DOCSLIB.ORG

Carbohydrates

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Carbohydrates Carbohydrates Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 1 Carbohydrates Carbohydrates are ▪ A major source of energy from our diet. ▪ Composed of the elements C, H, and O. ▪ Also called saccharides, which means “sugars.” Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 2 Carbohydrates Carbohydrates ▪ Are produced by photosynthesis in plants. ▪ Such as glucose are synthesized in plants from CO2, H2O, and energy from the sun. ▪ Are oxidized in living cells (respiration) to produce CO2, H2O, and energy. Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 3 ▪ Carbohydrates – polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n, or compounds that can be hydrolyzed to them. (sugars or saccharides) ▪ Monosaccharides – carbohydrates that cannot be hydrolyzed to simpler carbohydrates; eg. Glucose or fructose. ▪ Disaccharides – carbohydrates that can be hydrolyzed into two monosaccharide units; eg. Sucrose, which is hydrolyzed into glucose and fructose. ▪ Oligosaccharides – carbohydrates that can be hydrolyzed into a few monosaccharide units. ▪ Polysaccharides – carbohydrates that are are polymeric sugars; eg Starch or cellulose. 4 ▪ Aldose – polyhydroxyaldehyde, eg glucose ▪ Ketose – polyhydroxyketone, eg fructose ▪ Triose, tetrose, pentose, hexose, etc. – carbohydrates that contain three, four, five, six, etc. carbons per molecule (usually five or six); eg. Aldohexose, ketopentose, etc. ▪ Reducing sugar – a carbohydrate that is oxidized by Tollen’s, Fehling’s or Benedict’s solution. ▪ Tollen’s: Ag+ → Ag (silver mirror) ▪ Fehling’s or Benedict’s: Cu2+ (blue) → Cu1+ (red ppt) ▪ These are reactions of aldehydes and alpha-hydroxyketones. ▪ All monosaccharides (both aldoses and ketoses) and most* disaccharides are reducing sugars. ▪ *Sucrose (table sugar), a disaccharide, is not a reducing sugar. 5 Classification ◼ Monosaccharides (monoses or glycoses) ◼ Trioses, tetroses, pentoses, hexoses ◼ Oligosaccharides ◼ Di, tri, tetra, penta, up to 9 or 10 ◼ Most important are the disaccharides ◼ Polysaccharides or glycans ◼ Homo and Heteropolysaccharides ◼ Complex carbohydrates 6 Types of Carbohydrates 7 Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings Monosaccharides Monosaccharides consist of ▪ 3 to 6 carbon atoms, typically. ▪ A carbonyl group (aldehyde or ketone). ▪ Several hydroxyl groups. ▪ also known as simple sugars ▪ classified by 1. the number of carbons and 2. whether aldoses or ketoses ▪ most (99%) are straight chain compounds ▪ D-glyceraldehyde is the simplest of the aldoses (aldotriose) ▪ all other sugars have the ending ose (glucose, galactose, ribose, lactose, etc…) 8 Properties ▪ Differences in structures of sugars are responsible for variations in properties ▪ Physical Crystalline form; ▪ solubility; rotatory power ▪ Chemical Reactions ▪ oxidations, reductions, condensations ▪ Physiological Nutritive value ▪ (human, bacterial); sweetness; absorption 9 Aldoses Aldoses are monosaccharides O ▪ With an aldehyde group. ║ ▪ With many hydroxyl (─OH) C─H aldose groups. │ triose (3 C atoms) H─ C─OH tetrose (4 C atoms) │ pentose (5 C atoms) H─ C─OH hexose (6 C atoms) │ CH2OH Erythose, an aldotetrose 10 Aldose sugars H H H H H C O C O C O C O C O (H C OH)n H C OH H C OH H C OH H C OH CH OH H C OH H C OH H C OH 2 CH2OH Aldose Aldotriose CH2OH H C OH H C OH n = 1 Aldotetrose CH2OH n = 2 H C OH Aldopentose CH OH n = 3 2 Aldohexose n = 4 11 Ketoses Ketoses are monosaccharides CH2OH ▪ With a ketone group. │ ▪ With many hydroxyl (─OH) C=O ketose groups. │ OH ─ C─ H triose (3 C atoms) │ tetrose (4 C atoms) H─ C─OH pentose (5 C atoms) │ hexose (6 C atoms) H─C─OH │ CH2OH Fructose, a ketohexose 12 Ketose sugars CH2OH CH2OH CH2OH CH2OH C O CH2OH C O C O C O H C OH C O (H C OH)n H C OH CH2OH H C OH H C OH CH2OH CH2OH CH2OH H OH Ketose Ketotriose Ketotetrose Ketopentose n = 0 n = 1 H C OH n = 2 CH2OH Ketohexose n = 3 13 Enantiomers and epimers H H H H C O C O C O C O HO C H HO C H H C OH OH C H HO C H HO C H H C OH OH C H H C OH HO C H CH2OH CH2OH H C OH H C OH these two aldotetroses are enantiomers. They are stereoisomers that are mirror CH2OH CH2OH images of each other these two aldohexoses are C-4 epimers. they differ only in the position of the hydroxyl group on one asymmetric carbon (carbon 4) 14 Enantiomers ▪ Pairs of stereoisomers ▪ Designated by D- or L- at the start of the name. ▪ They are mirror images ▪ that can’t be overlapped. 15 Enantiomers 16 17 Aldotetrose 18 Aldopentoses: C5, three chiral carbons, eight stereoisomers 19 Learning Check Identify each as aldo- or keto- and as tetrose, pentose, or hexose: O CH2OH C H C O H C OH HO C H H C OH H C OH H C OH H C OH CH2OH CH2OH A B 20 Solution A. aldohexose B. ketopentose 21 Carbohydrates Structures of Monosaccharides Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings 22 Structural representation of sugars ▪ Fisher projection: straight chain representation ▪ Haworth projection: simple ring in perspective ▪ Conformational representation: chair and boat configurations 23 Fischer Projections A Fischer projection ▪ Is used to represent carbohydrates. ▪ Places the most oxidized group at the top. ▪ Shows chiral carbons as the intersection of vertical and horizontal lines. Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 24 D and L Rotations In a Fischer projection, the −OH group on the ▪ Chiral carbon farthest from the carbonyl group determines an L or D isomer. ▪ Left is assigned the letter L for the L-isomer. ▪ Right is assigned the letter D for the D-isomer. Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 25 ▪ (+)-glucose? An aldohexose Emil Fischer (1902) Four chiral centers, 2n=24= 16 stereoisomers 26 aldohexoses CHO CHO CHO CHO CHO CHO H OH HO H HO H H OH H OH HO H H OH HO H H OH HO H HO H H OH H OH HO H H OH HO H H OH HO H H OH HO H H OH HO H H OH HO H CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CHO CHO CHO CHO CHO CHO HO H H OH H OH HO H HO H H OH HO H H OH H OH HO H H OH HO H H OH HO H HO H H OH HO H H OH H OH HO H H OH HO H H OH HO H CH2OH CH2OH CH2OH CH2OH CH2OH CH2OH CHO CHO CHO CHO H OH HO H HO H H OH HO H H OH HO H H OH HO H H OH HO H H OH H OH HO H H OH HO H CH2OH CH2OH CH2OH CH2OH 27 Optical isomerism ▪ A property exhibited by any compound whose mirror images are non-superimposable ▪ Asymmetric compounds rotate plane polarized light POLARIMETRY Measurement of optical activity in chiral or asymmetric molecules using plane polarized light Molecules may be chiral because of certain atoms or because of chiral axes or chiral planes Measurement uses an instrument called a polarimeter Rotation is either (+) dextrorotatory or (-) levorotatory 28 POLARIMETER 29 Examples of D and L Isomers of Monosaccharides O O C H C H O HO H H OH C H H OH HO H H OH H OH H OH H OH HO H H OH H OH CH OH CH2OH CH2OH 2 D-glucose D-ribose L-galactose 30 Learning Check Identify each as the D or L isomer. A. B. C. O CH2OH C H O O HO H C H HO H HO H H OH H OH HO H HO H H OH CH OH CH2OH CH2OH 2 __-ribose __- threose __- fructose 31 Solution Identify each as the D or L isomer. A. B. C. O CH2OH C H O O HO H C H HO H HO H H OH H OH HO H HO H H OH CH OH CH2OH CH2OH 2 L-ribose L-threose D-fructose 32 Epimers – stereoisomers that differ only in configuration about one chiral center. CHO CHO H OH HO H HO H HO H H OH H OH H OH H OH CH2OH CH2OH D-glucose D-mannose epimers 33 D-Glucose D-glucose is ▪ Found in fruits, corn syrup, and honey. ▪ An aldohexose with the formula C6H12O6. ▪ Known as blood sugar in the body. ▪ The monosaccharide in polymers of starch, cellulose, and Copyright © 2007 by Pearson Education, Inc glycogen. Publishing as Benjamin Cummings 34 Blood Glucose Level In the body, ▪ Glucose has a normal blood level of 70-90 mg/dL. ▪ A glucose tolerance test measures blood glucose for Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin several hours Cummings after ingesting glucose. 35 D-Fructose D-fructose ▪ Is a ketohexose CH2OH C6H12O6. C O ▪ Is the sweetest HO C H carbohydrate. H C OH ▪ Is found in fruit juices and honey. H C OH ▪ Converts to CH2OH glucose in the body. Copyright © 2007 by Pearson Education, Inc D-Fructose Publishing as Benjamin Cummings 36 D-Galactose D-galactose is O ▪ An aldohexose C6H12O6. C H ▪ Not found free in nature. H C OH ▪ Obtained from lactose, a HO C H disaccharide. HO C H ▪ A similar structure to glucose except for the H C OH –OH on C4. CH2OH D-Galactose 37 Learning Check Draw the structure and Fischer projection of D-fructose. 38 Solution CH OH CH2OH 2 │ C O C=O HO C H HO H H C OH H OH H C OH H OH CH2OH CH2OH D-Fructose Fischer projection 39 Carbohydrates Cyclic Structures of Monosaccharides CH2OH O OH OH OH OH Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings 40 Cyclic Structures Cyclic structures ▪ Are the prevalent form of monosaccharides with 5 or 6 carbon atoms.
Recommended publications
  • Carbohydrates: Structure and Function

    Carbohydrates: Structure and Function

    CARBOHYDRATES: STRUCTURE AND FUNCTION Color index: . Very important . Extra Information. “ STOP SAYING I WISH, START SAYING I WILL” 435 Biochemistry Team *هذا العمل ﻻ يغني عن المصدر المذاكرة الرئيسي • The structure of carbohydrates of physiological significance. • The main role of carbohydrates in providing and storing of energy. • The structure and function of glycosaminoglycans. OBJECTIVES: 435 Biochemistry Team extra information that might help you 1-synovial fluid: - It is a viscous, non-Newtonian fluid found in the cavities of synovial joints. - the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement O 2- aldehyde = terminal carbonyl group (RCHO) R H 3- ketone = carbonyl group within (inside) the compound (RCOR’) 435 Biochemistry Team the most abundant organic molecules in nature (CH2O)n Carbohydrates Formula *hydrate of carbon* Function 1-provides important part of energy Diseases caused by disorders of in diet . 2-Acts as the storage form of energy carbohydrate metabolism in the body 3-structural component of cell membrane. 1-Diabetesmellitus. 2-Galactosemia. 3-Glycogen storage disease. 4-Lactoseintolerance. 435 Biochemistry Team Classification of carbohydrates monosaccharides disaccharides oligosaccharides polysaccharides simple sugar Two monosaccharides 3-10 sugar units units more than 10 sugar units Joining of 2 monosaccharides No. of carbon atoms Type of carbonyl by O-glycosidic bond: they contain group they contain - Maltose (α-1, 4)= glucose + glucose -Sucrose (α-1,2)= glucose + fructose - Lactose (β-1,4)= glucose+ galactose Homopolysaccharides Heteropolysaccharides Ketone or aldehyde Homo= same type of sugars Hetero= different types Ketose aldose of sugars branched unBranched -Example: - Contains: - Contains: Examples: aldehyde group glycosaminoglycans ketone group.
  • United States Patent Office

    United States Patent Office

    - 2,926,180 United States Patent Office Patented Feb. 23, 1960 2 cycloalkyl, etc. These substituents R and R' may also be substituted with various groupings such as carboxyl 2,926,180 groups, sulfo groups, halogen atoms, etc. Examples of CONDENSATION OF AROMATIC KETONES WITH compounds which are included within the scope of this CARBOHYDRATES AND RELATED MATER ALS 5 general formula are acetophenone, propiophenone, benzo Carl B. Linn, Riverside, Ill., assignor, by mesne assign phenone, acetomesitylene, phenylglyoxal, benzylaceto ments, to Universal Oil Products Company, Des phenone, dypnone, dibenzoylmethane, benzopinacolone, Plaines, Ill., a corporation of Delaware dimethylaminobenzophenone, acetonaphthalene, benzoyl No Drawing. Application June 18, 1957 naphthalene, acetonaphthacene, benzoylnaphthacene, ben 10 zil, benzilacetophenone, ortho-hydroxyacetophenone, para Serial No. 666,489 hydroxyacetophenone, ortho - hydroxy-para - methoxy 5 Claims. (C. 260-345.9) acetophenone, para-hydroxy-meta-methoxyacetophenone, zingerone, etc. This application is a continuation-in-part of my co Carbohydrates which are condensed with aromatic pending application Serial No. 401,068, filed December 5 ketones to form a compound selected from the group 29, 1953, now Patent No. 2,798,079. consisting of an acylaryl-desoxy-alditol and an acylaryl This invention relates to a process for interacting aro desoxy-ketitol include simple sugars, their desoxy- and matic ketones with carbohydrates and materials closely omega-carboxy derivatives, compound sugars or oligo related to carbohydrates. The process relates more par saccharides, and polysaccharides. ticularly to the condensation of simple sugars, their 20 Simple sugars include dioses, trioses, tetroses, pentoses, desoxy- and their omega-carboxy derivatives, compound hexoses, heptoses, octoses, nonoses, and decoses. Com sugars or oligosaccharides, and polysaccharides with aro pound sugars include disaccharides, trisaccharides, and matic ketones in the presence of a hydrogen fluoride tetrasaccharides.
  • Structural Features

    Structural Features

    1 Structural features As defined by the International Union of Pure and Applied Chemistry gly- cans are structures of multiple monosaccharides linked through glycosidic bonds. The terms sugar and saccharide are synonyms, depending on your preference for Arabic (“sukkar”) or Greek (“sakkēaron”). Saccharide is the root for monosaccha- rides (a single carbohydrate unit), oligosaccharides (3 to 20 units) and polysac- charides (large polymers of more than 20 units). Carbohydrates follow the basic formula (CH2O)N>2. Glycolaldehyde (CH2O)2 would be the simplest member of the family if molecules of two C-atoms were not excluded from the biochemical repertoire. Glycolaldehyde has been found in space in cosmic dust surrounding star-forming regions of the Milky Way galaxy. Glycolaldehyde is a precursor of several organic molecules. For example, reaction of glycolaldehyde with propenal, another interstellar molecule, yields ribose, a carbohydrate that is also the backbone of nucleic acids. Figure 1 – The Rho Ophiuchi star-forming region is shown in infrared light as captured by NASA’s Wide-field Infrared Explorer. Glycolaldehyde was identified in the gas surrounding the star-forming region IRAS 16293-2422, which is is the red object in the centre of the marked square. This star-forming region is 26’000 light-years away from Earth. Glycolaldehyde can react with propenal to form ribose. Image source: www.eso.org/public/images/eso1234a/ Beginning the count at three carbon atoms, glyceraldehyde and dihydroxy- acetone share the common chemical formula (CH2O)3 and represent the smallest carbohydrates. As their names imply, glyceraldehyde has an aldehyde group (at C1) and dihydoxyacetone a carbonyl group (at C2).
  • Monosaccharide Disaccharide Oligosaccharide Polysaccharide Monosaccharide

    Monosaccharide Disaccharide Oligosaccharide Polysaccharide Monosaccharide

    Carbohydrates Classification of Carbohydrates monosaccharide disaccharide oligosaccharide polysaccharide Monosaccharide is not cleaved to a simpler carbohydrate on hydrolysis glucose, for example, is a monosaccharide Disaccharide is cleaved to two monosaccharides on hydrolysis these two monosaccharides may be the same or different C12H22O11 + H2O C6H12O6 + C6H12O6 glucose sucrose (a monosaccharide) fructose (a disaccharide) (a monosaccharide) Higher Saccharides oligosaccharide: gives two or more monosaccharide units on hydrolysis is homogeneous—all molecules of a particular oligosaccharide are the same, including chain length polysaccharide: yields "many" monosaccharide units on hydrolysis mixtures of the same polysaccharide differing only in chain length Some Classes of Carbohydrates No. of carbons Aldose Ketose 4 Aldotetrose Ketotetrose 5 Aldopentose Ketopentose 6 Aldohexose Ketopentose 7 Aldoheptose Ketoheptose 8 Aldooctose Ketooctose Fischer Projections and D-L Notation Fischer Projections Fischer Projections Fischer Projections of Enantiomers Enantiomers of Glyceraldehyde CH O CH O H OH HO H D L CH2OH CH2OH (+)-Glyceraldehyde (–)-Glyceraldehyde The Aldotetroses An Aldotetrose 1 CH O 2 H OH 3 H OH D 4 CH2OH stereochemistry assigned on basis of whether configuration of highest-numbered stereogenic center is analogous to D or L-glyceraldehyde An Aldotetrose 1 CH O 2 H OH 3 H OH 4 CH2OH D-Erythrose The Four Aldotetroses CH O CH O H OH HO H D-Erythrose and L-erythrose are H OH HO H enantiomers CH2OH CH2OH D-Erythrose L-Erythrose The Four
  • Download Product Insert (PDF)

    Download Product Insert (PDF)

    PRODUCT INFORMATION D-(+)-Glyceraldehyde Item No. 16493 CAS Registry No.: 453-17-8 Formal Name: (2R)-2,3-dihydroxy-propanal Synonyms: D-Glyceraldehyde, D-Glycerose, NSC 91534 MF: C H O CHO 3 6 3 HO FW: 90.1 Purity: ≥85% OH Supplied as: A neat oil Storage: -20°C Stability: ≥2 years Information represents the product specifications. Batch specific analytical results are provided on each certificate of analysis. Laboratory Procedures D-(+)-Glyceraldehyde is supplied as a neat oil. A stock solution may be made by dissolving the D-(+)-glyceraldehyde in the solvent of choice. D-(+)-Glyceraldehyde is soluble in organic solvents such as ethanol, DMSO, and dimethyl formamide, which should be purged with an inert gas. The solubility of D-(+)-glyceraldehyde in these solvents is approximately 30 mg/ml. Further dilutions of the stock solution into aqueous buffers or isotonic saline should be made prior to performing biological experiments. Ensure that the residual amount of organic solvent is insignificant, since organic solvents may have physiological effects at low concentrations. Organic solvent-free aqueous solutions of D-(+)-glyceraldehyde can be prepared by directly dissolving the neat oil in aqueous buffers. The solubility of D-(+)-glyceraldehyde in PBS, pH 7.2, is approximately 10 mg/ml. We do not recommend storing the aqueous solution for more than one day. Description D-(+)-Glyceraldehyde is an intermediate in carbohydrate metabolism. It is phosphorylated by triose kinase to produce D-glyceraldehyde 3-phosphate, an intermediate in glycolysis, gluconeogenesis, photosynthesis, and other metabolic pathways.1-3 References 1. Ronimus, R.S. and Morgan, H.W.
  • Patent No .: US 10703789 B2

    Patent No .: US 10703789 B2

    US010703789B2 ( 12 ) United States Patent ( 10 ) Patent No.: US 10,703,789 B2 De Fougerolles et al. (45 ) Date of Patent: * Jul. 7 , 2020 (54 ) MODIFIED POLYNUCLEOTIDES FOR THE (2013.01 ) ; A61K 38/36 ( 2013.01 ) ; A61K PRODUCTION OF SECRETED PROTEINS 38/363 ( 2013.01 ) ; A61K 38/44 ( 2013.01) ; A61K 38/4833 (2013.01 ) ; A61K 38/4846 ( 71 ) Applicant : Moderna TX , Inc., Cambridge, MA (2013.01 ) ; A61K 39/3955 ( 2013.01) ; A61K (US ) 47/10 (2013.01 ) ; A61K 47/54 (2017.08 ) ; A61K 47/542 (2017.08 ) ; A61K 48/0033 ( 2013.01 ) ; ( 72 ) Inventors: Antonin De Fougerolles, Waterloo A61K 48/0066 (2013.01 ) ; A61K 48/0075 ( BE ) ; Justin Guild , Framingham , MA (2013.01 ) ; CO7K 14/47 ( 2013.01 ) ; CO7K (US ) 14/475 ( 2013.01) ; CO7K 14/505 (2013.01 ) ; ( 73 ) Assignee : Moderna TX , Inc., Cambridge , MA CO7K 14/525 (2013.01 ) ; C07K 14/56 (US ) (2013.01 ) ; CO7K 14/565 ( 2013.01 ) ; CO7K 14/745 (2013.01 ) ; C07K 14/75 ( 2013.01) ; ( * ) Notice: Subject to any disclaimer , the term of this CO7K 16/2887 ( 2013.01 ) ; CO7K 16/32 patent is extended or adjusted under 35 ( 2013.01) ; CO7K 19/00 ( 2013.01) ; C12N U.S.C. 154 (b ) by 0 days . 9/0069 ( 2013.01) ; C12N 9/644 ( 2013.01 ) ; C12N 15/85 (2013.01 ) ; C12N 15/88 This patent is subject to a terminal dis ( 2013.01 ) ; C12Y 113/12007 (2013.01 ) ; C12Y claimer . 304/21005 (2013.01 ) ; C12Y 304/21022 (2013.01 ) ; A61K 9/0019 (2013.01 ) ; A61K (21 ) Appl. No.: 16 /438,978 48/00 (2013.01 ) ; C12N 2840/00 (2013.01 ) ( 22 ) Filed : Jun .
  • Structures and Characteristics of Carbohydrates in Diets Fed to Pigs: a Review Diego M

    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.
  • Did an Earlier Genetic Molecule Predate DNA and RNA? 9 January 2012, by Richard Harth

    Did an Earlier Genetic Molecule Predate DNA and RNA? 9 January 2012, by Richard Harth

    Simpler times: Did an earlier genetic molecule predate DNA and RNA? 9 January 2012, by Richard Harth have acted as genetic precursors to RNA and DNA is to examine other nucleic acids that differ slightly in their chemical composition, yet still possess critical properties of self-assembly and replication as well as the ability to fold into shapes useful for biological function. According to Chaput, one interesting contender for the role of early genetic carrier is a molecule known as TNA, whose arrival on the primordial scene may have predated its more familiar kin. A nucleic acid similar in form to both DNA and RNA, TNA differs in the sugar component of its structure, using threose rather than deoxyribose (as in DNA) or ribose (as in The nucleic acid TNA may have acted as a precursor RNA) to compose its backbone. molecule to DNA and RNA, bearing genetic information and performing important biological functions. Photo: Public domain In an article released online today in the journal Nature Chemistry, Chaput and his group describe the Darwinian evolution of functional TNA molecules from a large pool of random sequences. (PhysOrg.com) -- In the chemistry of the living This is the first case where such methods have world, a pair of nucleic acids-DNA and RNA-reign been applied to molecules other than DNA and supreme. As carrier molecules of the genetic code, RNA, or very close structural analogues thereof. they provide all organisms with a mechanism for Chaput says "the most important finding to come faithfully reproducing themselves as well as from this work is that TNA can fold into complex generating the myriad proteins vital to living shapes that can bind to a desired target with high systems.
  • T. TRIOSE PHOSPHATE ISOMERASE Background

    T. TRIOSE PHOSPHATE ISOMERASE Background

    T. TRIOSE PHOSPHATE ISOMERASE Background O H OH 2- 2- O3PO OH O3PO O Dihydroxyacetone phosphate D-Glyceraldehyde-3-phosphate (DHAP) (GAP) Figure T.1. The reaction catalyzed by triose phosphate isomerase. Note that the reaction can proceed in either direction. Triose phosphate isomerase (TIM) is one of the best studied enzymes out there. A glycolytic enzyme, TIM is present in virtually all organisms. It catalyzes the interconversion of dihydroxyacetone phosphate (DHAP) with D-glyceraldehyde-3-phosphate (GAP; Figure T.1). The individual principally associated with TIM is Jeremy Knowles, who has written two excellent reviews that cover most of the material in these notes.1 The structure of TIM was solved by Greg Petsko in the mid-1970’s, at a time when relatively few enzyme structures were known. From my perspective, the value of TIM as a point of discussion lies in the following topics: • General acid/base catalysis • Moderation of pKa’s in the enzyme active site • Sequestration of reactive intermediates • Optimization of catalytic efficiency • Cryptic stereochemistry Each topic will be covered below. Glycolysis Glucose is metabolized anaerobically through the glycolytic pathway which uses 11 enzymes to convert glucose to two molecules of lactic acid along with the production of two molecules of ATP from ADP and inorganic phosphate (Eq. T.1) C6H12O6 + 2 ADP + 2 Pi → 2 C3H6O3 + 2 ATP (Eq. T.1) To obtain a better understanding of glycolysis, any textbook or Wikipedia entry will do. However, to place TIM’s role in context, it appears at an important juncture in glycolysis, where the last hexose in the cycle, fructose-1,6-bisphosphate, is degraded to glyceraldehyde-3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP; Figure T.2).
  • Chapter 6 Carbohydrates Outline 6.1 Classes of Carbohydrates 6.1

    Chapter 6 Carbohydrates Outline 6.1 Classes of Carbohydrates 6.1

    2/25/2015 Outline Lecture Presentation • 6.1 Classes of Carbohydrates • 6.2 Functional Groups in Monosaccharides Chapter 6 • 6.3 Stereochemistry in Monosaccharides Carbohydrates • 6.4 Reactions of Monosaccharides • 6.5 Disaccharides • 6.6 Polysaccharides Julie Klare • 6.7 Carbohydrates and Blood Fortis College Smyrna, GA © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. 6.1 Classes of Carbohydrates 6.1 Classes of Carbohydrates • The simplest carbohydrates are • Disaccharides consist of two monosaccharide monosaccharides (mono is Greek for “one,” units joined together. sakkhari is Greek for “sugar”). • A disaccharide can be split into two • These often sweet-tasting sugars cannot be monosaccharide units. Ordinary table sugar, broken down into smaller carbohydrates. sucrose, C12H22O11, is a disaccharide that can be broken up, through hydrolysis, into the • The common carbohydrate glucose, C6H12O6, is a monosaccharide. monosaccharides glucose and fructose. • Monosaccharides contain carbon, hydrogen, • Oligosaccharidesare carbohydrates and oxygen and have the general formula containing three to nine monosaccharide units. The blood-typing groups known as ABO are Cn(H2O)n, where n is a whole number 3 or higher. oligosaccharides. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. 6.1 Classes of Carbohydrates 6.1 Classes of Carbohydrates • When 10 or more monosaccharide units are joined together, the large molecules that result are polysaccharides (poly is Greek for “many”). • The sugar units can be connected in one continuous chain or the chain can be branched. • Starch, a polysaccharide in plants, contains branched chains of glucose that can be broken down to produce energy. © 2014 Pearson Education, Inc. © 2014 Pearson Education, Inc. 1 2/25/2015 6.1 Classes of Carbohydrates 6.1 Classes of Carbohydrates FIBER IN YOUR DIET FIBER IN YOUR DIET • Dietary fibers are carbohydrates that we cannot digest • Insoluble fibers do not mix with water, although they with our own enzymes.
  • Monosaccharides

    Monosaccharides

    UNIT 5 MONOSACCHARIDES Structure 5.1 Introduction 5.4 Biologically Important Sugar Derivatives Expected Learning Outcomes Sugar Acids 5.2 Overview of Carbohydrates Sugar Alcohols Amino Sugars 5.3 Monosaccharides Deoxy Sugars Linear Structure Sugar Esters Ring Structure Glycosides Conformations 5.5 Summary Stereoisomers 5.6 Terminal Questions Optical Properties 5.7 Answers 5.8 Further Readings 5.1 INTRODUCTION Carbohydrates constitute the most abundant organic molecules found in nature and are widely distributed in all living organisms. These are synthesized in nature by green plants, algae and some bacteria by photosynthesis. They also form major part of our diet and provide us energy required for the life sustaining activities such as growth, metabolism and reproduction. At microscopic level, these constitute the structural components of the cell such as cell membrane and cell wall. In this unit, we shall begin with general overview of the chemical nature of carbohydrates and their classification. The unit focuses mainly on the simplest carbohydrates known as monosaccharides. We shall learn about the chemical structures of different monosaccharides and how to draw them. We shall also discuss their stereochemistry in detail which would help to understand how change in orientation of same substituents results in different molecules with same chemical formula but different properties. We shall also discuss about some of the chemical reactions of monosaccharides resulting in 77 formation of important derivatives and their biological importance.
  • Pentose Phosphate Pathway in Health and Disease: from Metabolic

    Pentose Phosphate Pathway in Health and Disease: from Metabolic

    UNIVERSIDADE DE LISBOA FACULDADE DE FARMÁCIA DEPARTAMENTO DE BIOQUÍMICA PENTOSE PHOSPHATE PATHWAY IN HEALTH AND DISEASE: FROM METABOLIC DYSFUNCTION TO BIOMARKERS Rúben José Jesus Faustino Ramos Orientador: Professora Doutora Maria Isabel Ginestal Tavares de Almeida Mestrado em Análises Clínicas 2013 Pentose Phosphate Pathway in health and disease: From metabolic dysfunction to biomarkers . Via das Pentoses Fosfato na saúde e na doença: Da disfunção metabólica aos biomarcadores Dissertação apresentada à Faculdade de Farmácia da Universidade de Lisboa para obtenção do grau de Mestre em Análises Clínicas Rúben José Jesus Faustino Ramos Lisboa 2013 Orientador: Professora Doutora Maria Isabel Ginestal Tavares de Almeida The studies presented in this thesis were performed at the Metabolism and Genetics group, iMed.UL (Research Institute for Medicines and Pharmaceutical Sciences), Faculdade de Farmácia da Universidade de Lisboa, Portugal, under the supervision of Prof. Maria Isabel Ginestal Tavares de Almeida, and in collaboration with the Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands, Dr. Mirjam Wamelink. De acordo com o disposto no ponto 1 do artigo nº 41 do Regulamento de Estudos Pós- Graduados da Universidade de Lisboa, deliberação nº 93/2006, publicada em Diário da Republica – II série nº 153 – de 5 julho de 2003, o autor desta dissertação declara que participou na conceção e execução do trabalho experimental, interpretação dos resultados obtidos e redação dos manuscritos. Para os meus pais e