DOCSLIB.ORG

Trehalose and Carbon Partitioning in Sugarcane

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Trehalose and Carbon Partitioning in Sugarcane TREHALOSE AND CARBON PARTITIONING IN SUGARCANE Susan Bosch Dissertation presented for the Degree of Doctor of Philosophy (Plant Biotechnology) at the University of Stellenbosch Promoter: Prof. F.C. Botha Institute for Plant Biotechnology and South African Sugar Research Institute Co-Promoter: Prof. J.M. Rohwer Department of Biochemistry December 2005 i Declaration I, the undersigned, hereby declare that the work contained in this dissertation is my own original work and that I have not previously in its entirety or in part submitted it at any university for a degree. Signature: ……………………….. Date: ……………………….. ii ABSTRACT The current understanding of the regulation of sucrose accumulation is still incomplete even though many scientists have investigated this subject. Components of trehalose metabolism have been implicated in the regulation of carbon flux in bacteria, yeast and more recently in plants. With a view to placing trehalose metabolism in the context of cytosolic sugarcane sucrose metabolism and carbon partitioning we have investigated the metabolites, transcripts and enzymes involved in this branch of carbohydrate metabolism in sugarcane internodal tissues. Sugarcane internodal trehalose levels varied between 0.31 ± 0.09 and 3.91 ± 0.99 nmol.g-1 fresh weight (FW). From statistical analysis of the metabolite profile it would appear that trehalose does not directly affect sucrose accumulation, although this does not preclude involvement of trehalose- 6-phosphate in the regulation of carbon partitioning. The metabolite data generated in this study demanded further investigation into the enzymes (and their transcripts) responsible for trehalose metabolism. Trehalose is synthesised in a two step process by the enzymes trehalose-6-phosphate synthase (EC 2.4.1.15, TPS) and trehalose-6-phosphate phosphatase (EC 3.1.3.12, TPP), and degraded by trehalase (EC 3.2.1.28). Two novel sugarcane partial cDNAs that coded for trehalase (tre) and actin (required for normalisation in profiling experiments) were isolated and used along with partial transcripts for TPS and TPP to determine transcript levels in different tissue- and genotypes. A putative full-length SugTPS cDNA was isolated and characterised. Enzyme activities for TPS, TPP and trehalase were measured at levels of 2.7 nmol.min-1.mg-1protein, 8.5 nmol.min-1.mg-1protein and 6.2 nmol.min-1.mg-1protein respectively, from young internodal protein extracts of sugarcane, variety N19. TPP enzyme activity and transcript levels were higher in S. spontaneum than Saccharum interspecific hybrids. Kinetic analysis of TPP and trehalase activities were performed with the purpose of providing parameters for an in silico kinetic model of trehalose and sucrose metabolism. Three isoforms of TPP were identified and desingated TPPAI, TPPAII and TPPB. Both TPPA isoforms had pH optima of 6.0, and TPPB of pH 6.5. Apparent Km values were determined as 0.447 ± 0.007 mM for TPPAI, 13.82 ± 1.98 mM for TPPAII and 1.387 ± 0.18 mM for TPPB. Partial purification and characterisation of trehalase demonstrated dual pH optima of 3.5 and 6.0, with Km values between 0.345 and 0.375 mM. These data were used as the basis for a kinetic model of trehalose metabolism. A previously described kinetic model of cytosolic sucrose metabolism has been expanded to include the trehalose pathway (TPS, TPP and trehalase). The aim was to supplement the iii available information on cytosolic metabolism in sugarcane storage parenchyma, identify points of control between sucrose and trehalose metabolism, and provide a platform from which further experimental and in silico modelling can be launched. The model predicted trehalose in the same order of magnitude as those determined in the metabolite profiling experiments. The majority of control of flux over the trehalose pathway resided in the TPS step, with flux control coefficients > 70% of the total pathway. Incorporation of the trehalose branch into the original sucrose model showed that reactions from the original model significantly affected the steady-state attributes of the trehalose pathway. Due to the relatively low flux through the trehalose branch of the expanded model, complete recycling of trehalose, and the lack of allosteric regulation by trehalose-6-phosphate or trehalose on any of the reactions from the original sucrose model, incorporation of the trehalose branch had no significant effect on either steady-state cytosolic sucrose concentration or flux of sucrose into the vacuole. The expanded model affords a basis from which to further investigate trehalose metabolism in the context of plant sucrose accumulation. iv OPSOMMING Die proses van sukrose akkumulering word nie volledig verstaan nie, ten spyte van uitgebreide navorsing oor hierdie onderwerp. Aspekte van trehalose-metabolisme is al geïmpliseer in die regulering van koolstofverdeling in bakterieë, giste en meer onlangs in plante. Teen die agtergrond van sitosoliese sukrose-metabolisme en koolstofverdeling in suikerriet, het ons trehalose-metabolisme ondersoek deur die metaboliete, transkripte en ensieme te bestudeer wat by hierdie gedeelte van koolhidraatmetabolisme in suikerriet betrokke is. Suikerrietstingel trehalose-vlakke het tussen 0.31 ± 0.09 en 3.91 ± 0.99 nmol.g-1 vars massa gewissel. Statistiese analise van die metabolietprofiel dui aan dat trehalose nie sukrose- akkumulering direk beïnvloed nie. Die betrokkenheid van trehalose-6-fosfaat by die regulering van koolstofverdeling kan egter nie uitgesluit word nie. Die analise van metabolietdata het vereis dat verdere ondersoek gedoen word op die ensieme wat verantwoordelik is vir trehalose metabolisme en op hulle transkripte. Trehalose word gesintetiseer in 'n twee-stap proses deur die ensieme trehalose-6-fosfaat sintase (EC 2.4..1.14, TPS) en trehalose-6-fosfaat fosfatase (EC 3.1.3.12, TPP), en word afgebreek deur trehalase (EC 3.2.1.28). Twee nuwe suikerriet geen-fragmente wat kodeer vir trehalase (tre) en aktien (benodig vir normalisering in uitdrukkings-eksperimente) is geïsoleer en saam met geen- fragmente vir TPS en TPP gebruik om transkripsievlakke in verskillende weefsel- en genotiepes te bepaal. 'n Kandidaat vollengte SugTPS geenfragment is geïsoleer en gekarakteriseer. Ensiemaktiwiteite vir TPS, TPP en trehalase, gemeet van jong stingel-proteïenekstrakte uit suikeriet variëteit N19, is 2.7 nmol.min-1.mg-1proteïen, 8.5 nmol.min-1.mg-1 proteïen en 6.2 nmol.min-1.mg-1 proteïen onderskeidelik. TPP ensiemaktiwiteit en transkripvlakke was hoër in Saccharum spontaneum as Saccharum interspesifieke hibriede. TPP en trehalase aktiwiteite is kineties geanaliseer met die doel om data vir 'n in silico kinetiese model van trehalose en sukrose metabolisme te voorsien. Drie isovorme van TPP is geïdentifiseer en TPPAI, TPPAII en TPPB genoem. Beide TPPA-isovorme het pH-optima van 6.0 gehad, en TPPB ‘n optimum van pH 6.5. Km waardes is bepaal as 0.447 ± 0.007 mM vir TPPAI, 13.82 ± 1.98 mM vir TPPAII en 1.387 ± 0.18 mM vir TPPB. Gedeeltelike suiwering en karakterisering van trehalase het 'n tweevoudige pH-optimum van 3.5 en 6.0 getoon, met Km waardes tussen 0.345 en 0.375 mM. Hierdie data is gebruik as die basis vir 'n kinetiese model van trehalose metabolisme. 'n Voorheen beskrewe kinetiese model van sitosoliese sukrose metabolisme is aldus uitgebrei (met TPS, TPP en trehalase) om die trehalose-pad in te sluit. Die doel was om die inligting wat tans beskikbaar is oor sitosoliese sukrose-metabolisme in bergingsweefsel van suikerriet aan te vul, v punte van beheer tussen sukrose en trehalose-metabolisme te identifiseer, en om 'n platform te skep waarvandaan verdere eksperimentele werk en in silico modellering geloods kan word. Die model het trehalose vlakke van dieselfde grootte-orde voorspel as dié wat eksperimenteel bepaal is. Die grootste beheer van fluksie deur die trehalose-pad is gesetel in die TPS stap, met 'n fluksie-kontrole-koëffisiënt > 70% van die totale pad. Inkorporering van die trehalose-tak in die oorspronklike sukrose-model het getoon dat die reaksies van die oorspronklike model 'n beduidende effek op die bestendige-toestand-eienskappe van die trehalose-pad uitoefen. As gevolg van die relatiewe lae fluksie deur die trehalose-tak van die uitgebreide model, die totale herwinning van glukose na trehalose degradasie, en die gebrek aan allosteriese regulering deur trehalose-6-fosfaat of trehalose op enige van die reaksies in die oorspronklike model, het inkorporering van die trehalose-tak geen beduidende effek op die bestendige-toestand van òf sitosoliese sukrosekonsentrasie òf die fluksie van sukrose na die vakuool gehad nie. Die uitgebreide model skep 'n basis vir verdere navorsing oor trehalose-metabolisme in die konteks van plant sukrose-akkumulering. vi FOR MY FATHER vii ACKNOWLEDGEMENTS I would like to thank both Dr. F.C. Botha and Prof J.M. Rohwer for supervision of this study. Frikkie, your input in both my life and this project will never be forgotten. I have learnt so much from you and feel privileged to have been your student. Johann, your guidance has opened a whole new side of biology to me- thank you for your infectious enthusiasm, patience and hard work. Thank you to Hennie Groenewald, Jens Kossmann and James Lloyd for consistently having an open-office-door policy for my many questions. To Mauritz Venter and Wolfgang Schäfer, thank you both for your willingness to help at all times and for the many useful discussions. Gratitude is expressed to Johan Thevelein and Patrick van Dijck who afforded me the opportunity of researching at the laboratory for Molecular Cell Biology, Katolieke Universiteit, Leuven, Belgium. Special thanks to Jean Mackenzie of the Central Analytical NMR facility (University of Stellenbosch) for help with both experiments and data processing from the NMR work. Financial support is gratefully acknowledged from the National Research Foundation, the South African Sugar Research Institute, the Bilateral SA-Belgian assoc., the Harry Crossley Trust, and the University of Stellenbosch. The support and love of my husband made the last years in the lab possible.
Load more

Recommended publications
  • Ii- Carbohydrates of Biological Importance
    Carbohydrates of Biological Importance 9 II- CARBOHYDRATES OF BIOLOGICAL IMPORTANCE ILOs: By the end of the course, the student should be able to: 1. Define carbohydrates and list their classification. 2. Recognize the structure and functions of monosaccharides. 3. Identify the various chemical and physical properties that distinguish monosaccharides. 4. List the important monosaccharides and their derivatives and point out their importance. 5. List the important disaccharides, recognize their structure and mention their importance. 6. Define glycosides and mention biologically important examples. 7. State examples of homopolysaccharides and describe their structure and functions. 8. Classify glycosaminoglycans, mention their constituents and their biological importance. 9. Define proteoglycans and point out their functions. 10. Differentiate between glycoproteins and proteoglycans. CONTENTS: I. Chemical Nature of Carbohydrates II. Biomedical importance of Carbohydrates III. Monosaccharides - Classification - Forms of Isomerism of monosaccharides. - Importance of monosaccharides. - Monosaccharides derivatives. IV. Disaccharides - Reducing disaccharides. - Non- Reducing disaccharides V. Oligosaccarides. VI. Polysaccarides - Homopolysaccharides - Heteropolysaccharides - Carbohydrates of Biological Importance 10 CARBOHYDRATES OF BIOLOGICAL IMPORTANCE Chemical Nature of Carbohydrates Carbohydrates are polyhydroxyalcohols with an aldehyde or keto group. They are represented with general formulae Cn(H2O)n and hence called hydrates of carbons.
    [Show full text]
  • Structures and Characteristics of Carbohydrates in Diets Fed to Pigs: a Review Diego M
    Navarro et al. Journal of Animal Science and Biotechnology (2019) 10:39 https://doi.org/10.1186/s40104-019-0345-6 REVIEW Open Access Structures and characteristics of carbohydrates in diets fed to pigs: a review Diego M. D. L. Navarro1, Jerubella J. Abelilla1 and Hans H. Stein1,2* Abstract The current paper reviews the content and variation of fiber fractions in feed ingredients commonly used in swine diets. Carbohydrates serve as the main source of energy in diets fed to pigs. Carbohydrates may be classified according to their degree of polymerization: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Digestible carbohydrates include sugars, digestible starch, and glycogen that may be digested by enzymes secreted in the gastrointestinal tract of the pig. Non-digestible carbohydrates, also known as fiber, may be fermented by microbial populations along the gastrointestinal tract to synthesize short-chain fatty acids that may be absorbed and metabolized by the pig. These non-digestible carbohydrates include two disaccharides, oligosaccharides, resistant starch, and non-starch polysaccharides. The concentration and structure of non-digestible carbohydrates in diets fed to pigs depend on the type of feed ingredients that are included in the mixed diet. Cellulose, arabinoxylans, and mixed linked β-(1,3) (1,4)-D-glucans are the main cell wall polysaccharides in cereal grains, but vary in proportion and structure depending on the grain and tissue within the grain. Cell walls of oilseeds, oilseed meals, and pulse crops contain cellulose, pectic polysaccharides, lignin, and xyloglucans. Pulse crops and legumes also contain significant quantities of galacto-oligosaccharides including raffinose, stachyose, and verbascose.
    [Show full text]
  • Extending Enzyme Molecular Recognition with an Expanded Amino Acid Alphabet
    Extending enzyme molecular recognition with an expanded amino acid alphabet Claire L. Windlea,b, Katie J. Simmonsa,c, James R. Aulta,b, Chi H. Trinha,b, Adam Nelsona,c,1, Arwen R. Pearsona,2,3, and Alan Berrya,b,1 aAstbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom; bSchool of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom; and cSchool of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom Edited by Perry Allen Frey, University of Wisconsin–Madison, Madison, WI, and approved January 20, 2017 (received for review October 26, 2016) Natural enzymes are constructed from the 20 proteogenic amino for catalysis and arise through posttranslational modifications of acids, which may then require posttranslational modification or the the polypeptide chain (21, 22), allowing access to chemistries not recruitment of coenzymes or metal ions to achieve catalytic function. otherwise provided by the 20 proteogenic amino acids. Here, we demonstrate that expansion of the alphabet of amino acids Technologies for the protein engineer to incorporate Ncas into can also enable the properties of enzymes to be extended. A proteins at specifically chosen sites, either by genetic means (23–25) chemical mutagenesis strategy allowed a wide range of noncanon- or by chemical modification (26, 27), have recently been developed. ical amino acids to be systematically incorporated throughout an These approaches are powerful because, unlike traditional protein active site to alter enzymic substrate specificity. Specifically, 13 engineering with the 20 canonical amino acids, protein engineering different noncanonical side chains were incorporated at 12 different with Ncas has almost unlimited novel side-chain structures and positions within the active site of N-acetylneuraminic acid lyase chemistries from which to choose.
    [Show full text]
  • Reaction of Glucose Catalyzed by Framework and Extraframework Tin Sites in Zeolite Beta
    Reaction of Glucose Catalyzed by Framework and Extraframework Tin Sites in Zeolite Beta Thesis by Ricardo Bermejo-Deval In Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2014 (Defended 12 May 2014) ii 2014 Ricardo Bermejo-Deval All Rights Reserved iii ACKNOWLEDGEMENTS The past years at Caltech have been one of the most challenging periods of my life, learning to be a better person and being part of the world of science. I feel privileged to have interacted with such talented and inspiring colleagues and scientists, as well as those I have disagreed with. The variety of people I have encountered and the experiences I have gathered have helped me to gain scholarship, wisdom, confidence and critical thinking, as much as to become an open-minded person to any opinion or people. First and foremost, I am very grateful to my advisor and mentor, Professor Mark E. Davis, for his financial, scientific and personal support. I appreciate his patience, flexibility, advice and scientific discussions, helping me to grow and mature scientifically. I would like to thank the thesis committee Professors Richard Flagan, Jay Labinger and Theodor Agapie, for their discussions and kindness. I appreciate everyone in the Davis group for helping me in the lab throughout these years. Special thanks to Yasho for helping me get started in the lab, to Bingjun and Raj for scientific advice, and to Marat for helpful talks. I am also very thankful to Sonjong Hwang for SS NMR, David Vandervelde for NMR and Mona Shahgholi for mass spectrometry.
    [Show full text]
  • Conformational Study of the Open-Chain and Furanose Structures of D-Erythrose and D-Threose ⇑ Luis Miguel Azofra A, Ibon Alkorta A, , José Elguero A, Paul L
    Carbohydrate Research 358 (2012) 96–105 Contents lists available at SciVerse ScienceDirect Carbohydrate Research journal homepage: www.elsevier.com/locate/carres Conformational study of the open-chain and furanose structures of D-erythrose and D-threose ⇑ Luis Miguel Azofra a, Ibon Alkorta a, , José Elguero a, Paul L. A. Popelier b,c a Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain b Manchester Interdisciplinary Biocentre (MIB), 131 Princess Street, Manchester M1 7DN, United Kingdom c School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom article info abstract Article history: The potential energy surfaces for the different configurations of the D-erythrose and D-threose (open- Received 3 May 2012 chain, a- and b-furanoses) have been studied in order to find the most stable structures in the gas phase. Received in revised form 18 June 2012 For that purpose, a large number of initial structures were explored at B3LYP/6-31G(d) level. All the min- Accepted 19 June 2012 ima obtained at this level were compared and duplicates removed. A further reoptimization of the Available online 27 June 2012 remaining structures was carried out at B3LYP/6-311++G(d,p) level. We characterized 174 and 170 min- ima for the open-chain structures of D-erythrose and D-threose, respectively, with relative energies that Keywords: range over an interval of just over 50 kJ/mol. In the case of the furanose configurations, the number of D-Erythrose minima is smaller by approximately one to two dozen. G3B3 calculations on the most stable minima indi- D-Threose DFT cate that the a-furanose configuration is the most stable for both D-erythrose and D-threose.
    [Show full text]
  • Deoxyribose-5-Phosphate Aldolase As a Synthetic Catalyst'
    J. Am. Chem. SOC.1990, 112, 2013-2014 2013 chemical shift for the iminosilaacyl carbon at 6 299.07.3a3b Ad- Deoxyribose-5-phosphateAldolase as a Synthetic dition of 1 equiv of CN(XyI) to a benzene solution of 4, or reaction Catalyst' of 1 with 2 equiv of CN(Xyl), results in formation of a blue complex 5. The combustion analysis of isolated 5 is consistent Carlos F. Barbas, 111, Yi-Fong Wang, and Chi-Huey Wong* with a 1:2 adduct of 1 with isocyanide, Cp,Sc(CN(Xyl)),Si- (SiMe3)3. However, 'H NMR data for 5 indicate a complex Department of Chemistry structure and the presence of three inequivalent SiMe3 groups in The Research Institute of Scripps Clinic a 1 :1: 1 ratioss Formation of X-ray-quality, blue crystals from La Jolla, California 92037 diethvl ether allowed comdete characterization of this comwund. Received November 29, 1989 Tie crystal structure7'(Figure 1) shows that 5 is the pioduct of an isocyanide-coupling reaction that results in further rear- Enzyme-catalyzed stereocontrolled aldol condensations are rangements. The structure drawn in Scheme I reflects the ob- valuable in organic synthesis, particularly in the synthesis of served structural parameters. The chelate ring of 5 is derived from carbohydrates and related s~bstances?~~We report here an initial the two isoc anide groups and contains a Sc( 1)-N( 1) single bond study on the synthetic utility of a bacterial 2-deoxyribose-5- (2.133 (7) i),a longer (dative) Sc(l)-N(2) bond (2.324 (8) A), phosphate aldolase (DERA, EC 4.1.2.4) overexpressed in Es- and a C=C double bond (C(l)-C(2) = 1.375 (12) A).
    [Show full text]
  • Carbohydrate) (Lecture-Part 5)
    Course Code: CHEM3014 Course Name: Organic Chemistry V Unit: 4 (Carbohydrate) (Lecture-Part 5) For B.Sc. (Honours) Semester: VI By Dr. Abhijeet Kumar Department of Chemistry Mahatma Gandhi Central University Reactions of Monosaccharides Osazone Formation: The reaction between three moles of phenylhydrazine and one mole of aldose produces a crystalline product known as phenylosazone (Scheme 1). Phenylosazones crystallize readily (unlike sugars) and are useful derivatives for identifying sugars. Scheme 1: Phenyl osazone formation from aldose Osazone formation results in a loss of the chirality center at C2 but does not affect other chirality centers. Mechanism of Osazone Formation The reaction begins with the formation of phenyl hydrazone with one equivalent of phenylhydrazine . Upon treating the phenylhydrazones with two additional equivalents of phenylhydrazine, osazone formation occurs. one of the equivalents of phenylhydrazine is converted into aniline (PhNH2) and ammonia (NH3) (Scheme 2). Scheme 2: Proposed Mechanism for Phenyl osazone formation from aldose Although the mechanism of the phenylhydrazone formation in the first step is clear. But the next steps towards the formation of the osazone has been explained by various other mechanisms. Please refer to the study material provided below. BARRY, V., MITCHELL, P. Mechanism of Osazone Formation. Nature 175, 220 (1955). https://doi.org/10.1038/175220a0 Example of Osazone Formation Under mild conditions both D-glucose, D-mannose and D-Fructose form same osazone (Scheme 3). Scheme 3: Osazone formation from different aldoses Formation of identical osazone in case of both D-glucose and D-mannose indicates that both have the same configurations about C3, C4, and C5.
    [Show full text]
  • Appendix 1: Nonhazardous Chemicals
    Environmental Health & Safety Appendix 1: Nonhazardous Chemicals This list is not all-inclusive. Discharges with a pH between 5.5 and 9.5 Does not contain As, Ba, Cd, Cr, Pb, Hg, Se, Ag, Mn, Ni, Cu, or Zn A-B, C-F, G-L, M-P, R-X A-B Actin A-Adenosine, free base Adenosine 2' & 3'-monophosphate, disodium salt Adenosine 2' & 3'-monophosphate, free acid Adenosine 2',3'-cyclic monophosphate, sodium salt Adenosine 3',5'-cyclic monophosphate, sodium salt Adenosine 3'-monophosphate, sodium salt Adenosine 5'-diphosphate, sodium salt Adenosine 5'-monophosphate Adenosine 5'-monophosphate, disodium salt Adenosine 5'-monophosphate, sodium salt Adonitol; Ribitol Agar; Bacto agar Agarose Alginic acid, sodium salt; Sodium alginate ß-Alanine DL-Alanine L-Alanine Albumin, bovine Albumin, bovine, methylated Albumin, human Alcohol dehydrogenase Aldolase, type X DL-Aminobutyric acid; GABA 4-Amino-2-methyl-1-naphthol; Vitamin K5 Amylase alpha-Amylase, type II-A alpha-Amylase, type VI-B ß-Amylase, sweet potato Amyloglucosidase Amylose Apyrase, grade VI D-Arabinose L(+) Arabinose D-Arabitol Arginase Arginine L-(+)-Arginine D-Asparagine, monohydrate DL-Asparagine L-Asparagine Aspartamene; Asp-phe methyl ester; L-Aspartyl-L-phenylalanine methyl ester D-Aspartic acid DL-Aspartic acid L-Aspartic acid L-Aspartic acid, monosodium salt Autex developer and replenisher Baclofen Bacto peptone; Peptone Base waste (aqueous), neutralized to a pH between 5 and 11.5 (does not contain As, Ba, Cd, Cr, Pb, Hg, Se, Ag, Mn, Ni, Cu, or Zn) Bayberry wax Bentonite ß-Glucuronidase,
    [Show full text]
  • Carbohydrates Hydrates of Carbon: General Formula Cn(H2O)N Plants
    Chapter 25: Carbohydrates hydrates of carbon: general formula Cn(H2O)n Plants: photosynthesis hν 6 CO2 + H2O C6H12O6 + 6 O2 Polymers: large molecules made up of repeating smaller units (monomer) Biopolymers: Monomer units: carbohydrates (chapter 25) monosaccharides peptides and proteins (chapter 26) amino acids nucleic acids (chapter 28) nucleotides 315 25.1 Classification of Carbohydrates: I. Number of carbohydrate units monosaccharides: one carbohydrate unit (simple carbohydrates) disaccharides: two carbohydrate units (complex carbohydrates) trisaccharides: three carbohydrate units polysaccharides: many carbohydrate units CHO H OH HO HO HO H HO HO O HO O glucose H OH HO HO OH HO H OH OH CH2OH HO HO HO O HO O HO HO O HO HO O HO HO HO O O O O O HO HO O HO HO HO O O HO HO HO galactose OH + glucose O glucose = lactose polymer = amylose or cellulose 316 160 II. Position of carbonyl group at C1, carbonyl is an aldehyde: aldose at any other carbon, carbonyl is a ketone: ketose III. Number of carbons three carbons: triose six carbons: hexose four carbons: tetrose seven carbons: heptose five carbons: pentose etc. IV. Cyclic form (chapter 25.5) CHO CHO CHO CHO CH2OH H OH HO H H OH H OH O CH2OH H OH H OH HO H HO H CH2OH H OH H OH H OH CH2OH H OH H OH CH OH 2 CH2OH glyceraldehyde threose ribose glucose fructose (triose) (tetrose) (pentose) (hexose) (hexose) 317 (aldohexose) (ketohexose) 25.2: Depicting carbohydrates stereochemistry: Fischer Projections: representation of a three-dimensional molecule as a flat structure.
    [Show full text]
  • Preparation of D-Arabinose-1-C^14 and D-Ribose-1-C^14
    Journal of Research of the National Bureau of Standards Vol. 51, No.6, December 1953 Research Paper 2458 14 Preparation of D-Arabinose-I-C'4and D-Ribose-l-C I Harriet L. Frush and Horace S. Isbell 1 By application of t he cyanohydrin synthesis to D-erythroso, D-arabinose-I-C14 a nd D­ t ribose-I-C" have been prepared in overall radiochemical yields of 30 and 8.5 percent, respectively. General acid catalysts in t he cyanohydrin reaction appear to favor format ion of t he ambonic epimer. The epimeri c acids res ul ting from the reaction of labeled cyanide and D-erythroso, and subsequent hydrolysis, were separated as crystalline potassium D­ arabonate-l-C14 and cadmium D-ribonate-l-C'4, respectively. The salts we re conver ted to the corresponding lactones, and t hese were red uced to t he sugars by usc of sodium amalgam in t he prese nce of sodi um a cid oxalate. 1. Introduction D-arabonate-l-C'4 was converted to D-arabono--y­ (" lactone-l-CI4, and this was reduced with sodium As part of it program to make position-labeled amalgam in the presence of sodium acid oxala te. 3 sugars available for research w'orkers in other labora­ A 56-percent yield of the crystalline D-arabinose-l-CI4 tories, methods have been developed at the National was separated without carrier ; by use of carrier, the Bureau of Standards for the preparation of D-glucose- radioch emical yield was increased to 60 percent. 1-CI4, D-mannose-1-CI", D-mannitol-l-C'4, n-fruc­ As potassium D-arabonate-l-CI4 was produced in 50- tose-l,6-C'\ lactose-l-C''', and D-arabinose-5-CI4 [1, percent yield, the over-all radiochemical yield of ~I 2, 3, 4, 5, 6).2 The present report gives methods D-arabinose-l-CI4 was 30 percent, based on Lhe for the preparation of D-arabinose-l-CI4 and n-ribose­ cyanide originally used.
    [Show full text]
  • Principles of Chemical Nomenclature a GUIDE to IUPAC RECOMMENDATIONS Principles of Chemical Nomenclature a GUIDE to IUPAC RECOMMENDATIONS
    Principles of Chemical Nomenclature A GUIDE TO IUPAC RECOMMENDATIONS Principles of Chemical Nomenclature A GUIDE TO IUPAC RECOMMENDATIONS G.J. LEIGH OBE TheSchool of Chemistry, Physics and Environmental Science, University of Sussex, Brighton, UK H.A. FAVRE Université de Montréal Montréal, Canada W.V. METANOMSKI Chemical Abstracts Service Columbus, Ohio, USA Edited by G.J. Leigh b Blackwell Science © 1998 by DISTRIBUTORS BlackweilScience Ltd Marston Book Services Ltd Editorial Offices: P0 Box 269 Osney Mead, Oxford 0X2 0EL Abingdon 25 John Street, London WC1N 2BL Oxon 0X14 4YN 23 Ainslie Place, Edinburgh EH3 6AJ (Orders:Tel:01235 465500 350 Main Street, Maiden Fax: MA 02 148-5018, USA 01235 465555) 54 University Street, Carlton USA Victoria 3053, Australia BlackwellScience, Inc. 10, Rue Casmir Delavigne Commerce Place 75006 Paris, France 350 Main Street Malden, MA 02 148-5018 Other Editorial Offices: (Orders:Tel:800 759 6102 Blackwell Wissenschafts-Verlag GmbH 781 388 8250 KurfUrstendamm 57 Fax:781 388 8255) 10707 Berlin, Germany Canada Blackwell Science KK Copp Clark Professional MG Kodenmacho Building 200Adelaide St West, 3rd Floor 7—10 Kodenmacho Nihombashi Toronto, Ontario M5H 1W7 Chuo-ku, Tokyo 104, Japan (Orders:Tel:416 597-1616 800 815-9417 All rights reserved. No part of Fax:416 597-1617) this publication may be reproduced, stored in a retrieval system, or Australia BlackwellScience Pty Ltd transmitted, in any form or by any 54 University Street means, electronic, mechanical, Carlton, Victoria 3053 photocopying, recording or otherwise, (Orders:Tel:39347 0300 except as permitted by the UK Fax:3 9347 5001) Copyright, Designs and Patents Act 1988, without the prior permission of the copyright owner.
    [Show full text]
  • Theoretical Study of the Mutarotation of Erythrose and Threose: Acid Catalysis ⇑ Luis Miguel Azofra , , Ibon Alkorta , José Elguero
    Carbohydrate Research 372 (2013) 1–8 Contents lists available at SciVerse ScienceDirect Carbohydrate Research journal homepage: www.elsevier.com/locate/carres Theoretical study of the mutarotation of erythrose and threose: acid catalysis ⇑ Luis Miguel Azofra , , Ibon Alkorta , José Elguero Instituto de Química Médica (I.Q.M.-C.S.I.C.), Juan de la Cierva, 3, E-28006 Madrid, Spain article info abstract Article history: The acid catalysis of the mutarotation mechanism in the two aldotetroses, D-erythrose and D-threose, has Received 22 November 2012 been studied at B3LYP/6-311++G(d,p) computational level in gas phase and in solution employing the Received in revised form 18 January 2013 PCM–water model. The open-chain, the furanose and the connecting TS structures have been character- Accepted 21 January 2013 ized. To study the enhancing effect of acid groups on the electrophilicity of the carbonyl carbon atom, four Available online 29 January 2013 + situations have been considered: (i) a classical Lewis acid as BH3; (ii) a classical hard-Pearson acid as Na ; + + + (iii) classical Brønsted acids as H and H3O ; and (iv) a combined strategy using H3O and one bridge-H2O Keywords: molecule as assistant in the proton transfer process. All the acidic groups reduce the activation energy Hemiacetal reaction with exception of the Na+, which can act, in some cases, as inhibitor. It is greatly reduced by the presence DFT-calculations Lewis acid of Brønsted acids (iii) and through the combined strategy (iv). For this last mechanism, the electronic acti- À1 À1 Hard-Pearson acid vation energies are between 12 and 43 kJ mol in vacuum and between 13 and 25 kJ mol in water Brønsted acid solution, through the use of the PCM model.
    [Show full text]