochemistry and Physiology of Microorganisms, Laboratory of Methylotrophy, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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Timm S, Nunes-Nesi A, Pärnik T, Morgenthal K, Wienkoop S, Keerberg O, Weckwerth W, Kleczkowski LA, Fernie AR, Bauwe H. A cytosolic pathway for the conversion of hydroxypyruvate to glycerate during photorespiration in Arabidopsis. THE PLANT CELL 2008; 20:2848-59. [PMID: 18952776 PMCID: PMC2590732 DOI: 10.1105/tpc.108.062265] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 08/28/2008] [Accepted: 10/02/2008] [Indexed: 05/17/2023]
Abstract
Deletion of any of the core enzymes of the photorespiratory cycle, one of the major pathways of plant primary metabolism, results in severe air-sensitivity of the respective mutants. The peroxisomal enzyme hydroxypyruvate reductase (HPR1) represents the only exception to this rule. This indicates the presence of extraperoxisomal reactions of photorespiratory hydroxypyruvate metabolism. We have identified a second hydroxypyruvate reductase, HPR2, and present genetic and biochemical evidence that the enzyme provides a cytosolic bypass to the photorespiratory core cycle in Arabidopsis thaliana. Deletion of HPR2 results in elevated levels of hydroxypyruvate and other metabolites in leaves. Photosynthetic gas exchange is slightly altered, especially under long-day conditions. Otherwise, the mutant closely resembles wild-type plants. The combined deletion of both HPR1 and HPR2, however, results in distinct air-sensitivity and a dramatic reduction in photosynthetic performance. These results suggest that photorespiratory metabolism is not confined to chloroplasts, peroxisomes, and mitochondria but also extends to the cytosol. The extent to which cytosolic reactions contribute to the operation of the photorespiratory cycle in varying natural environments is not yet known, but it might be dynamically regulated by the availability of NADH in the context of peroxisomal redox homeostasis.
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Affiliation(s)
- Stefan Timm
- University of Rostock, BioScience Institute, Plant Physiology Department, D-18051 Rostock, Germany
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9
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Kruse O, Rupprecht J, Mussgnug JH, Dismukes GC, Hankamer B. Photosynthesis: a blueprint for solar energy capture and biohydrogen production technologies. Photochem Photobiol Sci 2005; 4:957-70. [PMID: 16307108 DOI: 10.1039/b506923h] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Solar energy capture, conversion into chemical energy and biopolymers by photoautotrophic organisms, is the basis for almost all life on Earth. A broad range of organisms have developed complex molecular machinery for the efficient conversion of sunlight to chemical energy over the past 3 billion years, which to the present day has not been matched by any man-made technologies. Chlorophyll photochemistry within photosystem II (PSII) drives the water-splitting reaction efficiently at room temperature, in contrast with the thermal dissociation reaction that requires a temperature of ca. 1550 K. The successful elucidation of the high-resolution structure of PSII, and in particular the structure of its Mn(4)Ca cluster provides an invaluable blueprint for designing solar powered biotechnologies for the future. This knowledge, combined with new molecular genetic tools, fully sequenced genomes, and an ever increasing knowledge base of physiological processes of oxygenic phototrophs has inspired scientists from many countries to develop new biotechnological strategies to produce renewable CO(2)-neutral energy from sunlight. This review focuses particularly on the potential of use of cyanobacteria and microalgae for biohydrogen production. Specifically this article reviews the predicted size of the global energy market and the constraints of global warming upon it, before detailing the complex set of biochemical pathways that underlie the photosynthetic process and how they could be modified for improved biohydrogen production.
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Affiliation(s)
- Olaf Kruse
- University of Bielefeld, Department of Biology, 33501 Bielefeld, Germany.
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Gragera RR, Martínez-Rodríguez R, Capilla J, De Miguel E, Gómez de Segura I, Turégano L, Alvarez MI, Toledano A. Localization of glyoxylate dehydrogenase and glyoxylate-complex molecules in the rat prefrontal cortex: enzymohistochemical and immunocytochemical study. J Neurosci Res 2000; 59:561-7. [PMID: 10679796 DOI: 10.1002/(sici)1097-4547(20000215)59:4<561::aid-jnr12>3.0.co;2-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Glyoxylic acid is synthesized and catabolized in cells of vertebrates; several pathways have been described. In previous papers, we have demonstrated the localization in some areas of the rat cerebral cortex both of beta-NAD-dependent glyoxylate dehydrogenase (glyoDH), using an enzymohistochemical method, and of glyoxylate-complex molecules, using immunocytochemical procedures. In this study we have applied these two techniques in various areas of the prefrontal cortex with different histological cytoarchitecture. GlyoDH has been located in most neurons, in some glial cells, and in capillary wall structures in all cortical layers of all areas of the rat prefrontal cortex. Antibodies against glyoxylate-complex molecules showed positive immunoreactivity in scattered neurons, mostly of multipolar or stellate appearance, from layers III, IV, and V in the medial precentral area, but not in cortical areas 24, 25, or 32 of the prefrontal cortex. Immunoreaction was found in the periphery of neuronal perikarya and in some of their processes. These results demonstrate the existence of a particular area-dependent neuronal cortical system, of specific but uncertain function, related to glyoxylic acid and/or glyoxylate compounds. At the electron microscope level, positive reaction was associated with synaptic sites, axonal filaments, glial cells, and several components of the blood-brain barrier. These localizations suggest the involvement of glyoxylate derivatives in synaptic functioning and also in glial cell functions.
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Affiliation(s)
- R R Gragera
- Department of Morphological Sciences and Surgery, Faculty of Medicine, Alcalá de Henares University, Alcalá de Henares, Spain
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Yakup Arica M, Halıcıgil C, Alaeddinoğlu G, Denizli A. Affinity interaction of hydroxypyruvate reductase from Methylophilus spp. with Cibacron blue F3GA-derived poly(HEMA EGDMA) microspheres: partial purification and characterization. Process Biochem 1999. [DOI: 10.1016/s0032-9592(98)00104-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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12
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Martínez-Rodríguez R, Alonso MJ, De Miguel E, Gómez de Segura I, Gómez-Aguado F, Picazo A, Corcuera MT, Alvarez MI, Toledano A. Synaptic immunolocalization of glyoxylate-complex molecules in the striate areas of the rat cerebral cortex: light and electron microscopic studies. J Neurosci Res 1998; 51:268-74. [PMID: 9469580 DOI: 10.1002/(sici)1097-4547(19980115)51:2<268::aid-jnr15>3.0.co;2-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The location of glyoxylate-complex molecules has been investigated in several areas of the rat cerebral cortex using the immunohistochemical peroxidase-antiperoxidase (PAP) method. Antibodies against glyoxylate-complex molecules have been developed in the rabbit after immunization with a glyoxylate-bovine serum albumin conjugate. Observations carried out with the light microscope demonstrated positive immunostaining at the membrane level of scattered neurons located in all cortical areas, mainly in cortical layer IV. The striate areas (17, 18, 18a) had both the greatest number of immunopositive neurons and the most intense ones. At the electron microscopic level, it was observed that in the striate areas an immunopositive reaction was located mainly in the periphery of synaptic vesicles of some nerve endings, and in both pre- and postsynaptic membranes of these synaptic structures. The presence of glyoxylic acid and glyoxylate-complex molecules in such areas leads us to suggest that these substances could play an important role in selected synaptic contacts in which some pyramidal and non-pyramidal neurons are involved.
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Chistoserdova LV, Lidstrom ME. Purification and characterization of hydroxypyruvate reductase from the facultative methylotroph Methylobacterium extorquens AM1. J Bacteriol 1991; 173:7228-32. [PMID: 1657886 PMCID: PMC209229 DOI: 10.1128/jb.173.22.7228-7232.1991] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hydroxypyruvate reductase was purified to homogeneity from the facultative methylotroph Methylobacterium extorquens AM1. It has a molecular mass of about 71 kDa, and it consists of two identical subunits with a molecular mass of about 37 kDa. This enzyme uses both NADH (Km = 0.04 mM) and NADPH (Km = 0.06 mM) as cofactors, uses hydroxypyruvate (Km = 0.1 mM) and glyoxylate (Km = 1.5 mM) as the only substrates for the forward reaction, and carries out the reverse reaction with glycerate (Km = 2.6 mM) only. It was not possible to detect the conversion of glycolate to glyoxylate, a proposed role for this enzyme. Kinetics and inhibitory studies of the enzyme from M. extorquens AM1 suggest that hydroxypyruvate reductase is not a site for regulation of the serine cycle at the level of enzyme activity.
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Affiliation(s)
- L V Chistoserdova
- W.M. Keck Laboratories, California Institute of Technology, Pasadena 91125
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14
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Izumi Y, Yoshida T, Kanzaki H, Toki S, Miyazaki SS, Yamada H. Purification and characterization of hydroxypyruvate reductase from a serine-producing methylotroph, Hyphomicrobium methylovorum GM2. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 190:279-84. [PMID: 2114287 DOI: 10.1111/j.1432-1033.1990.tb15573.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Hydroxypyruvate reductase of a serine-producing methylotroph, Hyphomicrobium methylovorum GM2, was purified to complete homogeneity, crystallized and characterized, the first time for an enzyme from a methylotroph. The enzyme was found to be a dimer composed of identical subunits (38 kDa), the molecular mass of the enzyme being about 70 kDa. The enzyme was stable against heating at 25 degrees C for 10 min at pH values between 5 and 9. Optimal activity was observed at pH 6.8 and around 45 degrees C. The enzyme catalyzed the reduction of hydroxypyruvate with the oxidation of only NADH. Other than hydroxypyruvate, only glyoxylate served as a substrate. The Km values were found to be 0.175 mM for hydroxypyruvate and 10.8 mM for glyoxylate. Taking advantage of the high substrate specificity of this enzyme, a means of enzymatic determination of hydroxypyruvate was established.
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Affiliation(s)
- Y Izumi
- Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, Japan
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