151
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Gairola K, Smirnova I. Hydrothermal pentose to furfural conversion and simultaneous extraction with SC-CO2--kinetics and application to biomass hydrolysates. Bioresour Technol 2012; 123:592-598. [PMID: 22947445 DOI: 10.1016/j.biortech.2012.07.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 07/09/2012] [Accepted: 07/11/2012] [Indexed: 06/01/2023]
Abstract
This work explores hydrothermal d-xylose and hemicellulose to furfural conversion coupled with simultaneous furfural extraction by SC-CO(2) and the underlying reaction pathway. A maximum furfural yield of 68% was attained from d-xylose at 230°C and 12MPa. Additionally missing kinetic data for l-arabinose to furfural conversion was provided, showing close similarity to d-xylose. Furfural yields from straw and brewery waste hydrolysates were significantly lower than those obtained from model compounds, indicating side reactions with other hydrolysate components. Simultaneous furfural extraction by SC-CO(2) significantly increased extraction yield in all cases. The results indicate that furfural reacts with intermediates of pentose dehydration. The proposed processing route can be well integrated into existing lignocellulose biorefinery concepts.
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Affiliation(s)
- Krishan Gairola
- Institute of Thermal Separation Processes, Hamburg University of Technology, Eissendorfer Strasse 38, 21073 Hamburg, Germany.
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152
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Heils R, Sont A, Bubenheim P, Liese A, Smirnova I. Integration of Enzymatic Catalysts in a Reactive Distillation Column with Structured Packings. Ind Eng Chem Res 2012. [DOI: 10.1021/ie300837v] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rene Heils
- Thermal Separation
Processes, Hamburg University of Technology, Eißendorfer Str. 38, D-21073 Hamburg, Germany
| | - Annika Sont
- Thermal Separation
Processes, Hamburg University of Technology, Eißendorfer Str. 38, D-21073 Hamburg, Germany
| | - Paul Bubenheim
- Technical Biocatalysis, Hamburg University of Technology, Denickestr.
15, D-21073 Hamburg, Germany
| | - Andreas Liese
- Technical Biocatalysis, Hamburg University of Technology, Denickestr.
15, D-21073 Hamburg, Germany
| | - Irina Smirnova
- Thermal Separation
Processes, Hamburg University of Technology, Eißendorfer Str. 38, D-21073 Hamburg, Germany
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153
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Glembin P, Kerner M, Smirnova I. Mizellare In-situ-Extraktion hydrophober Substanzen aus Mikroalgenkulturen. CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201250288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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154
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Mehling T, Ingram T, Smirnova I. Methoden zur Auslegung tensidbasierter (Trenn-)Prozesse. CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201250307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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155
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156
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Heils R, Cumana S, Hilterhaus L, Liese A, Smirnova I. Anwendung von porösen Silika-Materialien für die Einbringung von Enzymen in neuen Reaktions- und Trennsystemen. CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201250323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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157
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Smirnova I, Liese A, Winter R. Enzymkatalysierte Prozesse unter Hochdruck: Lohnt es sich? CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201250449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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158
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Jakobtorweihen S, Ingram T, Smirnova I, Keil F. Vorhersage des Verteilungsverhaltens geladener Stoffe in Biomembranen mit molekularen Methoden. CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201250454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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159
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160
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Ingram T, Storm S, Glembin P, Bendt S, Huber D, Mehling T, Smirnova I. Aqueous Surfactant Two-Phase Systems for the Continuous Countercurrent Cloud Point Extraction. CHEM-ING-TECH 2012. [DOI: 10.1002/cite.201100256] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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161
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Schworer S, Smirnova I, Poltorak A. Genetic screen reveals CYLD as a regulator of the balance between inflammation and cell death (180.18). The Journal of Immunology 2012. [DOI: 10.4049/jimmunol.188.supp.180.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
During the innate immune response to infection, a critical balance exists between the production pro-inflammatory cytokines and immune cell death. Cell death through RIP1-mediated regulated necrosis is emerging as an important mechanism through which cells respond to certain viral pathogens. To determine novel regulatory mechanisms of this signaling pathway, we studied cellular responses to TLR agonists in evolutionarily divergent wild-derived mice (MOLF/Ei) in a forward genetic screen of TLR-induced necrosis. In contrast to C57BL/6 macrophages, which are susceptible to TLR-induced necrosis, MOLF macrophages are resistant to death induced through this pathway. Using an N2 panel and forward genetic analysis, we found a locus on chromosome 8 that confers resistance to TLR-induced necrosis. Through gene expression analysis, allelic bias studies, and siRNA knockdown in peritoneal macrophages, we concluded that a genetic difference in CYLD confers the differential susceptibility to TLR-induced necrosis between B6 and MOLF macrophages. This difference was revealed through analysis of the regulation of CYLD mRNA splicing following TLR stimulation. The molecular defect that results in greater survival of MOLF cells appears to be mutually exclusive splicing of CYLD mRNA in activated or quiescent cells. Through our use of wild-derived mice in forward genetic analysis, we were able to uncover a key function of naturally occurring CYLD splice isoforms in a physiologic setting.
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Affiliation(s)
- Stephen Schworer
- 1Pathology, Program in Immunology, Tufts University, Boston, MA
- 2Medical Scientist Training Program, Tufts University, Boston, MA
| | - Irina Smirnova
- 1Pathology, Program in Immunology, Tufts University, Boston, MA
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162
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García-González C, Uy J, Alnaief M, Smirnova I. Preparation of tailor-made starch-based aerogel microspheres by the emulsion-gelation method. Carbohydr Polym 2012. [DOI: 10.1016/j.carbpol.2012.02.023] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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163
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Strompen S, Weiss M, Ingram T, Smirnova I, Gröger H, Hilterhaus L, Liese A. Kinetic investigation of a solvent-free, chemoenzymatic reaction sequence towards enantioselective synthesis of a β-amino acid ester. Biotechnol Bioeng 2012; 109:1479-89. [PMID: 22275046 DOI: 10.1002/bit.24422] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 12/10/2011] [Accepted: 12/19/2011] [Indexed: 11/10/2022]
Abstract
A solvent-free, chemoenzymatic reaction sequence for the enantioselective synthesis of β-amino acid esters has been kinetically and thermodynamically characterized. The coupled sequence comprises a thermal aza-Michael addition of cheap starting materials and a lipase catalyzed aminolysis for the kinetic resolution of the racemic ester. Excellent ee values of >99% were obtained for the β-amino acid ester at 60% conversion. Kinetic constants for the aza-Michael addition were obtained by straightforward numerical integration of second-order rate equations and nonlinear fitting of the progress curves. A different strategy had to be devised for the biocatalytic reaction. Initially, a simplified Michaelis-Menten model including product inhibition was developed for the reaction running in THF as an organic solvent. Activity based parameters were used instead of concentrations in order to facilitate the transfer of the kinetic model to the solvent-free system. Observed solvent effects not accounted for by the use of thermodynamic activities were incorporated into the kinetic model. Enzyme deactivation was observed to depend on the ratio of the applied substrates and also included in the kinetic model. The developed simple model is in very good agreement with the experimental data and allows the simulation and optimization of the solvent-free process.
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Affiliation(s)
- Simon Strompen
- Hamburg University of Technology, Institute of Technical Biocatalysis, Denickestr. 15, 21073 Hamburg, Germany
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164
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Mehling T, Ingram T, Smirnova I. Experimental methods and prediction with COSMO-RS to determine partition coefficients in complex surfactant systems. Langmuir 2012; 28:118-124. [PMID: 22091584 DOI: 10.1021/la2028274] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Surfactant-based separation processes are a promising alternative to conventional organic solvent processes. A crucial parameter to describe the efficiency of such processes is the partition coefficient between the surfactant aggregates (micelles) and the aqueous bulk phase. In this work, several experimental methods to determine these partition coefficients (micellar liquid chromatography, micellar enhanced ultrafiltration, and cloud point extraction) are evaluated and compared. In addition, these results are compared to predictions with the thermodynamic model COSMO-RS. In particular, systems with the nonionic surfactant TritonX-100 are studied. The partition equilibria of various solutes (pyrene, naphthalene, phenanthrene, phenol, 3-methoxyphenol, and vanillin) and the influence of different additives (alcohols) are investigated. All experimental methods show very good reproducibility. Moreover, the results from different methods are in good agreement, supplementing one another concerning the temperature ranges. Notably, the COSMO-RS model is capable of predicting partition coefficients between micelles and water in the investigated temperature range and at different alcohol concentrations. The results demonstrate the potential of the model COSMO-RS to facilitate the selection of optimized process parameters for a given separation problem. By predicting partition equilibria in multicomponent systems, the selection of surfactant, temperature, and appropriate additives can be facilitated.
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Affiliation(s)
- Tanja Mehling
- Institute of Thermal Separation Processes, Hamburg University of Technology, Hamburg 21073, Germany.
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165
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García-González CA, Carenza E, Zeng M, Smirnova I, Roig A. Design of biocompatible magnetic pectin aerogel monoliths and microspheres. RSC Adv 2012. [DOI: 10.1039/c2ra21500d] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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166
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Zetzl C, Gairola K, Kirsch C, Perez-Cantu L, Smirnova I. Ein-Reaktor-Konzept zur Hochdruckfraktionierung lignocellulosehaltiger Biomasse. CHEM-ING-TECH 2011. [DOI: 10.1002/cite.201100161] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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167
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Abstract
The sucrose permease (CscB) and lactose permease (LacY) of Escherichia coli belong to the oligosaccharide/H(+) symporter subfamily of the major facilitator superfamily, and both catalyze sugar/H(+) symport across the cytoplasmic membrane. Thus far, there is no common substrate for the two permeases; CscB transports sucrose, and LacY is highly specific for galactopyranosides. Determinants for CscB sugar specificity are unclear, but the structural organization of key residues involved in sugar binding appears to be similar in CscB and LacY. In this study, several sugars containing galactopyranosyl, glucopyranosyl, or fructofuranosyl moieties were tested for transport with cells overexpressing either CscB or LacY. CscB recognizes not only sucrose but also fructose and lactulose, but glucopyranosides are not transported and do not inhibit sucrose transport. The findings indicate that CscB exhibits practically no specificity with respect to the glucopyranosyl moiety of sucrose. Inhibition of sucrose transport by CscB tested with various fructofuranosides suggests that the C(3)-OH group of the fructofuranosyl ring may be important for recognition by CscB. Lactulose is readily transported by LacY, where specificity is directed toward the galactopyranosyl ring, and the affinity of LacY for lactulose is similar to that observed for lactose. The studies demonstrate that the substrate specificity of CscB is directed toward the fructofuranosyl moiety of the substrate, while the specificity of LacY is directed toward the galactopyranosyl moiety.
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Affiliation(s)
- Junichi Sugihara
- Department of Physiology, University of California Los Angeles, Los Angeles, California 90095-7327, United States
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168
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Abstract
Crystal structures of the lactose permease of Escherichia coli (LacY) reveal 12, mostly irregular transmembrane α-helices surrounding a large cavity open to the cytoplasm and a tightly sealed periplasmic side (inward-facing conformation) with the sugar-binding site at the apex of the cavity and inaccessible from the periplasm. However, LacY is highly dynamic, and binding of a galactopyranoside causes closing of the inward-facing cavity with opening of a complementary outward-facing cavity. Therefore, the coupled, electrogenic translocation of a sugar and a proton across the cytoplasmic membrane via LacY very likely involves a global conformational change that allows alternating access of sugar- and H(+)-binding sites to either side of the membrane. Here the various biochemical and biophysical approaches that provide strong support for the alternating access mechanism are reviewed. Evidence is also presented indicating that opening of the periplasmic cavity is probably the limiting step for binding and perhaps transport.
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Affiliation(s)
- Irina Smirnova
- Department of Physiology and Department of Microbiology, University of California, Los Angeles, California 90095, United States
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169
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Wille S, Mokrushina L, Schwarze M, Smirnova I, Schomäcker R, Arlt W. Partition Coefficients for Continuous Micellar Reaction Processes. Chem Eng Technol 2011. [DOI: 10.1002/ceat.201100359] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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170
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171
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172
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Hentzschel CM, Alnaief M, Smirnova I, Sakmann A, Leopold CS. Enhancement of griseofulvin release from liquisolid compacts. Eur J Pharm Biopharm 2011; 80:130-5. [PMID: 21846502 DOI: 10.1016/j.ejpb.2011.08.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 07/30/2011] [Accepted: 08/01/2011] [Indexed: 10/17/2022]
Abstract
The potential of hydrophilic aerogel formulations and liquisolid systems to improve the release of poorly soluble drugs was investigated using griseofulvin as model drug. The in vitro release rates of this drug formulated as directly compressed tablets containing crystalline griseofulvin were compared to aerogel tablets with the drug adsorbed onto hydrophilic silica aerogel and to liquisolid compacts containing the drug dissolved or suspended in PEG 300. Furthermore, the commonly used carrier and coating materials in liquisolid systems Avicel® and Aerosil® were replaced by Neusilin®, an amorphous magnesium aluminometasilicate with an extremely high specific surface area of 339 m²/g to improve the liquisolid approach. Both the liquisolid compacts containing the drug dissolved in PEG 300 and the aerogel tablets showed a considerably faster drug release than the directly compressed tablets. With liquisolid compacts containing the drug suspended in PEG 300, the release rate increased with rising fraction of dissolved drug in the liquid portion. It could be shown that Neusilin® with its sevenfold higher liquid adsorption capacity than the commonly used Avicel® and Aerosil® allows the production of liquisolid formulations with lower tablet weights.
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Affiliation(s)
- C M Hentzschel
- Institute of Pharmacy, Department of Pharmaceutical Technology, University of Hamburg, Hamburg, Germany
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173
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Verevkin SP, Emel’yanenko VN, Kozlova SA, Smirnova I, Arlt W. Experimental and Theoretical Study of Chemical Equilibria in the Reacting System of the di-Alkyl Carbonate Synthesis. Ind Eng Chem Res 2011. [DOI: 10.1021/ie2006824] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sergey P. Verevkin
- Department of Physical Chemistry, University of Rostock, Dr.-Lorenz-Weg. 1, 18059 Rostock, Germany
| | - Vladimir N. Emel’yanenko
- Department of Physical Chemistry, University of Rostock, Dr.-Lorenz-Weg. 1, 18059 Rostock, Germany
| | - Svetlana A. Kozlova
- Department of Physical Chemistry, University of Rostock, Dr.-Lorenz-Weg. 1, 18059 Rostock, Germany
| | - Irina Smirnova
- Lehrstuhl für Thermische Verfahrenstechnik der Universität Erlangen Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Wolfgang Arlt
- Lehrstuhl für Thermische Verfahrenstechnik der Universität Erlangen Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
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174
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Devesse L, Smirnova I, Lönneborg R, Kapp U, Brzezinski P, Leonard GA, Dian C. Crystal structures of DntR inducer binding domains in complex with salicylate offer insights into the activation of LysR-type transcriptional regulators. Mol Microbiol 2011; 81:354-67. [DOI: 10.1111/j.1365-2958.2011.07673.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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175
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176
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177
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Ingram T, Wörmeyer K, Lima JCI, Bockemühl V, Antranikian G, Brunner G, Smirnova I. Comparison of different pretreatment methods for lignocellulosic materials. Part I: conversion of rye straw to valuable products. Bioresour Technol 2011; 102:5221-5228. [PMID: 21349703 DOI: 10.1016/j.biortech.2011.02.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 12/08/2010] [Accepted: 02/01/2011] [Indexed: 05/30/2023]
Abstract
The conversion of lignocellulose to valuable products requires I: a fractionation of the major components hemicellulose, cellulose, and lignin, II: an efficient method to process these components to higher valued products. The present work compares liquid hot water (LHW) pretreatment to the soda pulping process and to the ethanol organosolv pretreatment using rye straw as a single lignocellulosic material. The organosolv pretreated rye straw was shown to require the lowest enzyme loading in order to achieve a complete saccharification of cellulose to glucose. At biomass loadings of up to 15% (w/w) cellulose conversion of LHW and organosolv pretreated lignocellulose was found to be almost equal. The soda pulping process shows lower carbohydrate and lignin recoveries compared to the other two processes. In combination with a detailed analysis of the different lignins obtained from the three pretreatment methods, this work gives an overview of the potential products from different pretreatment processes.
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Affiliation(s)
- Thomas Ingram
- Hamburg University of Technology, Institute of Thermal Separation Processes, Eißendorfer Straße 38, D-21073 Hamburg, Germany.
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178
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Alnaief M, Alzaitoun M, García-González C, Smirnova I. Preparation of biodegradable nanoporous microspherical aerogel based on alginate. Carbohydr Polym 2011. [DOI: 10.1016/j.carbpol.2010.12.060] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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179
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Wörmeyer K, Ingram T, Saake B, Brunner G, Smirnova I. Comparison of different pretreatment methods for lignocellulosic materials. Part II: Influence of pretreatment on the properties of rye straw lignin. Bioresour Technol 2011; 102:4157-4164. [PMID: 21208799 DOI: 10.1016/j.biortech.2010.11.063] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 11/12/2010] [Accepted: 11/17/2010] [Indexed: 05/30/2023]
Abstract
Several processes have been suggested to convert various types of lignocellulosic biomass into lignin products and saccharides. This paper evaluates the suitability of an organosolv process, a process using soda, a hydrothermal process and a process developed in this work, called the "Aquasolve process" for inclusion into a lignocellulosic biorefinery concept. Part II of this paper investigates the influence of the different pretreatment processes on the properties of rye straw lignin and evaluates their ability to produce high recoveries of high quality lignin. Specifications for high quality lignin products are defined and the isolated lignin fractions are analysed by Klason lignin, carbohydrate and ash content, elemental analysis, thermo-gravimetric analysis, (31)P NMR, and size exclusion chromatography. The organosolv process shows the largest lignin recovery, followed by the soda and Aquasolve processes. Lignin products from the soda process, the Aquasolve process and with reservation the organosolv process show interesting properties for polymer applications.
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Affiliation(s)
- Kai Wörmeyer
- Hamburg University of Technology, Thermal Separation Processes, Eissendorfer Strasse 38, D-21073 Hamburg, Germany.
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180
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Scherf AK, Zetzl C, Smirnova I, Zettlitzer M, Vieth-Hillebrand A. Mobilisation of organic compounds from reservoir rocks through the injection of CO2 —Comparison of baseline characterization and laboratory experiments. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/j.egypro.2011.02.409] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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181
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182
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Smirnova I, Reimann J, von Ballmoos C, Chang HY, Gennis RB, Fee JA, Brzezinski P, Adelroth P. Functional role of Thr-312 and Thr-315 in the proton-transfer pathway in ba3 Cytochrome c oxidase from Thermus thermophilus. Biochemistry 2010; 49:7033-9. [PMID: 20677778 DOI: 10.1021/bi100749p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome ba(3) from Thermus thermophilus is a member of the family of B-type heme-copper oxidases, which have a low degree of sequence homology to the well-studied mitochondrial-like A-type enzymes. Recently, it was suggested that the ba(3) oxidase has only one pathway for the delivery of protons to the active site and that this pathway is spatially analogous to the K-pathway in the A-type oxidases [Chang, H.-Y., et al. (2009) Proc. Natl. Acad. Sci. U.S.A. 106, 16169-16173]. This suggested pathway includes two threonines at positions 312 and 315. In this study, we investigated the time-resolved reaction between fully reduced cytochrome ba(3) and O(2) in variants where Thr-312 and Thr-315 were modified. While in the A-type oxidases this reaction is essentially unchanged in variants with the K-pathway modified, in the Thr-312 --> Ser variant in the ba(3) oxidase both reactions associated with proton uptake from solution, the P(R) --> F and F --> O transitions, were slowed compared to those of wild-type ba(3). The observed time constants were slowed approximately 3-fold (for P(R) --> F, from 60 to approximately 170 mus in the wild type) and approximately 30-fold (for F --> O, from 1.1 to approximately 40 ms). In the Thr-315 --> Val variant, the F --> O transition was approximately 5-fold slower (5 ms) than for the wild-type oxidase, whereas the P(R) --> F transition displayed an essentially unchanged time constant. However, the uptake of protons from solution was a factor of 2 slower and decoupled from the optical P(R) --> F transition. Our results thus show that proton uptake is significantly and specifically inhibited in the two variants, strongly supporting the suggested involvement of T312 and T315 in the transfer of protons to the active site during O(2) reduction in the ba(3) oxidase.
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Affiliation(s)
- Irina Smirnova
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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183
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Gairola K, Kopf F, Zetzl C, Smirnova I, Bowra S, Seantier B. Extraktion von Proteinen aus Brauereirückständen mit unterkritischem Wasser. CHEM-ING-TECH 2010. [DOI: 10.1002/cite.201050249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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184
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Ingram T, Mehling T, Smirnova I. Tensid-basierte Trennprozesse: Einfluss von Elektrolyten auf Verteilungsgleichgewichte. CHEM-ING-TECH 2010. [DOI: 10.1002/cite.201050542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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185
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Cumana S, Götz K, Bohne S, Liese A, Müller J, Smirnova I, Roth S. Mesoporous Silica Monoliths for Enzyme-Catalyzed Reactions in Microfluidic Systems. CHEM-ING-TECH 2010. [DOI: 10.1002/cite.201050612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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186
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Alnaief M, Smirnova I, Antonyuk S, Heinrich S, Roth S. A Novel Process for Production of Aerogel Microspheres and their Coating with Polymeric Materials in a Spouted Bed. CHEM-ING-TECH 2010. [DOI: 10.1002/cite.201050513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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187
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Garcia-Celma JJ, Ploch J, Smirnova I, Kaback HR, Fendler K. Delineating electrogenic reactions during lactose/H+ symport. Biochemistry 2010; 49:6115-21. [PMID: 20568736 PMCID: PMC2907097 DOI: 10.1021/bi100492p] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 06/17/2010] [Indexed: 01/03/2023]
Abstract
Electrogenic reactions accompanying downhill lactose/H(+) symport catalyzed by the lactose permease of Escherichia coli (LacY) have been assessed using solid-supported membrane-based electrophysiology with improved time resolution. Rates of charge translocation generated by purified LacY reconstituted into proteoliposomes were analyzed over a pH range from 5.2 to 8.5, which allows characterization of two electrogenic steps in the transport mechanism: (i) a weak electrogenic reaction triggered by sugar binding and observed under conditions where H(+) translocation is abolished either by acidic pH or by a Glu325 --> Ala mutation in the H(+) binding site (this step with a rate constant of approximately 200 s(-1) for wild-type LacY leads to an intermediate proposed to represent an "occluded" state) and (ii) a major electrogenic reaction corresponding to 94% of the total charge translocated at pH 8, which is pH-dependent with a maximum rate of approximately 30 s(-1) and a pK of 7.5. This partial reaction is assigned to rate-limiting H(+) release on the cytoplasmic side of LacY during turnover. These findings together with previous electrophysiological results and biochemical-biophysical studies are included in an overall kinetic mechanism that allows delineation of the electrogenic steps in the reaction pathway.
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Affiliation(s)
- Juan J. Garcia-Celma
- Department of Biophysical Chemistry, Max-Planck-Institute of Biophysics, D-60438 Frankfurt/M, Germany
| | - Julian Ploch
- Department of Biophysical Chemistry, Max-Planck-Institute of Biophysics, D-60438 Frankfurt/M, Germany
| | | | - H. Ronald Kaback
- Department of Physiology
- Department of Microbiology and Immunology
- Department of Molecular Genetics
| | - Klaus Fendler
- Department of Biophysical Chemistry, Max-Planck-Institute of Biophysics, D-60438 Frankfurt/M, Germany
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188
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Wille S, Buggert M, Mokrushina L, Arlt W, Smirnova I. Effect of Electrolytes on Octanol-Water Partition Coefficients: Calculations with COSMO-RS. Chem Eng Technol 2010. [DOI: 10.1002/ceat.201000045] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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189
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Cuisset A, Nanobashvili L, Smirnova I, Bocquet R, Hindle F, Mouret G, Pirali O, Roy P, Sadovskií DA. Far-infrared high resolution synchrotron FTIR spectroscopy of the ν11 bending vibrational fundamental transition of dimethylsulfoxyde. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.04.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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190
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191
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Smirnova I, Kasho V, Sugihara J, Kaback HR. Probing of the rates of alternating access in LacY with Trp fluorescence. Proc Natl Acad Sci U S A 2009; 106:21561-6. [PMID: 19959662 PMCID: PMC2799877 DOI: 10.1073/pnas.0911434106] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Indexed: 11/18/2022] Open
Abstract
Sugar/H(+) symport by lactose permease (LacY) utilizes an alternating access mechanism in which sugar and H(+) binding sites in the middle of the molecule are alternatively exposed to either side of the membrane by sequential opening and closing of inward- and outward-facing hydrophilic cavities. Here, we introduce Trp residues on either side of LacY where they are predicted to be in close proximity to side chains of natural Trp quenchers in either the inward- or outward-facing conformers. In the inward-facing conformer, LacY is tightly packed on the periplasmic side, and Trp residues placed at positions 245 (helix VII) or 378 (helix XII) are in close contact with His-35 (helix I) or Lys-42 (helix II), respectively. Sugar binding leads to unquenching of Trp fluorescence in both mutants, a finding clearly consistent with opening of the periplasmic cavity. The pH dependence of Trp-245 unquenching exhibits a pK(a) of 8, typical for a His side chain interacting with an aromatic group. As estimated from stopped-flow studies, the rate of sugar-induced opening is approximately 100 s(-1). On the cytoplasmic side, Phe-140 (helix V) and Phe-334 (helix X) are located on opposite sides of a wide-open hydrophilic cavity. In precisely the opposite fashion from the periplasmic side, mutant Phe-140-->Trp/Phe-334-->His exhibits sugar-induced Trp quenching. Again, quenching is pH dependent (pK(a) = 8), but remarkably, the rate of sugar-induced quenching is only approximately 0.4 s(-1). The results provide yet another strong, independent line of evidence for the alternating access mechanism and demonstrate that the methodology described provides a sensitive probe to measure rates of conformational change in membrane transport proteins.
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Affiliation(s)
- Irina Smirnova
- Department of Physiology, University of California, Los Angeles, CA 90095-7327, USA
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192
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Smirnova I, Kasho V, Sugihara J, Choe JY, Kaback HR. Residues in the H+ translocation site define the pKa for sugar binding to LacY. Biochemistry 2009; 48:8852-60. [PMID: 19689129 DOI: 10.1021/bi9011918] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A remarkably high pKa of approximately 10.5 has been determined for sugar-binding affinity to the lactose permease of Escherichia coli (LacY), indicating that, under physiological conditions, substrate binds to fully protonated LacY. We have now systematically tested site-directed replacements for the residues involved in sugar binding, as well as H+ translocation and coupling, in order to determine which residues may be responsible for this alkaline pKa. Mutations in the sugar-binding site (Glu126, Trp151, Glu269) markedly decrease affinity for sugar but do not alter the pKa for binding. In contrast, replacements for residues involved in H+ translocation (Arg302, Tyr236, His322, Asp240, Glu325, Lys319) exhibit pKa values for sugar binding that are either shifted toward neutral pH or independent of pH. Values for the apparent dissociation constant for sugar binding (K(d)(app)) increase greatly for all mutants except neutral replacements for Glu325 or Lys319, which are characterized by remarkably high affinity sugar binding (i.e., low K(d)(app)) from pH 5.5 to pH 11. The pH dependence of the on- and off-rate constants for sugar binding measured directly by stopped-flow fluorometry implicates k(off) as a major factor for the affinity change at alkaline pH and confirms the effects of pH on K(d)(app) inferred from steady-state fluorometry. These results indicate that the high pKa for sugar binding by wild-type LacY cannot be ascribed to any single amino acid residue but appears to reside within a complex of residues involved in H+ translocation. There is structural evidence for water bound in this complex, and the water could be the site of protonation responsible for the pH dependence of sugar binding.
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Affiliation(s)
- Irina Smirnova
- Department of Physiology, University of California Los Angeles, Los Angeles, California 90095-7327, USA
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193
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Domoroshchina E, Kaurova I, Kuz'micheva G, Kudrenko E, Smirnova I, Rybakov V, Zaharko O, Cousson A. The crystal structure, substructure and properties of langatate. Acta Crystallogr A 2009. [DOI: 10.1107/s0108767309094744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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194
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Wille S, Schwarze M, Mokrushina L, Smirnova I, Schomäcker R, Arlt W. Reaktionen in mizellaren Systemen: Vorhersage von Verteilungskoeffizienten. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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195
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Ingram T, Bockemühl V, Wörmeyer K, Zetzl C, Antranikian G, Brunner G, Smirnova I. Umwandlung von Biomasse: Gewinnung von Pentosen und Ligninprodukten. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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196
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Irfan M, Seiler M, Smirnova I, Arlt W. Melt Dispersion Method: Die Entwicklung von Prozess und Formulierung. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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197
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Alnaief M, Cumana S, Smirnova I. Production of Biocompatible Aerogel Microparticles. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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198
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Buggert M, Cadena C, Mokrushina L, Smirnova I, Maginn EJ, Arlt W. COSMO-RS Calculations of Partition Coefficients: Different Tools for Conformation Search. Chem Eng Technol 2009. [DOI: 10.1002/ceat.200800654] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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199
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Mallepally RR, Smirnova I, Arlt W, Seiler M, Klee-Laquai SK, Hills G. Enzymatic degradation of hyperbranched polyesters. J Appl Polym Sci 2009. [DOI: 10.1002/app.29524] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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200
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