DOCSLIB.ORG

The Substrate Tolerance of Alcohol Oxidases

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Substrate Tolerance of Alcohol Oxidases Appl Microbiol Biotechnol (2015) 99:6617–6642 DOI 10.1007/s00253-015-6699-6 MINI-REVIEW The substrate tolerance of alcohol oxidases Mathias Pickl2 & Michael Fuchs2 & Silvia M. Glueck1,2 & Kurt Faber2 Received: 7 April 2015 /Revised: 10 May 2015 /Accepted: 15 May 2015 /Published online: 8 July 2015 # The Author(s) 2015. This article is published with open access at Springerlink.com Abstract Alcohols are a rich source of compounds from re- Introduction newable sources, but they have to be activated in order to allow the modification of their carbon backbone. The latter Oxidation represents a fundamental reaction in nature can be achieved via oxidation to the corresponding aldehydes (Hollmann et al. 2011; Turner 2011), and oxidases are a prom- or ketones. As an alternative to (thermodynamically inent subclass of redox enzymes, which use oxygen either as disfavoured) nicotinamide-dependent alcohol dehydroge- oxidant or as electron acceptor. This property made them par- nases, alcohol oxidases make use of molecular oxygen but ticularly attractive for the production of chemicals their application is under-represented in synthetic biotransfor- (Vennestrom et al. 2010). In this context, the oxidation of mations. In this review, the mechanism of copper-containing alcohols is an important transformation in synthetic chemistry, and flavoprotein alcohol oxidases is discussed in view of their which allows to introduce carbonyl groups, which represent ability to accept electronically activated or non-activated alco- excellent acceptors for C-, N-, O-andS-nucleophiles and hols and their propensity towards over-oxidation of aldehydes thereby allows the extension of a given carbon backbone. yielding carboxylic acids. In order to facilitate the selection of Consequently, a large number of protocols has been devel- the optimal enzyme for a given biocatalytic application, the oped, which depend on (i) transition metals in stoichiometric substrate tolerance of alcohol oxidases is compiled and (e.g. Cr, Mn) or catalytic amounts (e.g. Ru, Fe), (ii) metal-free discussed: Substrates are classified into groups (non-activated oxidations according to Swern or Pfitzner-Moffat (Pfitzner prim-andsec-alcohols; activated allylic, cinnamic and ben- and Moffatt 1963; Omura and Swern 1978), (iii) molecular zylic alcohols; hydroxy acids; sugar alcohols; nucleotide al- oxygen as oxidant (Tojo and Fernández 2006) and more re- cohols; sterols) together with suitable alcohol oxidases, their cently, (iv) organocatalysts, such as TEMPO (Wertz and microbial source, relative activities and (stereo)selectivities. Studer 2013). In a related fashion, alcohol oxidases convert primary and secondary alcohols to aldehydes and ketones, respectively. Keywords Oxidation Biocatalysis Alcohol oxidase During this reaction, molecular oxygen is reduced to hydro- . Substrate tolerance Flavoprotein Cu-containing oxidase gen peroxide. In order to avoid enzyme deactivation, a cata- lase is usually employed, particularly on preparative scale. For Electronic supplementary material The online version of this article (doi:10.1007/s00253-015-6699-6) contains supplementary material, screening purposes, a spectrophotometric assay based on which is available to authorized users. horse radish peroxidase (HRP) together with a suitable artifi- cial electron acceptor, such as 2,2′-azino-bis(3- * Kurt Faber ethylbenzthiazoline-6-sulfonic acid) (ABTS) may be [email protected] employed (Scheme 1). The ABTS-radical generated shifts its absorption maximum (Baron et al. 1994; Uwajima and Terada 1 Austrian Centre of Industrial Biotechnology (ACIB GmbH), 1980). Petersgasse 14, 8010 Graz, Austria Although cofactor-lacking oxidases are reported (Fetzner 2 Department of Chemistry, Organic & Bioorganic Chemistry, and Steiner 2010), commonly used alcohol oxidases depend University of Graz, Heinrichstrasse 28, A-8010 Graz, Austria on flavin (Macheroux et al. 2011; Dijkman et al. 2013)ora 6618 Appl Microbiol Biotechnol (2015) 99:6617–6642 OH O alcohol oxidase stabilised oxocarbenium cation, which upon expulsion of H+ R1 R2 R1 R2 furnishes the carboxylic acid. In contrast, hydride abstraction Catalase or 1 from the carbonyl form would lead to a highly unstable O2 H2O2 H2O + /2 O2 HRP/ABTS (hypothetical) acylium cation, which would be quenched by Scheme 1 Biocatalytic oxidation of alcohols using an alcohol oxidase a water molecule (Scheme 3). This mechanism for over-oxidation has been proposed for choline oxidase (CHO), whose natural role is the formation of metal (Cu) as a cofactor (Whittaker 2003), which mediates the N-trimethylammonium glycine (‘betaine’) from choline via electron transfer. In flavoprotein oxidases, the oxidation pro- the aldehyde hydrate through a two-step oxidation (Scheme 4) ceeds via two half reactions, where the alcohol is first oxidised (Rungsrisuriyachai and Gadda 2008). by a two-electron transfer during the reductive half reaction, The over-oxidation of alcohols to carboxylic acids has been yielding reduced flavin. The oxidised flavin is regenerated by observed not only for choline oxidase but also for other fla- a stepwise single-electron transfer via the oxidative half voprotein oxidases, such as alditol oxidase (AldO), aryl alco- reaction, which requires triplet oxygen, as it is a spin- hol oxidase (AAO), hydroxymethyl furfuryl oxidase forbidden reaction. Hence, di-oxygen acts as single-electron (HMFO), hexose oxidase (HOX, Dbv29), isoamyl alcohol −· acceptor and forms superoxide (O2 ), stabilised by a positive- oxidase (IAO) or short- and long-chain alcohol oxidases ly charged histidine residue (Dijkman et al. 2013; Wongnate (SCAOs, LCAOs). Labelling studies proved the existence of et al. 2014). Another single-electron transfer yields a covalent the aldehyde hydrate as intermediate (Van Hellemond et al. hydroperoxy flavin intermediate, which eliminates hydrogen 2009), and for AAO, which naturally oxidises benzylic alco- peroxide and re-forms oxidised flavin (Scheme 2) (Gadda hols, NMR studies revealed that the gem-diol intermediate 2012). The highly unstable C4a-hydroperoxyflavin intermedi- was favoured (Ferreira et al. 2010)(Scheme3). ate has only been detected for pyranose oxidase (P2O) Structurally, most of the flavoprotein oxidases either be- (Mattevi 2006; Chaiyen et al. 2012; Wongnate and Chaiyen long to the glucose-methanol-choline (GMC) oxidase or the 2013). vanillyl alcohol oxidase (VAO) family. Both families have a The oxidation of primary alcohols catalysed by flavopro- flavin present in the active site where the binding domain and tein oxidases does not necessarily stop at the aldehyde stage, the binding mode of the flavin differ. In case of VAO, the but may further proceed to the corresponding carboxylic acid. flavin is covalently linked to a histidine, cysteine or tyrosine This second oxidation step is mechanistically less investigat- residue, while in the GMC family, the majority of the enzymes ed, but it is obvious that the actual substrate is the aldehyde contain a dissociable flavin adenine dinucleotide (FAD) moi- hydrate (gem-diol), rather than its carbonyl form, because hy- ety. In P2O or CHO, a covalent linkage was found. The active dride abstraction from the former yields a doubly resonance- sites and consequently the substrate scope of these enzymes Scheme 2 Catalytic cycle of flavin-containing alcohol oxidases Appl Microbiol Biotechnol (2015) 99:6617–6642 6619 O - [H-] OH O RC RCO RCO H2O H R1 R2 R1 R2 acylium cation (not formed) H+ carbonyl form reductive half reaction O RC H O + Cu2+ O Tyr Cu+ O Tyr 2 H OH H S S OH - OH - [H ] OH OH Cys + Cys RCOH RC RC RC H O OH OH H2O2 2 H OH hydrate form resonance-stabilised carbenium ion oxidative half reaction Scheme 3 Aldehyde oxidation via the hydrate intermediate Cu2+ O Tyr Cu2+ O Tyr O H HO S show high variance (Fraaije et al. 1998a; Kiess et al. 1998; S O OH Cys Leferink et al. 2008; Dijkman et al. 2013). Cys Another redox cofactor found in alcohol oxidases, such as Scheme 5 Catalytic cycle of copper-containing oxidases galactose oxidase (GOase), is the transition metal copper, whose role in catalysis is well described in several reviews size and/or polarity (Turner 2011). In fungi, extracellular al- (Ridge et al. 2008; Guengerich 2013). Since only a single cohol oxidases produce hydrogen peroxide (needed for lignin copper(I) ion is found in the active site, it seems surprising degradation by peroxidases) by oxidation of cinnamyl alco- that a two-electron transfer can occur. Detailed investigations hols (e.g. coniferyl, coumaryl and sinapyl alcohol). Further- revealed that the latter proceeds via two consecutive single- more, hydrogen peroxide acts as antibiotic in the rhizosphere electron transfer steps. Thus, abstraction of the first electron to protect roots (Monti et al. 2011). As an alternative to alco- by Cu2+ yields Cu+, which transfers its electron onto a tyrosine hol oxidases, NAD(P)+-dependent alcohol dehydrogenases residue, which forms a transient radical anion (Monti et al. provide a well-investigated enzyme platform for the oxidation 2011). The latter is stabilised by a rare covalent thioether of prim-andsec-alcohol functionalities. Although these en- bridge with an adjacent cysteine (Ito et al. 1991). The second zymes are more abundant than alcohol oxidases, the equilib- electron transfer yields a Cu+-tyrosine radical. From this, ox- rium for oxidation is strongly disfavored but can be overcome ygen accepts two electrons (Wang 1998; Whittaker 2003) by NAD(P)+ recycling (Hollmann et al. 2011).
Load more

Recommended publications
  • Biotransformation of Vanillin Into Vanillyl Alcohol by a Novel Strain of Cystobasidium Laryngis Isolated from Decaying Wood
    Rönnander et al. AMB Expr (2018) 8:137 https://doi.org/10.1186/s13568-018-0666-4 ORIGINAL ARTICLE Open Access Biotransformation of vanillin into vanillyl alcohol by a novel strain of Cystobasidium laryngis isolated from decaying wood Jonas Rönnander1* , Joel Ljunggren2 , Erik Hedenström2 and Sandra Ann Ingela Wright1* Abstract Vanillin is an aromatic aldehyde found as a component of lignocellulosic material, and in the cured pods of orchi- daceae plants. Like other phenolic substances, vanillin has antimicrobial activity and can be extracted from lignin either by a thermo-chemical process or through microbial degradation. Vanillin, can serve as a model monomer in biodegradation studies of lignin. In the present study, a yeast isolated from decaying wood on the Faroe Islands, was identifed as Cystobasidium laryngis strain FMYD002, based on internal transcribed spacer sequence analysis. It dem- onstrated the ability to convert vanillin to vanillyl alcohol, as detected by ultra-high performance liquid chromatogra- phy–quadrupole-time-of-fight. Structural analysis of vanillyl alcohol was carried out by using gas chromatography– mass spectrometry and 1H NMR spectroscopy, and further verifed by synthesis. The reduction of vanillin to vanillyl alcohol has been documented for only a few species of fungi. However, to our knowledge, this biotransformation has not yet been reported for basidiomycetous yeast species, nor for any representative of the subphylum Pucciniomyco- tina. The biotransformation capability of the present strain might prove useful in the industrial utilisation of lignocel- lulosic residues. Keywords: Vanillin, Cystobasidium, Bioconversion, Biodegradation, Cystobasidiomycetes, Rhodotorula Introduction an aromatic aldehyde derived from the guaiacyl subunit Lignin is an abundant polymer in nature, a natural aro- of lignin (Brebu and Vasile 2010; Fache et al.
    [Show full text]
  • Vanillyl Alcohol Dehydrogenase) from Rhodopseudomonas Acidophila M402 Purification, Identification of Reaction Product and Substrate Specificity
    Agric. Biol Chem., 47 (10), 2173~2183, 1983 2173 A NewDye-Linked Alcohol Dehydrogenase (Vanillyl Alcohol Dehydrogenase) from Rhodopseudomonas acidophila M402 Purification, Identification of Reaction Product and Substrate Specificity Kei Yamanaka and Yasutaka Tsuyuki Institute of Applied Biochemistry, and Graduate School of Master's Program in Environmental Sciences, The University of Tsukuba, Sakura-mura, Niihari-gun, Ibaraki 305, Japan Received October 19, 1982 A new dye-linked alcohol dehydrogenase (vanillyl alcohol dehydrogenase) was purified to homogeneity from cells of Rhodopseudomonas acidophila strain M402 grown aerobically on vanillyl alcohol. The reaction product from vanillyl alcohol was identified as vanillin as judged by its melting point, elemental analysis and IR, mass and NMR spectra. The molecular weight of the enzyme was estimated to be approximately 72,000 as determined by gel filtration and the isoelectric point was pH 6.01. The most characteristic feature of this enzyme is its wide substrate specificity range. The enzyme catalyzes the dehydrogenation of various aromatic and aliphatic alcohols and aldehydes with phenazine methosulfate as electron acceptor. The active substrates of this enzyme are as follows: Vanillyl alcohol, benzyl alcohol, cinnamyl alcohol, 2-phenylethanol, 2-phenoxyethanol, aliphatic alcohols of C2 to G8, rr<m?-cinnamaldehyde, formaldehyde, propionaldehyde and butyraldehyde. The highest activities were obtained with vanillyl alcohol, rc-propanol and ^-butanol at the same level. The apparent Kmvalues were as follows: 112/zm for vanillyl alcohol, 7/jm for benzyl alcohol, 180/im for «-propanol, 14^m for #-butanol, 20/zm for 2-phenoxyethanol, 12/iM for 2-phenylethanol and 105 /zm for butyraldehyde. These activities were confirmed to be catalyzed by a single enzyme by activity staining on polyacrylamide gels.
    [Show full text]
  • Hereditary Galactokinase Deficiency J
    Arch Dis Child: first published as 10.1136/adc.46.248.465 on 1 August 1971. Downloaded from Alrchives of Disease in Childhood, 1971, 46, 465. Hereditary Galactokinase Deficiency J. G. H. COOK, N. A. DON, and TREVOR P. MANN From the Royal Alexandra Hospital for Sick Children, Brighton, Sussex Cook, J. G. H., Don, N. A., and Mann, T. P. (1971). Archives of Disease in Childhood, 46, 465. Hereditary galactokinase deficiency. A baby with galactokinase deficiency, a recessive inborn error of galactose metabolism, is des- cribed. The case is exceptional in that there was no evidence of gypsy blood in the family concerned. The investigation of neonatal hyperbilirubinaemia led to the discovery of galactosuria. As noted by others, the paucity of presenting features makes early diagnosis difficult, and detection by biochemical screening seems desirable. Cataract formation, of early onset, appears to be the only severe persisting complication and may be due to the biosynthesis and accumulation of galactitol in the lens. Ophthalmic surgeons need to be aware of this enzyme defect, because with early diagnosis and dietary treatment these lens changes should be reversible. Galactokinase catalyses the conversion of galac- and galactose diabetes had been made in this tose to galactose-l-phosphate, the first of three patient (Fanconi, 1933). In adulthood he was steps in the pathway by which galactose is converted found to have glycosuria as well as galactosuria, and copyright. to glucose (Fig.). an unexpectedly high level of urinary galactitol was detected. He was of average intelligence, and his handicaps, apart from poor vision, appeared to be (1) Galactose Gackinase Galactose-I-phosphate due to neurofibromatosis.
    [Show full text]
  • Adaptive Laboratory Evolution Enhances Methanol Tolerance and Conversion in Engineered Corynebacterium Glutamicum
    ARTICLE https://doi.org/10.1038/s42003-020-0954-9 OPEN Adaptive laboratory evolution enhances methanol tolerance and conversion in engineered Corynebacterium glutamicum Yu Wang 1, Liwen Fan1,2, Philibert Tuyishime1, Jiao Liu1, Kun Zhang1,3, Ning Gao1,3, Zhihui Zhang1,3, ✉ ✉ 1234567890():,; Xiaomeng Ni1, Jinhui Feng1, Qianqian Yuan1, Hongwu Ma1, Ping Zheng1,2,3 , Jibin Sun1,3 & Yanhe Ma1 Synthetic methylotrophy has recently been intensively studied to achieve methanol-based biomanufacturing of fuels and chemicals. However, attempts to engineer platform micro- organisms to utilize methanol mainly focus on enzyme and pathway engineering. Herein, we enhanced methanol bioconversion of synthetic methylotrophs by improving cellular tolerance to methanol. A previously engineered methanol-dependent Corynebacterium glutamicum is subjected to adaptive laboratory evolution with elevated methanol content. Unexpectedly, the evolved strain not only tolerates higher concentrations of methanol but also shows improved growth and methanol utilization. Transcriptome analysis suggests increased methanol con- centrations rebalance methylotrophic metabolism by down-regulating glycolysis and up- regulating amino acid biosynthesis, oxidative phosphorylation, ribosome biosynthesis, and parts of TCA cycle. Mutations in the O-acetyl-L-homoserine sulfhydrylase Cgl0653 catalyzing formation of L-methionine analog from methanol and methanol-induced membrane-bound transporter Cgl0833 are proven crucial for methanol tolerance. This study demonstrates the importance of
    [Show full text]
  • In Silico Screening of Sugar Alcohol Compounds to Inhibit Viral Matrix Protein VP40 of Ebola Virus
    Molecular Biology Reports (2019) 46:3315–3324 https://doi.org/10.1007/s11033-019-04792-w ORIGINAL ARTICLE In silico screening of sugar alcohol compounds to inhibit viral matrix protein VP40 of Ebola virus Nagasundaram Nagarajan1 · Edward K. Y. Yapp2 · Nguyen Quoc Khanh Le1 · Hui‑Yuan Yeh1 Received: 28 December 2018 / Accepted: 28 March 2019 / Published online: 13 April 2019 © Springer Nature B.V. 2019 Abstract Ebola virus is a virulent pathogen that causes highly lethal hemorrhagic fever in human and non-human species. The rapid growth of this virus infection has made the scenario increasingly complicated to control the disease. Receptor viral matrix protein (VP40) is highly responsible for the replication and budding of progeny virus. The binding of RNA to VP40 could be the crucial factor for the successful lifecycle of the Ebola virus. In this study, we aimed to identify the potential drug that could inhibit VP40. Sugar alcohols were enrich with antiviral properties used to inhibit VP40. Virtual screening analysis was perform for the 48 sugar alcohol compounds, of which the following three compounds show the best binding afnity: Sorbitol, Mannitol and Galactitol. To understand the perfect binding orientation and the strength of non-bonded interactions, individual molecular docking studies were perform for the best hits. Further molecular dynamics studies were conduct to analyze the efcacy between the protein–ligand complexes and it was identify that Sorbitol obtains the highest efcacy. The best-screened compounds obtained drug-like property and were less toxic, which could be use as a potential lead compound to develop anti-Ebola drugs.
    [Show full text]
  • WO 2019/079361 Al 25 April 2019 (25.04.2019) W 1P O PCT
    (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization I International Bureau (10) International Publication Number (43) International Publication Date WO 2019/079361 Al 25 April 2019 (25.04.2019) W 1P O PCT (51) International Patent Classification: CA, CH, CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, DO, C12Q 1/68 (2018.01) A61P 31/18 (2006.01) DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, C12Q 1/70 (2006.01) HR, HU, ID, IL, IN, IR, IS, JO, JP, KE, KG, KH, KN, KP, KR, KW, KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME, (21) International Application Number: MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, PCT/US2018/056167 OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, (22) International Filing Date: SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, 16 October 2018 (16. 10.2018) TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (25) Filing Language: English (84) Designated States (unless otherwise indicated, for every kind of regional protection available): ARIPO (BW, GH, (26) Publication Language: English GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, TZ, (30) Priority Data: UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ, 62/573,025 16 October 2017 (16. 10.2017) US TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, ΓΕ , IS, IT, LT, LU, LV, (71) Applicant: MASSACHUSETTS INSTITUTE OF MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TECHNOLOGY [US/US]; 77 Massachusetts Avenue, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, Cambridge, Massachusetts 02139 (US).
    [Show full text]
  • Hydrodeoxygenation of Lignin Model Compounds Over a Copper Chromite
    Applied Catalysis A: General 447–448 (2012) 144–150 Contents lists available at SciVerse ScienceDirect Applied Catalysis A: General jo urnal homepage: www.elsevier.com/locate/apcata Hydrodeoxygenation of lignin model compounds over a copper chromite catalyst ∗ Keenan L. Deutsch, Brent H. Shanks Department of Chemical & Biological Engineering, Iowa State University, Ames, IA 50011, USA a r t i c l e i n f o a b s t r a c t Article history: The hydrodeoxygenation of benzyl alcohol, phenol, anisole, o-cresol, catechol, guaiacol, and vanillyl alco- ◦ Received 19 April 2012 hol were carried out from 150 to 275 C at 50 bar H2 with a CuCr2O4·CuO catalyst in a decalin solvent. Received in revised form 5 September 2012 The hydroxymethyl group of benzyl alcohol was found to be highly reactive towards hydrogenolysis Accepted 13 September 2012 to form toluene. Demethoxylation of anisole to form benzene was found to be the primary reaction Available online 8 October 2012 pathway in contrast to demethylation and transalkylation reactions, which are more prevalent for con- ventional hydrotreating catalysts. The hydroxyl group of phenol strongly activated the aromatic ring Keywords: towards hydrogenation forming cyclohexanol which was subsequently dehydrated and hydrogenated Hydrogenolysis Hydrodeoxygenation to form cyclohexane. Reaction networks of increasing complexity were devised for the major functional groups and integrated to describe the most complex molecule studied, vanillyl alcohol. Copper catalyst Lignin © 2012 Elsevier B.V. All rights reserved. Bio-oil upgrading Copper chromite 1. Introduction liquid product from fast pyrolysis [6]. The lignin-derived compo- nents of biomass are commonly used as model compounds for The utilization of biomass to produce fuels and chemicals is a HDO because they possess the aromaticity that is important to topic of increasing importance as petroleum prices rise and reserves maintain to minimize hydrogen consumption [2].
    [Show full text]
  • The Institute of Paper Chemistry
    The Institute of Paper Chemistry Appleton, Wisconsin Doctor's Dissertation Reaction Products of Lignin Model Compounds and Sodium Hydrosulfide Thomas G. Zentner June, 1953 A STUDY OF THE REACTION PRODUCTS OF LIGNIN MODEL COMPOUNDS AND SODIUM HYDROSULFIDE A thesis submitted by Thomas G. Zentner B.S. 1948, Texas A & M College M.S. 1950, Lawrence College in partial fulfillment of the requirements of The Institute of Paper Chemistry for the degree of Doctor of Philosophy from Lawrence College, Appleton, Wisconsin June, 1952 TABLE OF CONTENTS INTRODUCTION 1 HISTORICAL REVIEW 2 PRESENTATION OF THE PROBLEM 8 EXPERIMENTAL PROCEDURES 10 Synthesis of Compounds 10 Synthesis of 1-(4-Hydroxy-3-methoxyphenyl)-l-propanol 10 Synthesis of 1-(4-Benzoxy-3-methoxyphenyl)-l-propanol 11 Reaction of 1-(4-Benzoxy-3-methoxyphenyl) l-propanol with Benzyl Chloride 12 Synthesis of Propiovanillone 14 Synthesis of (-(4-Acetyl-2-methoxyphenoxy)acetovanillone 17 Attempted Synthesis of a-(2-Methoxy-4-methylphehoxy)- propiovanillone 17 Attempted Synthesis of 4-[l-(2-Methoxy-4-methylphenoxy)- l-propyl]guaiacol 21 Synthesis of 2t,4-Dihydroxy-3-methoxychalcone 23 Synthesis of 4,4'-Dihydroxy-3,3 -dimethoxychalcone 24 Synthesis of 4-Propionylpyrocatechol 24 Synthesis of Bis[l-(4-hydroxy-3-methoxyphenyl)-1- propyl] Disulfide 26 Reaction of Isolated Native Lignin with Potassium Hydrosulfide 27 Sodium Hydrosulfide Cooks 28 Cooking Liquor 28 General Procedures 30 Propiovanillone' 32 iii 2 ,4-Dihydroxy-3-methoxychalcone 34 4,4'-Dihydroxy-3,3 '-methoxychalcohe 37 4'-Hydroxy-3t-methoxyflavanone 39 2-Vanillylidene-3-coumaranone 41 Vanillin 44 G- (4-Acetyl-2-methoxyphenoxy)acetovanillone 45 1-(4-Hydroxy-3-methoxyphenyl)-1-propanol 49 DISCUSSION 58 SUMMARY AND CONCLUSIONS 69 LITERATURE CITED 71 INTRODUCTION Although the kraft process has been in use for many years, there is no sound explanation of the role played by the sulfide ion in the cook.
    [Show full text]
  • Engineering Alcohol Oxidases for Substrate Scope and Their Application in Flow and Cascade Biocatalysis
    ENGINEERING ALCOHOL OXIDASES FOR SUBSTRATE SCOPE AND THEIR APPLICATION IN FLOW AND CASCADE BIOCATALYSIS Rachel Heath, University of Manchester [email protected] Matthew Thompson, EnginZyme Jeremy Ramsden, University of Manchester Sebastian Cosgrove, University of Manchester William Finnigan, University of Manchester Nicholas Turner, University of Manchester Key Words: oxidation, primary alcohol, secondary alcohol, high-throughput screening, thermostability Alcohol oxidases have significant advantages over alcohol dehydrogenases (ADHs) for biocatalytic oxidation of alcohols: they don’t require addition of (expensive) nicotinamide cofactors (or a recycling system for cofactor regeneration) and the catalytic reaction is irreversible. Although alcohol oxidases generate hydrogen peroxide when they turn over, this issue can be alleviated by addition of catalase, which, not only removes the peroxide, but also creates more oxygen for cofactor regeneration. Alcohol oxidases are perceived to have a limited substrate scope preventing their wider use in synthesis. Thus, we present the engineering of two alcohol oxidases for increased substrate scope, one for the selective oxidation of primary alcohols and one for secondary alcohol oxidation. Arthrobacter chlorophenolicus choline oxidase and Streptomyces hygroscopicus cholesterol oxidase were selected as the primary and secondary alcohol oxidase, respectively. Examination of crystal structures of homologous alcohol oxidases revealed positions in the active site and entrance channel to target for saturation mutagenesis. Libraries were screened using a high-throughput assay based on the detection of hydrogen peroxide using hexanol as the substrate for evolution of choline oxidase and cyclohexanol for evolution of cholesterol oxidase. Mutations from positive hits were combined and, in these cases, resulted in variants with further improvements in both kcat and conversion to the carbonyl in biotransformations.
    [Show full text]
  • Solarbio Catalogue with PRICES
    CAS Name Grade Purity Biochemical Reagent Biochemical Reagent 75621-03-3 C8390-1 3-((3-Cholamidopropyl)dimethylammonium)-1-propanesulfonateCHAPS Ultra Pure Grade 1g 75621-03-3 C8390-5 3-((3-Cholamidopropyl)dimethylammonium)-1-propanesulfonateCHAPS 5g 57-09-0 C8440-25 Cetyl-trimethyl Ammonium Bromide CTAB High Pure Grade ≥99.0% 25g 57-09-0 C8440-100 Cetyl-trimethyl Ammonium Bromide CTAB High Pure Grade ≥99.0% 100g 57-09-0 C8440-500 Cetyl-trimethyl Ammonium Bromide CTAB High Pure Grade ≥99.0% 500g E1170-100 0.5M EDTA (PH8.0) 100ml E1170-500 0.5M EDTA (PH8.0) 500ml 6381-92-6 E8030-100 EDTA disodium salt dihydrate EDTA Na2 Biotechnology Grade ≥99.0% 100g 6381-92-6 E8030-500 EDTA disodium salt dihydrate EDTA Na2 Biotechnology Grade ≥99.0% 500g 6381-92-6 E8030-1000 EDTA disodium salt dihydrate EDTA Na2 Biotechnology Grade ≥99.0% 1kg 6381-92-6 E8030-5000 EDTA disodium salt dihydrate EDTA Na2 Biotechnology Grade ≥99.0% 5kg 60-00-4 E8040-100 Ethylenediaminetetraacetic acid EDTA Ultra Pure Grade ≥99.5% 100g 60-00-4 E8040-500 Ethylenediaminetetraacetic acid EDTA Ultra Pure Grade ≥99.5% 500g 60-00-4 E8040-1000 Ethylenediaminetetraacetic acid EDTA Ultra Pure Grade ≥99.5% 1kg 67-42-5 E8050-5 Ethylene glycol-bis(2-aminoethylether)-N,N,NEGTA′,N′-tetraacetic acid Ultra Pure Grade ≥97.0% 5g 67-42-5 E8050-10 Ethylene glycol-bis(2-aminoethylether)-N,N,NEGTA′,N′-tetraacetic acid Ultra Pure Grade ≥97.0% 10g 50-01-1 G8070-100 Guanidine Hydrochloride Guanidine HCl ≥98.0%(AT) 100g 50-01-1 G8070-500 Guanidine Hydrochloride Guanidine HCl ≥98.0%(AT) 500g 56-81-5
    [Show full text]
  • Hemicellulose Arabinogalactan Hydrolytic Hydrogenation Over Ru-Modified H-USY Zeolites
    Research Collection Journal Article Hemicellulose arabinogalactan hydrolytic hydrogenation over Ru-modified H-USY zeolites Author(s): Murzin, Dmitry; Kusema, Bright; Murzina, Elena V.; Aho, Atte; Tokarev, Anton; Boymirzaev, Azamat S.; Wärnå, Johan; Dapsens, Pierre Y.; Mondelli, Cecilia; Pérez-Ramírez, Javier; Salmi, Tapio Publication Date: 2015-10 Permanent Link: https://doi.org/10.3929/ethz-a-010792434 Originally published in: Journal of Catalysis 330, http://doi.org/10.1016/j.jcat.2015.06.022 Rights / License: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library Hemicellulose arabinogalactan hydrolytic hydrogenation over Ru-modified H-USY zeolites Dmitry Yu. Murzin1*, Bright Kusema2, Elena V. Murzina1, Atte Aho1, Anton Tokarev1, Azamat S. Boymirzaev3, Johan Wärnå1,4, Pierre Y. Dapsens2, Cecilia Mondelli2, Javier Pérez-Ramírez2, Tapio Salmi1 1Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Department of Chemical Engineering, Åbo Akademi University, FI-20500 Åbo/Turku, Finland, E-mail: [email protected] 2Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, CH-8093 Zurich, Switzerland 3Namangan Institute of Engineering and Technology, Department of Chemical Technology, Namangan, 160115, Uzbekistan 4University of Umeå, Umeä, Sweden ABSTRACT The hydrolytic hydrogenation of hemicellulose arabinogalactan was investigated in the presence of protonic and Ru (1-5 wt.%)-modified USY zeolites (Si/Al ratio = 15 and 30). The use of the purely acidic materials was effective in depolymerizing the macromolecule into free sugars. While the latter partly dehydrated into 5- hydroxymethylfurfural and furfural, the generation of high molecular-weight compounds (aggregates of sugars and humins) was not favored, in contrast to previous evidences over beta zeolites.
    [Show full text]
  • Sugar Alcohols a Sugar Alcohol Is a Kind of Alcohol Prepared from Sugars
    Sweeteners, Good, Bad, or Something even Worse. (Part 8) These are Low calorie sweeteners - not non-calorie sweeteners Sugar Alcohols A sugar alcohol is a kind of alcohol prepared from sugars. These organic compounds are a class of polyols, also called polyhydric alcohol, polyalcohol, or glycitol. They are white, water-soluble solids that occur naturally and are used widely in the food industry as thickeners and sweeteners. In commercial foodstuffs, sugar alcohols are commonly used in place of table sugar (sucrose), often in combination with high intensity artificial sweeteners to counter the low sweetness of the sugar alcohols. Unlike sugars, sugar alcohols do not contribute to the formation of tooth cavities. Common Sugar Alcohols Arabitol, Erythritol, Ethylene glycol, Fucitol, Galactitol, Glycerol, Hydrogenated Starch – Hydrolysate (HSH), Iditol, Inositol, Isomalt, Lactitol, Maltitol, Maltotetraitol, Maltotriitol, Mannitol, Methanol, Polyglycitol, Polydextrose, Ribitol, Sorbitol, Threitol, Volemitol, Xylitol, Of these, xylitol is perhaps the most popular due to its similarity to sucrose in visual appearance and sweetness. Sugar alcohols do not contribute to tooth decay. However, consumption of sugar alcohols does affect blood sugar levels, although less than that of "regular" sugar (sucrose). Sugar alcohols may also cause bloating and diarrhea when consumed in excessive amounts. Erythritol Also labeled as: Sugar alcohol Zerose ZSweet Erythritol is a sugar alcohol (or polyol) that has been approved for use as a food additive in the United States and throughout much of the world. It was discovered in 1848 by British chemist John Stenhouse. It occurs naturally in some fruits and fermented foods. At the industrial level, it is produced from glucose by fermentation with a yeast, Moniliella pollinis.
    [Show full text]