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Delgado-García E, Piedras P, Gómez-Baena G, García-Magdaleno IM, Pineda M, Gálvez-Valdivieso G. Nucleoside Metabolism Is Induced in Common Bean During Early Seedling Development. FRONTIERS IN PLANT SCIENCE 2021; 12:651015. [PMID: 33841480 PMCID: PMC8027947 DOI: 10.3389/fpls.2021.651015] [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: 01/21/2021] [Accepted: 03/05/2021] [Indexed: 06/12/2023]
Abstract
Nucleoside hydrolases (NSH; nucleosidases) catalyze the cleavage of nucleosides into ribose and free nucleobases. These enzymes have been postulated as key elements controlling the ratio between nucleotide salvage and degradation. Moreover, they play a pivotal role in ureidic legumes by providing the substrate for the synthesis of ureides. Furthermore, nucleotide metabolism has a crucial role during germination and early seedling development, since the developing seedlings require high amount of nucleotide simultaneously to the mobilization of nutrient in cotyledons. In this study, we have cloned two nucleosidases genes from Phaseolus vulgaris, PvNSH1 and PvNSH2, expressed them as recombinant proteins, and characterized their catalytic activities. Both enzymes showed a broad range of substrate affinity; however, PvNSH1 exhibited the highest activity with uridine, followed by xanthosine, whereas PvNSH2 hydrolyses preferentially xanthosine and shows low activity with uridine. The study of the regulation of nucleosidases during germination and early postgerminative development indicated that nucleosidases are induced in cotyledons and embryonic axes just after the radicle emergence, coincident with the induction of nucleases activity and the synthesis of ureides in the embryonic axes, with no remarkable differences in the level of expression of both nucleosidase genes. In addition, nucleosides and nucleobase levels were determined as well in cotyledons and embryonic axes. Our results suggest that PvNSH1 and PvNSH2 play an important role in the mobilization of nutrients during this crucial stage of plant development.
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Affiliation(s)
- Elena Delgado-García
- Departamento de Botánica, Ecología y Fisiología Vegetal. Grupo de Fisiología Molecular y Biotecnología de Plantas. Campus de Excelencia Internacional en Agroalimentación, Campus de Rabanales, Edif. Severo Ochoa, Universidad de Córdoba, Córdoba, Spain
| | - Pedro Piedras
- Departamento de Botánica, Ecología y Fisiología Vegetal. Grupo de Fisiología Molecular y Biotecnología de Plantas. Campus de Excelencia Internacional en Agroalimentación, Campus de Rabanales, Edif. Severo Ochoa, Universidad de Córdoba, Córdoba, Spain
| | - Guadalupe Gómez-Baena
- Departamento de Bioquímica y Biología Molecular, Campus de Excelencia Internacional en Agroalimentación, Campus de Rabanales, Edif. Severo Ochoa, Universidad de Córdoba, Córdoba, Spain
| | - Isabel M. García-Magdaleno
- Servicio Central de Apoyo a la Investigación (SCAI), Unidad de Espectrometría de Masas y Cromatografía, Campus de Rabanales, Universidad de Córdoba, Córdoba, Spain
| | - Manuel Pineda
- Departamento de Botánica, Ecología y Fisiología Vegetal. Grupo de Fisiología Molecular y Biotecnología de Plantas. Campus de Excelencia Internacional en Agroalimentación, Campus de Rabanales, Edif. Severo Ochoa, Universidad de Córdoba, Córdoba, Spain
| | - Gregorio Gálvez-Valdivieso
- Departamento de Botánica, Ecología y Fisiología Vegetal. Grupo de Fisiología Molecular y Biotecnología de Plantas. Campus de Excelencia Internacional en Agroalimentación, Campus de Rabanales, Edif. Severo Ochoa, Universidad de Córdoba, Córdoba, Spain
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Ashihara H, Stasolla C, Fujimura T, Crozier A. Purine salvage in plants. PHYTOCHEMISTRY 2018; 147:89-124. [PMID: 29306799 DOI: 10.1016/j.phytochem.2017.12.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 12/10/2017] [Accepted: 12/14/2017] [Indexed: 05/04/2023]
Abstract
Purine bases and nucleosides are produced by turnover of nucleotides and nucleic acids as well as from some cellular metabolic pathways. Adenosine released from the S-adenosyl-L-methionine cycle is linked to many methyltransferase reactions, such as the biosynthesis of caffeine and glycine betaine. Adenine is produced by the methionine cycles, which is related to other biosynthesis pathways, such those for the production of ethylene, nicotianamine and polyamines. These purine compounds are recycled for nucleotide biosynthesis by so-called "salvage pathways". However, the salvage pathways are not merely supplementary routes for nucleotide biosynthesis, but have essential functions in many plant processes. In plants, the major salvage enzymes are adenine phosphoribosyltransferase (EC 2.4.2.7) and adenosine kinase (EC 2.7.1.20). AMP produced by these enzymes is converted to ATP and utilised as an energy source as well as for nucleic acid synthesis. Hypoxanthine, guanine, inosine and guanosine are salvaged to IMP and GMP by hypoxanthine/guanine phosphoribosyltransferase (EC 2.4.2.8) and inosine/guanosine kinase (EC 2.7.1.73). In contrast to de novo purine nucleotide biosynthesis, synthesis by the salvage pathways is extremely favourable, energetically, for cells. In addition, operation of the salvage pathway reduces the intracellular levels of purine bases and nucleosides which inhibit other metabolic reactions. The purine salvage enzymes also catalyse the respective formation of cytokinin ribotides, from cytokinin bases, and cytokinin ribosides. Since cytokinin bases are the active form of cytokinin hormones, these enzymes act to maintain homeostasis of cellular cytokinin bioactivity. This article summarises current knowledge of purine salvage pathways and their possible function in plants and purine salvage activities associated with various physiological phenomena are reviewed.
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Affiliation(s)
- Hiroshi Ashihara
- Department of Biology, Ochanomizu University, Bunkyo-ku, Tokyo, 112-8610, Japan.
| | - Claudio Stasolla
- Department of Plant Science, University of Manitoba, Winnipeg, R3T 2N2, Canada
| | - Tatsuhito Fujimura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan
| | - Alan Crozier
- Department of Nutrition, University of California, Davis, CA, 95616-5270, USA
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Stasolla C, Loukanina N, Ashihara H, Yeung EC, Thorpe TA. Changes of purine and pyrimidine nucleotide biosynthesis during shoot initiation from epicotyl explants of white spruce (Picea glauca). PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2006; 171:345-354. [PMID: 22980203 DOI: 10.1016/j.plantsci.2006.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 04/05/2006] [Accepted: 04/10/2006] [Indexed: 06/01/2023]
Abstract
Nucleotide metabolism was investigated during white spruce organogenesis by following the metabolic fate of (14)C-labeled adenine, adenosine and inosine, as purine precursors, and orotic acid, uridine, and uracil, as pyrimidine intermediates. Key enzymes of purine and pyrimidine metabolism were also assayed during the organogenic process. White spruce epicotyl explants cultured on shoot-forming (SF) medium had a better ability to utilize adenine and adenosine for nucleotide and nucleic acid synthesis, compared to tissue cultured on non-shoot forming (NSF) medium. High levels of salvage products were observed in SF tissue after 10 days in culture, when shoot formation was initiated along the epicotyl axis of the explants. Such a differential utilization of purine precursors was mainly due to the higher specific activity of the two adenine and adenosine salvage enzymes, adenine phosphoribosyltransferase (APRT) and adenosine kinase (AK), measured in SF tissue. Similar catabolism of inosine was observed in both SF and NSF conditions during the 30 days of culture. For pyrimidines, the higher activities of the de novo, salvage, and degradation pathways observed in SF tissue, compared to NSF tissue throughout the course of the experiment, clearly denote a faster turnover of pyrimidine nucleotides in the former. Taken together, these results suggest that a better utilization of purine bases and nucleosides for nucleotide and nucleic acid synthesis, as well as a more rapid turnover of pyrimidine nucleotides, represent a physiological switch, which occurs during the initiation and continuation of the organogenic process in white spruce.
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Affiliation(s)
- Claudio Stasolla
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
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Szuwart M, Starzyńska E, Pietrowska-Borek M, Guranowski A. Calcium-stimulated guanosine--inosine nucleosidase from yellow lupin (Lupinus luteus). PHYTOCHEMISTRY 2006; 67:1476-85. [PMID: 16820181 DOI: 10.1016/j.phytochem.2006.05.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 05/15/2006] [Accepted: 05/15/2006] [Indexed: 05/10/2023]
Abstract
Guanosine-inosine-preferring nucleoside N-ribohydrolase has been purified to homogeneity from yellow lupin (Lupinus luteus) seeds by ammonium sulfate fractionation, ion-exchange chromatography and gel filtration. The enzyme functions as a monomeric, 80kDa polypeptide, most effectively between pH 4.7 and 5.5. Of various mono- and divalent cations tested, Ca(2+) appeared to stimulate enzyme activity. The nucleosidase was activated 6-fold by 2mM exogenous CaCl(2) or Ca(NO(3))(2), with K(a)=0.5mM (estimated for CaCl(2)). The K(m) values estimated for guanosine and inosine were 2.7+/-0.3 microM. Guanosine was hydrolyzed 12% faster than inosine while adenosine and xanthosine were poor substrates. 2'-Deoxyguanosine, 2'-deoxyinosine, 2'-methylguanosine, pyrimidine nucleosides and 5'-GMP were not hydrolyzed. However, the enzyme efficiently liberated the corresponding bases from synthetic nucleosides, such as 1-methylguanosine, 7-methylguanosine, 1-N(2)-ethenoguanosine and 1-N(2)-isopropenoguanosine, but hydrolyzed poorly the ribosides of 6-methylaminopurine and 2,6-diaminopurine. MnCl(2) or ZnCl(2) inhibited the hydrolysis of guanosine with I(50) approximately 60 microM. Whereas 2'-deoxyguanosine, 2'-methylguanosine, adenosine, as well as guanine were competitive inhibitors of this reaction (K(i) values were 1.5, 3.6, 21 and 9.7 microM, respectively), hypoxanthine was a weaker inhibitor (K(i)=64 microM). Adenine, ribose, 2-deoxyribose, 5'-GMP and pyrimidine nucleosides did not inhibit the enzyme. The guanosine-inosine hydrolase activity occurred in all parts of lupin seedlings and in cotyledons it increased up to 5-fold during seed germination, reaching maximum in the third/fourth day. The lupin nucleosidase has been compared with other nucleosidases.
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Affiliation(s)
- Maciej Szuwart
- Department of Biochemistry and Biotechnology, Agricultural University, 35 Wołyńska Street, 60-637 Poznań, Poland
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Campos A, Rijo-Johansen MJ, Carneiro MF, Fevereiro P. Purification and characterisation of adenosine nucleosidase from Coffea arabica young leaves. PHYTOCHEMISTRY 2005; 66:147-151. [PMID: 15652571 DOI: 10.1016/j.phytochem.2004.11.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 11/09/2004] [Indexed: 05/24/2023]
Abstract
An adenosine nucleosidase (ANase) (EC 3.2.2.7) was purified from young leaves of Coffea arabica L. cv. Catimor. A sequence of fractionating steps was used starting with ammonium sulphate salting-out, followed by anion exchange, hydrophobic interaction and gel filtration chromatography. The enzyme was purified 5804-fold and a specific activity of 8333 nkat mg-1 protein was measured. The native enzyme is a homodimer with an apparent molecular weight of 72 kDa estimated by gel filtration and each monomer has a molecular weight of 34.6 kDa, estimated by SDS-PAGE. The enzyme showed maximum activity at pH 6.0 in citrate-phosphate buffer (50 mM). The calculated Km is 6.3 microM and Vmax 9.8 nKat.
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Affiliation(s)
- Alexandre Campos
- Lab Biotechnologia de Celulas Vegetais, ITQB - Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av Republica, Apt. 127, 2781 - 901 Oeiras, Portugal
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Stasolla C, Katahira R, Thorpe TA, Ashihara H. Purine and pyrimidine nucleotide metabolism in higher plants. JOURNAL OF PLANT PHYSIOLOGY 2003; 160:1271-95. [PMID: 14658380 DOI: 10.1078/0176-1617-01169] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Purine and pyrimidine nucleotides participate in many biochemical processes in plants. They are building blocks for nucleic acid synthesis, an energy source, precursors for the synthesis of primary products, such as sucrose, polysaccharides, phospholipids, as well as secondary products. Therefore, biosynthesis and metabolism of nucleotides are of fundamental importance in the growth and development of plants. Nucleotides are synthesized both from amino acids and other small molecules via de novo pathways, and from preformed nucleobases and nucleosides by salvage pathways. In this article the biosynthesis, interconversion and degradation of purine and pyrimidine nucleotides in higher plants are reviewed. This description is followed by an examination of physiological aspects of nucleotide metabolism in various areas of growth and organized development in plants, including embryo maturation and germination, in vitro organogenesis, storage organ development and sprouting, leaf senescence, and cultured plant cells. The effects of environmental factors on nucleotide metabolism are also described. This review ends with a brief discussion of molecular studies on nucleotide synthesis and metabolism.
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Affiliation(s)
- Claudio Stasolla
- Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
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Li J, Wang D. Cloning and in vitro expression of the cDNA encoding a putative nucleoside transporter from Arabidopsis thaliana. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2000; 157:23-32. [PMID: 10940466 DOI: 10.1016/s0168-9452(00)00261-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nucleoside transporters are integral membrane proteins involved in the uptake or release of nucleosides. Their function constitutes an essential step of the salvage pathway of nucleotide synthesis. In order to study the function of these proteins in higher plants, we cloned the cDNA corresponding to the AtENT1 gene that encodes a putative nucleoside transporter in Arabidopsis thaliana by RT-PCR. The amino acid sequence of the AtENT1 protein deduced from the cloned cDNA shared similarity to those of eukaryotic equilibrative nucleoside transporters. Structure prediction indicated that the deduced AtENT1 protein might possess eleven putative transmembrane domains. Southern hybridization revealed that AtENT1 had one homologue in the Arabidopsis genome. Northern blot analysis showed that AtENT1 might be constitutively expressed in most Arabidopsis organs and in plants at different developmental stages. Two AtENT1 fusion genes, AtENT1-His-tag and GFP-AtENT1-His-tag, were expressed in insect cells. Confocal microscopy demonstrated that the GFP-AtENT1-His-tag fusion protein was targeted specifically to the plasma membrane of insect cells.
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Affiliation(s)
- J Li
- The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics, The Chinese Academy of Sciences, 100101, Beijing, PR China
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Henderson DM, Hanson S, Allen T, Wilson K, Coulter-Karis DE, Greenberg ML, Hershfield MS, Ullman B. Cloning of the gene encoding Leishmania donovani S-adenosylhomocysteine hydrolase, a potential target for antiparasitic chemotherapy. Mol Biochem Parasitol 1992; 53:169-83. [PMID: 1501636 DOI: 10.1016/0166-6851(92)90019-g] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A full-length gene encoding the S-adenosylhomocysteine hydrolase (AdoHcyase) enzyme has been isolated from a genomic library of Leishmania donovani DNA in lambda GEM-11 by cross-hybridization to the full-length human AdoHcyase cDNA. The nucleotide sequence of the SalI fragment contained a single open reading frame that encoded a polypeptide of 438 amino acids (47,712 Da). After maximum gap alignment, the predicted amino acid sequence of the leishmanial AdoHcyase was 70-73% identical to AdoHCyases from higher eukaryotes. In addition, a data base search revealed that the primary structure of all AdoHcyase proteins was highly homologous to that of a protein encoded by a mRNA from Drosophila melanogaster that maps near the r element function of the Abd-b homeotic gene. In Northern blots, the SalI fragment hybridized to a 3.0-kb transcript that presumably encodes the parasite enzyme. Southern blot analysis of genomic DNA revealed that the AdoHcyase gene did not exist as a tandemly repeated array within the L. donovani genome. Moreover, monoclonal antibodies generated against human AdoHcyase recognized a leishmanial protein on immunoblots. Finally, the growth of L. donovani promastigotes could be arrested by micromolar concentrations of 3-deazaaristeromycin (C3Ari) and 9-(trans-2',trans-3'-dihydroxycyclopentanyl)adenine, 2 known inhibitors of mammalian AdoHcyase. C3Ari also induced a substantial expansion of the intracellular pools of both AdoHcy and S-adenosylmethionine (AdoMet), as well as a significant diminution of the AdoMet/AdoHcy ratio. Thus, AdoHcyase may have therapeutic potential for the selective treatment of diseases of parasitic origin.
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Affiliation(s)
- D M Henderson
- Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, Portland 97201-3098
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Guranowski A, Starzyńska E, Rataj-Guranowska M, Günther Sillero MA. Purification of apyrase from yellow lupin cotyledons after extraction with perchloric acid. Protein Expr Purif 1991; 2:235-9. [PMID: 1668272 DOI: 10.1016/1046-5928(91)90078-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Neutralized 1 M perchloric acid (PCA) extracts of yellow lupin (Lupinus luteus) seedling cotyledons contain considerable amounts of apyrase (EC 3.6.1.5). Investigators who use PCA extraction for the estimation of nucleotide levels, particularly in plant tissues, should be aware of this danger. Only when the material is treated with 1.8-2 M PCA are the extracts obtained free of apyrase activity. Chromatography of neutralized 1 M extracts obtained from 7-day-old seedling cotyledons on DEAE-Sephacel and Sephadex G-100 yields almost homogeneous apyrase that shows a band of M(r) 51,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels. The molecular weight of the native enzyme is also about 51,000. The apyrase preparation is free of nonspecific phosphatases, nucleotidases, and adenosine nucleosidase, as well as dinucleoside polyphosphate-degrading enzymes. The apyrase exhibits a broad pH optimum between 6 and 8. Mg2+ and Ca2+ are required for maximum activity; Zn2+ and Mn2+ are less effective and Co2+, Ni2+, and Cd2+ are without effect. The Km values for ATP and ADP are about 20 microM. All common 5'-nucleoside tri- and diphosphates as well as adenosine 5'-tetraphosphate are substrates.
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Affiliation(s)
- A Guranowski
- Katedra Biochemii, Akademia Rolnicza, Poznań, Poland
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Gomi T, Takata Y, Fujioka M. Rat liver S-adenosylhomocysteinase. Spectrophotometric study of coenzyme binding. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 994:172-9. [PMID: 2910349 DOI: 10.1016/0167-4838(89)90157-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: 01/03/2023]
Abstract
Rat liver S-adenosylhomocysteinase, a homotetramer, was resolved by treatment with acid ammonium sulfate into apoenzyme and NAD. The apoenzyme thus prepared retained a tetrameric structure but differed in the mobility on nondenaturing polyacrylamide gel electrophoresis. The inactive apoenzyme was reactivated upon incubation with NAD. The restoration of activity paralleled with the tight binding of NAD to apoenzyme, and full activity was obtained when 4 mol of NAD were bound per mol of apoenzyme. The kinetics of reconstitution were apparently biphasic and suggest the existence of two conformers in a slow equilibrium, one of which binds the coenzyme rapidly while the other does so very slowly, if at all. In addition to NAD, apoadenosylhomocysteinase tightly bound nicotinamide hypoxanthine dinucleotide, 3-acetylpyridine adenine dinucleotide and nicotinic acid-adenine dinucleotide. NADP was not bound. Catalytic activity was found only with the enzyme reconstituted with NAD or nicotinamide hypoxanthine dinucleotide. The spectral change observed on interaction of apoadenosylhomocysteinase with NAD was similar to those seen with adenine nucleotides, and was largely approximated by the addition of dioxane to aqueous solutions of adenine nucleotides. By comparison of the difference spectra, it is suggested that the adenine portion of the coenzyme is bound in the hydrophobic pocket of the protein, and that the binding is accompanied by perturbation of tryptophan residue of the protein.
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Affiliation(s)
- T Gomi
- Department of Biochemistry, Toyama Medical and Pharmaceutical University Faculty of Medicine, Japan
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Kasir J, Aksamit RR, Backlund PS, Cantoni GL. Amino acid sequence of S-adenosyl-L-homocysteine hydrolase from Dictyostelium discoideum as deduced from the cDNA sequence. Biochem Biophys Res Commun 1988; 153:359-64. [PMID: 3288206 DOI: 10.1016/s0006-291x(88)81231-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
S-Adenosyl-L-homocysteine hydrolase has been cloned from a lambda gt11 cDNA library prepared from Dictyostelium discoideum that had been starved for 3 hours. The sequence of the cloned cDNA was determined and the deduced amino acid sequence was compared to the amino acid sequence of rat AdoHcy hydrolase. When the sequences from the two species were aligned, 74% of the amino acids were in identical positions. If conservative changes were taken into account the homology was 84%. Because differences have been reported in the binding characteristics of NAD+ to the D. discoideum and rat AdoHcy hydrolases, changes in the amino acids of the putative NAD+-binding site were of particular interest. Six changes were observed in this region but the changes appeared to be in regions that are not critical to the three dimensional folding of the NAD+-binding site.
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Affiliation(s)
- J Kasir
- Laboratory of General and Comparative Biochemistry, National Institute of Mental Health, Bethesda, MD 20892
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Guranowski AB, Chiang PK, Cantoni GL. 5'-Methylthioadenosine nucleosidase. Purification and characterization of the enzyme from Lupinus luteus seeds. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 114:293-9. [PMID: 6783408 DOI: 10.1111/j.1432-1033.1981.tb05148.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
5'-Methylthioadenosine nucleosidase (EC 3.2.2.9), the enzyme which catalyzes hydrolytic cleavage of 5'-methylthioadenosine with the formation of adenine and 5'-methylthioribose, has been purified to homogeneity from Lupinus luteus seeds. The nucleosidase has a native molecular weight of 62 000 and consists of two identical subunits, as judged by gel filtration and dodecylsulfate/polyacrylamide gel electrophoresis. The nucleosidase exhibits highest specificity towards the natural substrate with a Km of 4.1 X 10(-7) M for 5'-methylthioadenosine. It does not cleave adenine from S-adenosylhomocysteine. Among the synthetic analogs of 5'-methylthioadenosine tested, eleven compounds appear to be able to substitute as substrates. Furthermore, the enzyme can liberate hypoxanthinine from six inosyl (deaminated) derivatives obtained by enzymatic deamination of 5'-methylthioadenosine and its synthetic analogs. The Km for 5'-methylthioinosine is 55 microM, and the maximal velocity about 50-times lower than for 5'-methylthioadenosine. The reaction catalyzed by the nucleosidase can be inhibited by adenine (Ki = 11 microM), 3-deazaadenine (Ki = 19 microM), and 9-erythro(2-hydroxyl-3-nonyl)adenine (ki = 37 microM).
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Schneider Z. A micromethod for estimation of adenosine deaminase and adenosine nucleosidase with modified cellulose nitrate membranes. Anal Biochem 1980; 108:104-11. [PMID: 7457848 DOI: 10.1016/0003-2697(80)90698-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Guranowski A. Plant adenosine kinase: purification and some properties of the enzyme from Lupinus luteus seeds. Arch Biochem Biophys 1979; 196:220-6. [PMID: 41481 DOI: 10.1016/0003-9861(79)90569-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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