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Tian Y, Wang Y, Liu X, Herburger K, Westh P, Møller MS, Svensson B, Zhong Y, Blennow A. Interfacial enzyme kinetics reveals degradation mechanisms behind resistant starch. Food Hydrocoll 2023. [DOI: 10.1016/j.foodhyd.2023.108621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
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2
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Kari J, Molina GA, Schaller KS, Schiano-di-Cola C, Christensen SJ, Badino SF, Sørensen TH, Røjel NS, Keller MB, Sørensen NR, Kolaczkowski B, Olsen JP, Krogh KBRM, Jensen K, Cavaleiro AM, Peters GHJ, Spodsberg N, Borch K, Westh P. Physical constraints and functional plasticity of cellulases. Nat Commun 2021; 12:3847. [PMID: 34158485 PMCID: PMC8219668 DOI: 10.1038/s41467-021-24075-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 05/17/2021] [Indexed: 11/16/2022] Open
Abstract
Enzyme reactions, both in Nature and technical applications, commonly occur at the interface of immiscible phases. Nevertheless, stringent descriptions of interfacial enzyme catalysis remain sparse, and this is partly due to a shortage of coherent experimental data to guide and assess such work. In this work, we produced and kinetically characterized 83 cellulases, which revealed a conspicuous linear free energy relationship (LFER) between the substrate binding strength and the activation barrier. The scaling occurred despite the investigated enzymes being structurally and mechanistically diverse. We suggest that the scaling reflects basic physical restrictions of the hydrolytic process and that evolutionary selection has condensed cellulase phenotypes near the line. One consequence of the LFER is that the activity of a cellulase can be estimated from its substrate binding strength, irrespectively of structural and mechanistic details, and this appears promising for in silico selection and design within this industrially important group of enzymes.
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Affiliation(s)
- Jeppe Kari
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Gustavo A Molina
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Kay S Schaller
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Corinna Schiano-di-Cola
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Stefan J Christensen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Silke F Badino
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | - Nanna S Røjel
- Department of Science and Environment, Roskilde University, Universitetsvej 1, Roskilde, Denmark
| | - Malene B Keller
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg C, Denmark
| | - Nanna Rolsted Sørensen
- Department of Science and Environment, Roskilde University, Universitetsvej 1, Roskilde, Denmark
| | - Bartlomiej Kolaczkowski
- Department of Science and Environment, Roskilde University, Universitetsvej 1, Roskilde, Denmark
| | | | | | | | | | - Günther H J Peters
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | | | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark.
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3
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Vogel K, Wei R, Pfaff L, Breite D, Al-Fathi H, Ortmann C, Estrela-Lopis I, Venus T, Schulze A, Harms H, Bornscheuer UT, Maskow T. Enzymatic degradation of polyethylene terephthalate nanoplastics analyzed in real time by isothermal titration calorimetry. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 773:145111. [PMID: 33940717 DOI: 10.1016/j.scitotenv.2021.145111] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 01/06/2021] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Plastics are globally used for a variety of benefits. As a consequence of poor recycling or reuse, improperly disposed plastic waste accumulates in terrestrial and aquatic ecosystems to a considerable extent. Large plastic waste items become fragmented to small particles through mechanical and (photo)chemical processes. Particles with sizes ranging from millimeter (microplastics, <5 mm) to nanometer (nanoplastics, NP, <100 nm) are apparently persistent and have adverse effects on ecosystems and human health. Current research therefore focuses on whether and to what extent microorganisms or enzymes can degrade these NP. In this study, we addressed the question of what information isothermal titration calorimetry, which tracks the heat of reaction of the chain scission of a polyester, can provide about the kinetics and completeness of the degradation process. The majority of the heat represents the cleavage energy of the ester bonds in polymer backbones providing real-time kinetic information. Calorimetry operates even in complex matrices. Using the example of the cutinase-catalyzed degradation of polyethylene terephthalate (PET) nanoparticles, we found that calorimetry (isothermal titration calorimetry-ITC) in combination with thermokinetic models is excellently suited for an in-depth analysis of the degradation processes of NP. For instance, we can separately quantify i) the enthalpy of surface adsorption ∆AdsH = 129 ± 2 kJ mol-1, ii) the enthalpy of the cleavage of the ester bonds ∆EBH = -58 ± 1.9 kJ mol-1 and the apparent equilibrium constant of the enzyme substrate complex K = 0.046 ± 0.015 g L-1. It could be determined that the heat production of PET NP degradation depends to 95% on the reaction heat and only to 5% on the adsorption heat. The fact that the percentage of cleaved ester bonds (η = 12.9 ± 2.4%) is quantifiable with the new method is of particular practical importance. The new method promises a quantification of enzymatic and microbial adsorption to NP and their degradation in mimicked real-world aquatic conditions.
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Affiliation(s)
- Kristina Vogel
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, D-04318 Leipzig, Germany; Institute for Drug Discovery, Leipzig University Medical School, Leipzig University, Bruederstr, 34, D-04103 Leipzig, Germany
| | - Ren Wei
- Department of Biotechnology and Enzyme Catalysis, Institute for Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany.
| | - Lara Pfaff
- Department of Biotechnology and Enzyme Catalysis, Institute for Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany
| | - Daniel Breite
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, D-04318 Leipzig, Germany
| | - Hassan Al-Fathi
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, D-04318 Leipzig, Germany
| | | | - Irina Estrela-Lopis
- Institute for Medical Physics and Biophysics, Medical Faculty, Leipzig University, Härtelstr, 16-18, D-04107 Leipzig, Germany
| | - Tom Venus
- Institute for Medical Physics and Biophysics, Medical Faculty, Leipzig University, Härtelstr, 16-18, D-04107 Leipzig, Germany
| | - Agnes Schulze
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, D-04318 Leipzig, Germany
| | - Hauke Harms
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, D-04318 Leipzig, Germany
| | - Uwe T Bornscheuer
- Department of Biotechnology and Enzyme Catalysis, Institute for Biochemistry, University of Greifswald, Felix-Hausdorff-Str. 4, D-17487 Greifswald, Germany
| | - Thomas Maskow
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research - UFZ, Permoserstraße 15, D-04318 Leipzig, Germany.
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4
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Tetlow IJ, Bertoft E. A Review of Starch Biosynthesis in Relation to the Building Block-Backbone Model. Int J Mol Sci 2020; 21:E7011. [PMID: 32977627 PMCID: PMC7582286 DOI: 10.3390/ijms21197011] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 01/31/2023] Open
Abstract
Starch is a water-insoluble polymer of glucose synthesized as discrete granules inside the stroma of plastids in plant cells. Starch reserves provide a source of carbohydrate for immediate growth and development, and act as long term carbon stores in endosperms and seed tissues for growth of the next generation, making starch of huge agricultural importance. The starch granule has a highly complex hierarchical structure arising from the combined actions of a large array of enzymes as well as physicochemical self-assembly mechanisms. Understanding the precise nature of granule architecture, and how both biological and abiotic factors determine this structure is of both fundamental and practical importance. This review outlines current knowledge of granule architecture and the starch biosynthesis pathway in relation to the building block-backbone model of starch structure. We highlight the gaps in our knowledge in relation to our understanding of the structure and synthesis of starch, and argue that the building block-backbone model takes accurate account of both structural and biochemical data.
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Affiliation(s)
- Ian J. Tetlow
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, ON N1G 2W1, Canada
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5
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Pfister B, Zeeman SC, Rugen MD, Field RA, Ebenhöh O, Raguin A. Theoretical and experimental approaches to understand the biosynthesis of starch granules in a physiological context. PHOTOSYNTHESIS RESEARCH 2020; 145:55-70. [PMID: 31955343 PMCID: PMC7308250 DOI: 10.1007/s11120-019-00704-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
Starch, a plant-derived insoluble carbohydrate composed of glucose polymers, is the principal carbohydrate in our diet and a valuable raw material for industry. The properties of starch depend on the arrangement of glucose units within the constituent polymers. However, key aspects of starch structure and the underlying biosynthetic processes are not well understood, limiting progress towards targeted improvement of our starch crops. In particular, the major component of starch, amylopectin, has a complex three-dimensional, branched architecture. This architecture stems from the combined actions of a multitude of enzymes, each having broad specificities that are difficult to capture experimentally. In this review, we reflect on experimental approaches and limitations to decipher the enzymes' specificities and explore possibilities for in silico simulations of these activities. We believe that the synergy between experimentation and simulation is needed for the correct interpretation of experimental data and holds the potential to greatly advance our understanding of the overall starch biosynthetic process. We furthermore propose that the formation of glucan secondary structures, concomitant with its synthesis, is a previously overlooked factor that directly affects amylopectin architecture through its impact on enzyme function.
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Affiliation(s)
- Barbara Pfister
- Department of Biology, Institute of Molecular Plant Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Samuel C Zeeman
- Department of Biology, Institute of Molecular Plant Biology, ETH Zurich, 8092, Zurich, Switzerland
| | - Michael D Rugen
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Robert A Field
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Oliver Ebenhöh
- Department of Biology, Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, 40225, Düsseldorf, Germany
- Department of Biology, Cluster of Excellence on Plant Sciences, Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Adélaïde Raguin
- Department of Biology, Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, 40225, Düsseldorf, Germany.
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6
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Das S, Behera S, Balasubramanian S. Orientational Switch of the Lipase A Enzyme at the Oil-Water Interface: An Order of Magnitude Increase in Turnover Rate with a Single Surfactant Tag Explained. J Phys Chem Lett 2020; 11:2977-2982. [PMID: 32202805 DOI: 10.1021/acs.jpclett.0c00470] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Interfacially active lipases can be immobilized at a biphasic interface to enhance turnover recyclability and to facilitate product separation. Extensive coarse-grained molecular dynamics simulations of lipase A (LipA) from Bacillus subtilis show a bimodal orientational distribution of the enzyme at an oil-water interface, arising from its ellipsoidal Janus particle-like character. The relative orientational preference can be tuned by pH. The simulations rationalize a rare experimental observation of an order of magnitude increase in the turnover rate of this lipase upon its noncovalent tagging by a single surfactant molecule at the interface, compared to its rate in bulk water. The adsorption free energy, the interfacial activation, a decrease in the number of orientational fluctuations, and an increased rate of translational diffusion, to all of which the Janus character of LipA contributes, are the factors responsible for this enhancement. This study can spur further investigations of the Janus behavior of enzymes to enhance their activity as well as to stabilize the biphasic emulsion needed for interfacial catalysis.
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Affiliation(s)
- Sudip Das
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Sudarshan Behera
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Sundaram Balasubramanian
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
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7
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Fu B, Brown C, Mäler L. Expression and Purification of DGD2, a Chloroplast Outer Membrane-Associated Glycosyltransferase for Galactolipid Synthesis. Biochemistry 2020; 59:999-1009. [PMID: 32067450 DOI: 10.1021/acs.biochem.0c00028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Galactolipids are characteristic lipids of the photosynthetic membranes. They are highly enriched in the chloroplast and are present in photosystem structures. There are two major types of galactolipids, i.e., monogalactosyldiacylglycerol and digalactosyldiacylglycerol (DGDG) in chloroplastic membranes, which amount to ∼50 and ∼20 mol % of the total chloroplast lipids, respectively. Under phosphate-limiting conditions, the amount of DGDG increases dramatically for rescuing phosphate from phospholipids. In Arabidopsis thaliana, the gene digalactosyldiacylglycerol synthase 2 (DGD2) encodes a membrane-associated glycosyltransferase. The gene expression is highly responsive to phosphate starvation and is significantly upregulated in this case. To understand the molecular mechanism of DGD2, we established a protocol for DGD2 expression and purification in an Escherichia coli-based system. The work involved optimization of the expression condition and the purification protocol and a careful selection of buffer additives. It was found that a removal of around 70 C-terminal residues was necessary to produce a homogeneous monomeric protein sample with high purity, which was highly active. The purified sample was characterized by an activity assay for enzyme kinetics in which a range of membrane mimetics with different lipid compositions were used. The results demonstrate that DGD2 activity is stimulated by the presence of negatively charged lipids, which highlight the importance of the membrane environment in modulating the enzyme's activity. The study also paves way for future biophysical and structural studies of the enzyme.
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Affiliation(s)
- Biao Fu
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Christian Brown
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Lena Mäler
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.,Department of Chemistry, University of Umeå, SE-901 87 Umeå, Sweden
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8
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Zhang H, Fan Z, Li J, Han L. A comparative study on enzyme adsorption and hydrolytic performance of different scale corn stover by two-step kinetics. BIORESOURCE TECHNOLOGY 2019; 282:384-389. [PMID: 30884458 DOI: 10.1016/j.biortech.2019.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
To investigate the effect of two-step kinetics on enzyme adsorption and hydrolytic properties of different structural substrates at low enzyme doses. The two-step kinetic experiments of ultrafine grinding (UGCS) and sieve-based grinding corn stover (SGCS) were performed respectively with enzyme loading of 2.5 + 2.5 FPU/g and 5 + 5 FPU/g. The different performance of these two samples were illustrated by characterizing the particle size distribution, SEM and XPS. The results showed that ultrafine grinding can promote the structural properties which is beneficial to adsorption and hydrolysis. The main factors influencing adsorption kinetics are enzyme concentration and the surface cellulose amount. Pre-adsorbed enzyme has no effects on the subsequent enzyme adsorption quantity but produces some small competitive and impeditive effects. The hydrolysis kinetics mainly depend on the structure of the substrate and its complexity of hydrolysis. The two-step hydrolysis didn't promote the total sugar yield under the same enzyme concentration, but the first step contributed more to the total sugar yield.
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Affiliation(s)
- Haiyan Zhang
- College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Hai-Dian District, Beijing 100083, PR China
| | - Zhiliang Fan
- Department of Biological and Agricultural Engineering, University of California, Davis, CA 95616, United States
| | - Junbao Li
- College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Hai-Dian District, Beijing 100083, PR China
| | - Lujia Han
- College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Hai-Dian District, Beijing 100083, PR China.
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9
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Badino SF, Kari J, Christensen SJ, Borch K, Westh P. Direct kinetic comparison of the two cellobiohydrolases Cel6A and Cel7A from Hypocrea jecorina. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1739-1745. [DOI: 10.1016/j.bbapap.2017.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/25/2017] [Accepted: 08/14/2017] [Indexed: 01/17/2023]
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10
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Seki M, Ohara T, Hearn TJ, Frank A, da Silva VCH, Caldana C, Webb AAR, Satake A. Adjustment of the Arabidopsis circadian oscillator by sugar signalling dictates the regulation of starch metabolism. Sci Rep 2017; 7:8305. [PMID: 28814797 PMCID: PMC5559614 DOI: 10.1038/s41598-017-08325-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 07/20/2017] [Indexed: 02/02/2023] Open
Abstract
Arabidopsis plants store part of the carbon fixed by photosynthesis as starch to sustain growth at night. Two competing hypotheses have been proposed to explain this diel starch turnover based on either the measurement of starch abundance with respect to circadian time, or the sensing of sugars to feedback to the circadian oscillator to dynamically adjust the timing of starch turnover. We report a phase oscillator model that permitted derivation of the ideal responses of the circadian regulation of starch breakdown to maintain sucrose homeostasis. Testing the model predictions using a sugar-unresponsive mutant of Arabidopsis demonstrated that the dynamics of starch turnover arise from the circadian clock measuring and responding to the rate of change of cellular sucrose. Our theory and experiments suggest that starch turnover is controlled by the circadian clock acting as a dynamic homeostat responding to sucrose signals to maintain carbon homeostasis.
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Affiliation(s)
- Motohide Seki
- 0000 0001 2242 4849grid.177174.3Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 Japan
| | - Takayuki Ohara
- 0000 0001 2242 4849grid.177174.3Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 Japan ,0000 0001 2173 7691grid.39158.36Graduate School of Environmental Science, Hokkaido University, N10W5, Sapporo, 060-0810 Japan
| | - Timothy J. Hearn
- 0000000121885934grid.5335.0Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA United Kingdom
| | - Alexander Frank
- 0000000121885934grid.5335.0Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA United Kingdom
| | - Viviane C. H. da Silva
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Rua Giuseppe Máximo Scolfaro 10.000 CEP 13083-100 Campinas, São Paulo, Brazil
| | - Camila Caldana
- Brazilian Bioethanol Science and Technology Laboratory (CTBE), Rua Giuseppe Máximo Scolfaro 10.000 CEP 13083-100 Campinas, São Paulo, Brazil ,Max Planck Partner Group at Brazilian Bioethanol Science and Technology Laboratory, Campinas, SP Brazil
| | - Alex A. R. Webb
- 0000000121885934grid.5335.0Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA United Kingdom
| | - Akiko Satake
- 0000 0001 2242 4849grid.177174.3Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 Japan
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11
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Raguin A, Ebenhöh O. Design starch: stochastic modeling of starch granule biogenesis. Biochem Soc Trans 2017; 45:885-893. [PMID: 28673938 PMCID: PMC5652221 DOI: 10.1042/bst20160407] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/15/2017] [Accepted: 05/19/2017] [Indexed: 12/03/2022]
Abstract
Starch is the most widespread and abundant storage carbohydrate in plants and the main source of carbohydrate in the human diet. Owing to its remarkable properties and commercial applications, starch is still of growing interest. Its unique granular structure made of intercalated layers of amylopectin and amylose has been unraveled thanks to recent progress in microscopic imaging, but the origin of such periodicity is still under debate. Both amylose and amylopectin are made of linear chains of α-1,4-bound glucose residues, with branch points formed by α-1,6 linkages. The net difference in the distribution of chain lengths and the branching pattern of amylose (mainly linear), compared with amylopectin (racemose structure), leads to different physico-chemical properties. Amylose is an amorphous and soluble polysaccharide, whereas amylopectin is insoluble and exhibits a highly organized structure of densely packed double helices formed between neighboring linear chains. Contrarily to starch degradation that has been investigated since the early 20th century, starch production is still poorly understood. Most enzymes involved in starch growth (elongation, branching, debranching, and partial hydrolysis) are now identified. However, their specific action, their interplay (cooperative or competitive), and their kinetic properties are still largely unknown. After reviewing recent results on starch structure and starch growth and degradation enzymatic activity, we discuss recent results and current challenges for growing polysaccharides on granular surface. Finally, we highlight the importance of novel stochastic models to support the analysis of recent and complex experimental results, and to address how macroscopic properties emerge from enzymatic activity and structural rearrangements.
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Affiliation(s)
- Adélaïde Raguin
- Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, Düsseldorf 40225, Germany
| | - Oliver Ebenhöh
- Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, Düsseldorf 40225, Germany
- Cluster of Excellence on Plant Sciences, Institute of Quantitative and Theoretical Biology, Heinrich-Heine University, Düsseldorf 40225, Germany
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12
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Kari J, Andersen M, Borch K, Westh P. An Inverse Michaelis–Menten Approach for Interfacial Enzyme Kinetics. ACS Catal 2017. [DOI: 10.1021/acscatal.7b00838] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jeppe Kari
- Dept.
of Science and Environment, Roskilde University, 1 Universitetsvej, Building 28, DK-4000 Roskilde, Denmark
| | - Morten Andersen
- Dept.
of Science and Environment, Roskilde University, 1 Universitetsvej, Building 28, DK-4000 Roskilde, Denmark
| | - Kim Borch
- Novozymes A/S, Krogshøjvej
36, DK-2880 Bagsværd, Denmark
| | - Peter Westh
- Dept.
of Science and Environment, Roskilde University, 1 Universitetsvej, Building 28, DK-4000 Roskilde, Denmark
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13
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Zhdanov VP, Agnarsson B, Höök F. Kinetics of enzyme-mediated hydrolysis of lipid vesicles. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Abstract
An appreciable part of enzymes operating in vivo is associated with lipid membranes. The function of such enzymes can be influenced by the presence of domains containing proteins and/or composed of different lipids. The corresponding experimental model-system studies can be performed under well controlled conditions, e.g., on a planar supported lipid bilayer or surface-immobilized vesicles. To clarify what may happen in such systems, we propose general kinetic equations describing the enzyme-catalyzed substrate conversion occurring via the Michaelis-Menten (MM) mechanism on a membrane with domains which do not directly participate in reaction. For two generic situations when a relatively slow reaction takes place primarily in or outside domains, we take substrate saturation and lateral substrate-substrate interactions at domains into account and scrutinize the dependence of the reaction rate on the average substrate coverage. With increasing coverage, depending on the details, the reaction rate reaches saturation via an inflection point or monotonously as in the conventional MM case. In addition, we show analytically the types of reaction kinetics occurring primarily at domain boundaries. In the physically interesting situation when the domain growth is fast on the reaction time scale, the latter kinetics are far from conventional. The opposite situation when the reaction is fast and controlled by diffusion has been studied by using the Monte Carlo technique. The corresponding results indicate that the dependence of the reaction kinetics on the domain size may be weak.
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Affiliation(s)
- Vladimir P Zhdanov
- Division of Biological Physics, Department of Applied Physics, Chalmers University of Technology, SE-41296 Göteborg, Sweden. Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk 630090, Russia
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15
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Varjú I, Tenekedjiev K, Keresztes Z, Pap AE, Szabó L, Thelwell C, Longstaff C, Machovich R, Kolev K. Fractal Kinetic Behavior of Plasmin on the Surface of Fibrin Meshwork. Biochemistry 2014; 53:6348-56. [DOI: 10.1021/bi500661m] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Imre Varjú
- Department
of Medical Biochemistry, Semmelweis University, 1094 Budapest, Hungary
| | - Kiril Tenekedjiev
- Department
of Information Technology, Nikola Vaptsarov Naval Academy, 9026 Varna, Bulgaria
| | | | - Andrea Edit Pap
- Microtechnology
Department, Institute of Technical Physics and Materials Science,
Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1121 Budapest, Hungary
| | | | - Craig Thelwell
- Biotherapeutics
Division, Haemostasis Section, National Institute for Biological Standards and Control, South Mimms, Herts, EN6 3QG, U.K
| | - Colin Longstaff
- Biotherapeutics
Division, Haemostasis Section, National Institute for Biological Standards and Control, South Mimms, Herts, EN6 3QG, U.K
| | - Raymund Machovich
- Department
of Medical Biochemistry, Semmelweis University, 1094 Budapest, Hungary
| | - Krasimir Kolev
- Department
of Medical Biochemistry, Semmelweis University, 1094 Budapest, Hungary
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16
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Pokhilko A, Flis A, Sulpice R, Stitt M, Ebenhöh O. Adjustment of carbon fluxes to light conditions regulates the daily turnover of starch in plants: a computational model. MOLECULAR BIOSYSTEMS 2014; 10:613-27. [PMID: 24413396 DOI: 10.1039/c3mb70459a] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the light, photosynthesis provides carbon for metabolism and growth. In the dark, plant growth depends on carbon reserves that were accumulated during previous light periods. Many plants accumulate part of their newly-fixed carbon as starch in their leaves in the day and remobilise it to support metabolism and growth at night. The daily rhythms of starch accumulation and degradation are dynamically adjusted to the changing light conditions such that starch is almost but not totally exhausted at dawn. This requires the allocation of a larger proportion of the newly fixed carbon to starch under low carbon conditions, and the use of information about the carbon status at the end of the light period and the length of the night to pace the rate of starch degradation. This regulation occurs in a circadian clock-dependent manner, through unknown mechanisms. We use mathematical modelling to explore possible diurnal mechanisms regulating the starch level. Our model combines the main reactions of carbon fixation, starch and sucrose synthesis, starch degradation and consumption of carbon by sink tissues. To describe the dynamic adjustment of starch to daily conditions, we introduce diurnal regulators of carbon fluxes, which modulate the activities of the key steps of starch metabolism. The sensing of the diurnal conditions is mediated in our model by the timer α and the "dark sensor"β, which integrate daily information about the light conditions and time of the day through the circadian clock. Our data identify the β subunit of SnRK1 kinase as a good candidate for the role of the dark-accumulated component β of our model. The developed novel approach for understanding starch kinetics through diurnal metabolic and circadian sensors allowed us to explain starch time-courses in plants and predict the kinetics of the proposed diurnal regulators under various genetic and environmental perturbations.
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Affiliation(s)
- Alexandra Pokhilko
- Institute for Complex Systems and Mathematical Biology, University of Aberdeen, UK
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