DOCSLIB.ORG

Carbohydrates: Disaccharides and Polysaccharides

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Carbohydrates: Disaccharides and Polysaccharides Carbohydrates: Disaccharides and Polysaccharides Disaccharides Linkage of the anomeric carbon of one monosaccharide to the OH of another monosaccharide via a condensation reaction. The bond is termed a glycosidic bond. The end of the disaccharide that contains the anomeric carbon is referred to as the reducing end because it is capable of reducing various metal ions. Formation of a glycosidic bond between two glucose molecules. Nomenclature: To describe disaccharides you need to specify the following: 1. The names of the two monosaccharides. 2. How they are linked together (one anomeric is always used). 3. The configuration of the anomeric carbons on both monosaccharides. The Six Simple Rules for Naming Disaccharides are as follows: 1. The non-reducing end defines the first sugar. 2. Configuration of the anomeric carbon of the 1st sugar (α,β). 3. Name of 1st monosaccharide, root name followed by pyranosyl (6- ring) or furanosyl (5-ring). 4. Atoms which are linked together, 1st sugar then 2nd sugar. 5. Configuration of the anomeric carbon of the second sugar (α,β) (often omitted if the anomeric carbon is free since α and β forms are in equilibrium.) 6. Name of 2nd monosaccharide, root name followed by pyranose (6- ring) or furanose (5-ring) (If both anomeric carbons are involved, then the name ends in ‘oside”, not ‘ose’) Example: Sucrose (table sugar): The anomeric carbon of glucose forms a bridge to the anomeric carbon of fructose. Since there is no reducing end, either sugar can be used to begin the name. Sucrose, drawn in two different ways. Note that both anomeric carbons are involved in the glycosidic linkage, thus both conformations have to be specified. Example: Lactose (sugar in mammalian milk): Galactose and glucose are linked together. Note the alternative way to indicate the β linkage in the right-hand drawing. Since the reducing end is free, and can interconvert between α and β forms, it is not necessary to specify the configuration of the anomeric carbon on the glucose. Lactose, drawn in two different ways. The anomeric carbon on galactose is involved in the β glycosidic linkage; consequently its configuration has to be specified. The anomeric carbon on the reducing end (glucose) can be in either configuration; the α configuration is represented here. Polysaccharides Polysaccharides are many monosaccharides linked by glycosidic bonds. Most poly-saccharides are polymers of either glucose, or modified glucose. They play important roles in the structure of plants (cellulose) as well as energy storage in both plants (starch) and animals (glycogen). Nomenclature: : In the case of homo-polymers, the short-hand notation is to simply describe the linkage between the glucose units: both the conformation of the anomeric carbon and the carbons participating in the glycosidic bond, i.e. "β (1-4) glucose" instead of "β- glucopyranosyl (1-4) β glucopyranose." Release of glucose from glycogen/amylopectin: Glucose units are released from non-reducing end by the enzyme glycogen phosphorylase, producing glucose-1-phosphate (G-1-P). G-1-P is used to generate energy by entering glycolysis. Release of glucose-1-phosphate from glycogen. The glucose is released from the non-reducing end. Structural Polysaccharides 1. Cellulose: Structural polysaccharide of plants. 1. Mammalian enzymes can’t digest β 1-4 glucose. 2. Similar in structure to β-sheets in proteins: forms flat sheets with multiple hydrogen bonds between strands. 3. Digested by symbiotic microorganisms (such as those in termites). Cellulose. The left and right diagrams are both of cellulose; they differ in how the β linkage is drawn. Hydrogen bonded networks in cellulose forms a stable sheet-like structure. 2. Bacterial Cell Walls: 1. Polysaccharide chains of alternating N-acetylglucose amine (NAG) and N-acetylmuraminc acid (NAM) 2. Muramic acid on NAM linked to a small peptide (L-Ala D-Gln L-Lys D-Ala). One of the few places in biochemistry where D-amino acids are found. 3. NAM peptide chains are crosslinked with pentaglycine bridges that extend off of terminal Ala and join to L-Lys sidechain on adjacent chain, forming a tough crosslinked cell wall. 4. A structure that has covalent interactions between the carbohydrate chains and the protein chains is called a peptido-glycan 5. Synthesis of bacterial cell walls is inhibited by penicillin. Bacterial Cell Wall. This peptido-glycan consists of linear polysaccharides, which consist of alternating NAM and NAG residues, covalently crosslinked by peptide chains. Left image is the molecular structure; the right image shows how a number of carbohydrate strands are linked together. .
Load more

Recommended publications
  • Oat Β-Glucan Lowers Total and LDL-Cholesterol
    Oat β-glucan lowers total and LDL-cholesterol Sylvia Pomeroy, Richard Tupper, Marja Cehun-Aders and Paul Nestel Abstract Several soluble polysaccharides have been shown to daily, have shown to significantly lower serum cholesterol have cholesterol-lowering properties and to have a role in pre- mostly by between 5.4 and 12.8% and LDL-cholesterol by vention of heart disease. Major sources of one such between 8.5 and 12.4% in moderately hypercholesterolae- β polysaccharide ( -glucan) are oats and barley. The aim of this mic subjects. Larger reductions have been reported (8–13) study was to examine the effects on plasma lipid concentrations whereas other well executed trials have proven to be when β-glucan derived from a fractionated oat preparation was consumed by people with elevated plasma lipids. A single-blind, negative (14–18). crossover design compared plasma cholesterol, triglycerides, Two meta-analysis studies have shed more informa- high density lipoproteins and low density lipoproteins (LDLs) in β tion on this issue. One meta-analysis (19) of 23 trials 14 people; in the order of low, high and low -glucan supple- provided strong support that approximately 3 g of soluble mented diets, each of three weeks duration. For the high β- glucan diet, an average intake of 7 g per day was consumed from fibre from oat products per day can lower total cholesterol cereal, muffins and bread. The background diet remained rela- concentrations from 0.13 to 0.16 mmol/L and concluded tively constant over the three test periods. Differences during the that the reduction was greater in those with higher initial interventions were calculated by one-way repeated measures cholesterol concentrations.
    [Show full text]
  • Sweeteners Georgia Jones, Extension Food Specialist
    ® ® KFSBOPFQVLCB?O>PH>¨ FK@LIKUQBKPFLK KPQFQRQBLCDOF@RIQROB>KA>QRO>IBPLRO@BP KLTELT KLTKLT G1458 (Revised May 2010) Sweeteners Georgia Jones, Extension Food Specialist Consumers have a choice of sweeteners, and this NebGuide helps them make the right choice. Sweeteners of one kind or another have been found in human diets since prehistoric times and are types of carbohy- drates. The role they play in the diet is constantly debated. Consumers satisfy their “sweet tooth” with a variety of sweeteners and use them in foods for several reasons other than sweetness. For example, sugar is used as a preservative in jams and jellies, it provides body and texture in ice cream and baked goods, and it aids in fermentation in breads and pickles. Sweeteners can be nutritive or non-nutritive. Nutritive sweeteners are those that provide calories or energy — about Sweeteners can be used not only in beverages like coffee, but in baking and as an ingredient in dry foods. four calories per gram or about 17 calories per tablespoon — even though they lack other nutrients essential for growth and health maintenance. Nutritive sweeteners include sucrose, high repair body tissue. When a diet lacks carbohydrates, protein fructose corn syrup, corn syrup, honey, fructose, molasses, and is used for energy. sugar alcohols such as sorbitol and xytilo. Non-nutritive sweet- Carbohydrates are found in almost all plant foods and one eners do not provide calories and are sometimes referred to as animal source — milk. The simpler forms of carbohydrates artificial sweeteners, and non-nutritive in this publication. are called sugars, and the more complex forms are either In fact, sweeteners may have a variety of terms — sugar- starches or dietary fibers.Table I illustrates the classification free, sugar alcohols, sucrose, corn sweeteners, etc.
    [Show full text]
  • 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.
    [Show full text]
  • An Overview of Non Starch Polysaccharide
    JOURNAL OF ANIMAL NUTRITION AND PHYSIOLOGY Journal homepage: www.jakraya.com/journal/janp MINI-REVIEW An Overview of Non Starch Polysaccharide Kamdev Sethy a, S.K. Mishra b, P. P. Mohanty c, J. Agarawal c, P. Meher c, D. Satapathy c, J. K. Sahoo c, S. Panda c and S. M. Nayak c aAssistant Professor, bAssociate Professor, cM.V.Sc. Scholars, Department of Animal Nutrition, College of Veterinary Science and Animal Husbandry, Orissa University of Agriculture and Technology, Bhubaneswar, India. Abstract Polysaccharides are macromolecules of monosaccharides linked by *Corresponding Author: glycosidic bonds. Polysaccharides are widespread biopolymers, which Dr. Kamdev Sethy quantitatively represent the most important group of nutrients in feed. These are major components of plant materials used in rations for E mail: [email protected] monogastrics. Non-starch polysaccharides (NSP) contain ß-glucans, cellulose, pectin and hemicellulose. NSP consist of both soluble and insoluble fractions. Soluble NSP of cereals such as wheat, barley and rye increases intestinal viscosity there by interfere with the digestive processes Received: 05/02/2015 and exert strong negative effects on net utilisation of energy. NSP cannot be degraded by endogeneous enzymes and therefore reach the colon almost Revised: 27/02/2015 indigested. Insoluble NSP make up the bulk in the diets. NSP are known to posses anti-nutritional properties by either encapsulating nutrients and/or Accepted: 02/03/2015 depressing overall nutrient digestibility through gastro-intestinal modifications. Key words: Polysaccharides, Starch, Digestibility. 1. Introduction xylans are present only in the hull and husk portion. Non starch polysaccharides (NSPs) are The cotyledon of legumes contains pectic carbohydrate fractions excluding starch and free sugars.
    [Show full text]
  • Carbohydrates Adapted from Pellar
    Carbohydrates Adapted from Pellar OBJECTIVE: To learn about carbohydrates and their reactivities BACKGROUND: Carbohydrates are a major food source, with most dietary guidelines recommending that 45-65% of daily calories come from carbohydrates. Rice, potatoes, bread, pasta and candy are all high in carbohydrates, specifically starches and sugars. These compounds are just a few examples of carbohydrates. Other carbohydrates include fibers such as cellulose and pectins. In addition to serving as the primary source of energy for the body, sugars play a number of other key roles in biological processes, such as forming part of the backbone of DNA structure, affecting cell-to-cell communication, nerve and brain cell function, and some disease pathways. Carbohydrates are defined as polyhydroxy aldehydes or polyhydroxy ketones, or compounds that break down into these substances. They can be categorized according to the number of carbons in the structure and whether a ketone or an aldehyde group is present. Glucose, for example, is an aldohexose because it contains six carbons and an aldehyde functional group. Similarly, fructose would be classified as a ketohexose. glucose fructose A more general classification scheme exists where carbohydrates are broken down into the groups monosaccharides, disaccharides, and polysaccharides. Monosaccharides are often referred to as simple sugars. These compounds cannot be broken down into smaller sugars by acid hydrolysis. Glucose, fructose and ribose are examples of monosaccharides. Monosaccharides exist mostly as cyclic structures containing hemiacetal or hemiketal groups. These structures in solution are in equilibrium with the corresponding open-chain structures bearing aldehyde or ketone functional groups. The chemical linkage of two monosaccharides forms disaccharides.
    [Show full text]
  • Nucleosides & Nucleotides
    Nucleosides & Nucleotides Biochemistry Fundamentals > Genetic Information > Genetic Information NUCLEOSIDE AND NUCLEOTIDES SUMMARY NUCLEOSIDES  • Comprise a sugar and a base NUCLEOTIDES  • Phosphorylated nucleosides (at least one phosphorus group) • Link in chains to form polymers called nucleic acids (i.e. DNA and RNA) N-BETA-GLYCOSIDIC BOND  • Links nitrogenous base to sugar in nucleotides and nucleosides • Purines: C1 of sugar bonds with N9 of base • Pyrimidines: C1 of sugar bonds with N1 of base PHOSPHOESTER BOND • Links C3 or C5 hydroxyl group of sugar to phosphate NITROGENOUS BASES  • Adenine • Guanine • Cytosine • Thymine (DNA) 1 / 8 • Uracil (RNA) NUCLEOSIDES • =sugar + base • Adenosine • Guanosine • Cytidine • Thymidine • Uridine NUCLEOTIDE MONOPHOSPHATES – ADD SUFFIX 'SYLATE' • = nucleoside + 1 phosphate group • Adenylate • Guanylate • Cytidylate • Thymidylate • Uridylate Add prefix 'deoxy' when the ribose is a deoxyribose: lacks a hydroxyl group at C2. • Thymine only exists in DNA (deoxy prefix unnecessary for this reason) • Uracil only exists in RNA NUCLEIC ACIDS (DNA AND RNA)  • Phosphodiester bonds: a phosphate group attached to C5 of one sugar bonds with - OH group on C3 of next sugar • Nucleotide monomers of nucleic acids exist as triphosphates • Nucleotide polymers (i.e. nucleic acids) are monophosphates • 5' end is free phosphate group attached to C5 • 3' end is free -OH group attached to C3 2 / 8 FULL-LENGTH TEXT • Here we will learn about learn about nucleoside and nucleotide structure, and how they create the backbones of nucleic acids (DNA and RNA). • Start a table, so we can address key features of nucleosides and nucleotides. • Denote that nucleosides comprise a sugar and a base.
    [Show full text]
  • Oat Beta Glucans
    Oat beta glucans Oat bran is produced by removing the starchy content of the grain. It is rich in dietary fibers, especially in soluble fibers, present in the inner periphery of the kernel. Oats contain more soluble fibers than any other grain, resulting in slower digestion and an extended sensation of fullness, among other things. Oat is a rich source of the water-soluble fiber (1,3/1,4) β-glucan, and its effects on health have been extensively studied over the last 30 years. Oat β-glucans can be highly concentrated in different types of oat brans. The beta glucan content varies, from 3-5% depending on variety when it grows in the field. Rolled oat/oat flakes is about 4% and also wholemeal oat flour about 4%. With Swedish Oat Fiber’s specially developed fractionating process, we can do concentrations of beta glucans from 6% up to 32%. Beta-D-glucans, usually referred to as beta glucans, comprise a class of indigestible polysaccharides widely found in nature in sources such as grains, barley, yeast, bacteria, algae and mushrooms. In oats, they are concentrated in the bran, more precisely in the aleurone and sub-aleurone layer (see picture above). Oat beta glucan is a natural soluble fiber. It is a viscous polysaccharide made up of units of the monosaccharide D-glucose. Oat beta glucan is composed of mixed-linkage polysaccharides. This means the bonds between the D-glucose units are either beta-(1 →3) linkages or beta-(1 →4) linkages. This type of beta-glucan is also referred to as a mixed- linkage (1 →3), (1 →4)-beta-D-glucan.
    [Show full text]
  • 8| Nucleotides and Nucleic Acids
    8| Nucleotides and Nucleic Acids © 2013 W. H. Freeman and Company CHAPTER 8 Nucleotides and Nucleic Acids Key topics: – Biological function of nucleotides and nucleic acids – Structures of common nucleotides – Structure of double‐stranded DNA – Structures of ribonucleic acids – Denaturation and annealing of DNA – Chemistry of nucleic acids; mutagenesis Functions of Nucleotides and Nucleic Acids • Nucleotide Functions: – Energy for metabolism (ATP) – Enzyme cofactors (NAD+) –Signal transduction (cAMP) • Nucleic Acid Functions: – Storage of genetic info (DNA) – Transmission of genetic info (mRNA) –Processing of genetic information (ribozymes) –Protein synthesis (tRNA and rRNA) Nucleotides and Nucleosides • Nucleotide = – Nitrogeneous base –Pentose – Phosphate • Nucleoside = – Nitrogeneous base –Pentose • Nucleobase = – Nitrogeneous base Phosphate Group •Negatively charged at neutral pH • Typically attached to 5’ position – Nucleic acids are built using 5’‐triphosphates •ATP, GTP, TTP, CTP – Nucleic acids contain one phosphate moiety per nucleotide •May be attached to other positions Other Nucleotides: Monophosphate Group in Different Positions Pentose in Nucleotides • ‐D‐ribofuranose in RNA • ‐2’‐deoxy‐D‐ribofuranose in DNA •Different puckered conformations of the sugar ring are possible Nucleobases •Derivatives of pyrimidine or purine • Nitrogen‐containing heteroaromatic molecules •Planar or almost planar structures •Absorb UV light around 250–270 nm Pyrimidine Bases • Cytosine is found in both DNA and RNA •Thymineis found only in DNA
    [Show full text]
  • Structure and Metabolism of the Intracellular Polysaccharide of Corynebacterium. Don D
    Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1969 Structure and Metabolism of the Intracellular Polysaccharide of Corynebacterium. Don D. Mickey Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Mickey, Don D., "Structure and Metabolism of the Intracellular Polysaccharide of Corynebacterium." (1969). LSU Historical Dissertations and Theses. 1679. https://digitalcommons.lsu.edu/gradschool_disstheses/1679 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. This dissertation has been microfilmed exactly as received 70-9079 MICKEY, Don D., 1940- STRUCTURE AND METABOLISM OF THE INTRACELLULAR POLYSACCHARIDE OF CORYNEBACTERIUM. The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1969 Microbiology University Microfilms, Inc., Ann Arbor, Michigan STRUCTURE AND METABOLISM OF THE INTRACELLULAR POLYSACCHARIDE OF CORYNEBACTERIUM A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Microbiology by Don D. Mickey B. S., Louisiana State University, 1963 August, 1969 ACKNOWLEDGMENT The author wishes to acknowledge Dr. M. D. Socolofsky for his guidance during the preparation of this dissertation. He also wishes to thank Dr. H. D. Braymer and Dr. A. D. Larson and other members of the Department of Microbiology for helpful advice given during various phases of this research.
    [Show full text]
  • Nucleotides and Nucleic Acids
    CHAPTER 8 Nucleotides and Nucleic Acids Functions of Nucleotides and Nucleic Acids • Nucleotide Functions: – Energy for metabolism (ATP) – Enzyme cofactors (NAD+) – Signal transduction (cAMP) • Nucleic Acid Functions: – Storage of genetic info (DNA) – Transmission of genetic info (mRNA) – Processing of genetic information (ribozymes) – Protein synthesis (tRNA and rRNA) Nucleotides and Nucleosides • Nucleotide = – Nitrogeneous base – Pentose – Phosphate • Nucleoside = – Nitrogeneous base – Pentose • Nucleobase = – Nitrogeneous base Phosphate Group • Negatively charged at neutral pH • Typically attached to 5’ position – Nucleic acids are built using 5’- triphosphates • ATP, GTP, TTP, CTP – Nucleic acids contain one phosphate moiety per nucleotide • May be attached to other positions Other Nucleotides: Monophosphate Group in Different Positions Pentose in Nucleotides • -D-ribofuranose in RNA • -2’-deoxy-D-ribofuranose in DNA • Different puckered conformations of the sugar ring are possible Purine Bases • Adenine and guanine are found in both RNA and DNA • Also good H-bond donors and acceptors • Adenine pKa at N1 is 3.8 • Guanine pKa at N7 is 2.4 • Neutral molecules at pH 7 • Derivatives of pyrimidine or purine • Nitrogen-containing heteroaromatic molecules • Planar or almost planar structures • Absorb UV light around 250–270 nm Pyrimidine Bases • Cytosine is found in both DNA and RNA • Thymine is found only in DNA • Uracil is found only in RNA • All are good H-bond donors and acceptors • Cytosine pKa at N3 is 4.5 • Thymine pKa at N3 is 9.5
    [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]
  • Impact of Glycosidic Bond Configuration on Short Chain Fatty
    nutrients Article Impact of Glycosidic Bond Configuration on Short Chain Fatty Acid Production from Model Fermentable Carbohydrates by the Human Gut Microbiota Hannah C. Harris 1,2, Christine A. Edwards 1 and Douglas J. Morrison 2,* 1 School of Medicine, Dentistry and Nursing, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow G31 2ER, UK; [email protected] (H.C.H.); [email protected] (C.A.E.) 2 Scottish Universities Environmental Research Centre, University of Glasgow, Glasgow G75 0QF, UK * Correspondence: [email protected]; Tel.: +44-135-527-0134 Received: 17 October 2016; Accepted: 22 December 2016; Published: 1 January 2017 Abstract: Short chain fatty acids (SCFA) are the major products of carbohydrate fermentation by gut bacteria. Different carbohydrates are associated with characteristic SCFA profiles although the mechanisms are unclear. The individual SCFA profile may determine any resultant health benefits. Understanding determinants of individual SCFA production would enable substrate choice to be tailored for colonic SCFA manipulation. To test the hypothesis that the orientation and position of the glycosidic bond is a determinant of SCFA production profile, a miniaturized in vitro human colonic batch fermentation model was used to study a range of isomeric glucose disaccharides. Diglucose α(1-1) fermentation led to significantly higher butyrate production (p < 0.01) and a lower proportion of acetate (p < 0.01) compared with other α bonded diglucoses. Diglucose β(1-4) also led to significantly higher butyrate production (p < 0.05) and significantly increased the proportions of propionate and butyrate compared with diglucose α(1-4) (p < 0.05).
    [Show full text]