Terminology

Alditols - Compounds arising from reduction of a carbonyl group on a sugar.
Aldohexose - A hexose containing an aldehyde group (Figure 9.9a).
Aldonic Acid - Product of mild oxidation of an aldose with alkaline Cu(II) (Fehling's solution).
Aldopentose - A pentose containing an aldehyde group (Figure 9.9a).
Aldose - A monosaccharide containing an aldehyde group.
Aldotetrose - A tetrose containing an aldehyde group (Figure 9.9a).
Aldotriose - A triose containing an aldehyde group (Figure 9.9a).
-L-Fucose - An 'L' sugar often found in the carbohydrate moiety of glycoproteins (Figure 9.29).
Amino Sugars - Compounds formed by adding an amino group to a sugar, most commonly at position 2.
Amygdalin - A toxic glycoside found in the seeds of bitter almonds that yields hydrogen cyanide (HCN) on hydrolysis (Figure 9.15).
Amylopectin - A plant storage polysaccharide composed of a polymer of -D-glucopyranose joined together in (1->4) linkages with branches in the (1->6) configuration (Figure 9.19).
Amylose - A plant storage polysaccharide composed of a polymer of -D-glucopyranose joined exclusively in (1->4) linkages (Figure 9.20).
Anomeric Carbon - The carbon of a newly created center of chirality arising from the cyclization of a sugar (Figure 9.14).
Anomers - Stereoisomers of cyclized monosaccharide molecules differing only in the configuration of the newly created center of chirality arising from the cyclization (Figure 9.14).
Blood Group Antigens - O-linked glycans on the membrane proteins (or lipids) of blood cells (Figure 9.29).
Carbohydrate - Compounds having a structure of the general form, (CH 2O)n, though some exceptions exist, such as molecules containing amino, sulfate, and phosphate groups. Also called saccharides.
Cellulases - A class of enzymes which catalyze cleavage of the (1->4) linkage of cellulose. They are found in bacteria in the the rumen of ruminants, protozoans in the gut of termites, and in many fungi.
Cellulose - A polymer of glucose units joined together in (1->4) linkages (Figure 9.21).
Chiral - With respect to a molecule or other object, the property of being nonsuperimposable on its mirror image. An atom that gives a molecule this characteristic is a carbon with four different substituents (Figure 9.5).
Chitin - A homopolymer of N-acetyl--D-glucosamine. A major structural material in the exoskeletons of arthropods and mollusks.
Chondroitin Sulfate - A glycosaminoglycan in conncective tissue composed of a polymer of the disaccharide [glucuronic acid - (1->3) N-acetyl-galactosamine-6-sulfate] joined together by (1->4) linkages (Figure 9.23).
Conformational Isomers - Different 3-D structures of a molecule. They often arise from molecular constraining processes, such as cyclization (Figures 9.11, 9.13, 9.14).
D-L Nomenclature - A system commonly used by biochemists to partly describe the stereochemical configuration of sugars. Sugars are designated D or L corresponding to the configuration of the chiral carbon farthest from the carbonyl group. The naming convention arose from the fact that most D-sugars rotated polarized light to the right (dextrorotary), whereas most L-sugars rotated polarized light to the left (levorotary).
D-sugars - The preferred stereochemical structure of most biological sugars.
Dermatan Sulfate - A glycosaminoglycan of skin.
Diastereoisomers - Molecules that are stereoisomers but not enantiomers of each other. Isomers that differ in configuration about two or more asymmetric carbon atoms and are not complete mirror images. (Figure 9.14).
Dihydroxyacetone - The only aldo-ketose (Figure 9.3).
Disaccharides - Carbohydrates containing two sugar moieties (Figure 9.16).
Enantiomers - Also called optical isomers, these are stereoisomers that are nonsuperimposable mirror images of each other (Figure 9.5, Figure 9.14).
Enediol - A compound, usually a molecular intermediate, containing hydroxyl groups on both carbons that are joined by a double bond (Figure 9.4).
Fehling's Solution - An alkaline solution of Cu(II) used to oxidize an aldose to an aldonic acid.
Fischer Projection - A convention for representing stereoisomers in a plane. The tetrahedron of bonds on a carbon is represented as a plane cross, where the bonds to the right and left are assumed to be pointing toward the viewer and the bonds to the top and bottom are assumed to be pointing away from the viewer. Projections of monosaccharides are oriented with the carbonyl group at the top; the chiral carbon farthest from the carbonyl group (which is the one that determines whether the sugar is the D or the L form) is then drawn with its hydroxyl to the right for the D form and to the left for the L form (Figure 9.9a).
Formaldehyde - The simplest possible carbohydrate. It is a noxious, poisonous gas.
Furanose - A sugar in a five-membered ring structure (Figure 9.10).
Glucan - A class of homopolymers of -D-glucose, including glycogen, amylose, and amylopectin.
Glucomannan - Plant cell wall polysaccaride. Is a component of hemicellulose.
Glycan - Saccharide chain of a glycoprotein.
Glycocalyx - An extremely thick coating of saccharides on the surface of some animal cells.
Glycogen - An animal storage polysaccharide composed of a polymer of -D-glucopyranose joined together in (1->4) linkages with branches in the (1->6) configuration.
Glycolipid - Class of compounds in which saccharides are linked to membrane lipids. These are are a subclass of blood group antigens.
Glycoproteins - Proteins that carry covalently attached oligosaccharide or polysaccharide chains.
Glycosaminoglycans - A group of polysaccharides in the skin and connective tissue of vertebrate animals. These compounds form a matrix to hold together the protein components of these tissues.
Glycosides - Class of compounds formed by elimination of water between the anomeric hydroxyl of a cyclic monosaccharide and the hydroxyl group of another compound (Figure 9.15).
Gram-negative Bacteria - Bacteria which do not retain the Gram stain (a dye-iodine complex) (Figure 9.25).
Gram-positive Bacteria - Bacteria which retain the Gram stain (a dye-iodine complex) (Figure 9.25).
Haworth Projection - A conventional planar representation of a cyclized monosaccharide molecule. The hydroxyls that are represented to the right of the chain in a Fischer projection are shown below the plane in this projection. (see here).
Hemicellulose - A group of plant cell wall polysaccharides, including xylans, glucomannans, and other polymers.
Heparin - A highly sulfated glycosaminoglycan that acts as a natural anticoagulant. It binds strongly to a blood protein, antiprothrombin III, and the complex inhibits enzymes of the blood clotting process.
Heptose - A sugar containing seven carbons.
Heteropolysaccharide - A polysaccharide composed of non-identical monomeric subunits.
Hexose - A sugar containing six carbons.
Homopolysaccharide - A polysaccharide composed of identical monomeric subunits.
Hyaluronic Acid - A glycosaminoglycan composed of a polymer of the disaccharide [glucuronic acid-(1->3)-N-acetylglucosamine]. Individual disaccharides are joined together by (1->4) linkages (Figure 9.23).
Keratan Sulfate - A glycosaminoglycan in conncective tissue composed of a polymer of the disaccharide [galactose-N-acetyl-6-sulfate-(1->3)-galactose]. Individual disaccharides are joined together in (1->4) linkages (Figure 9.23).
Ketohexose - A hexose containing a ketone group (Figure 9.9b).
Ketopentose - A pentose containing a ketone group (Figure 9.9b).
Ketose - A monosaccharide containing a ketone group.
Ketotetrose - A tetrose containing a ketone group (Figure 9.9b).
Ketotriose - A triose containing a ketone group (Figure 9.9b).
Lactone - A class of compound in equilibrium in solution with free aldonic acids.
Lactose Synthase - Enzyme catalyzing synthesis of lactose from uridine diphosphate (UDP) and galactose (Figure 9.17).
Lectins - A diverse group of saccharide-binding proteins separate from the immunoglobulins.
Lipoteichoic Acid - Elongated lipid-oligosaccharide complexes in the cell walls of Gram-positive bacteria (Figure 9.25).
Lysozymes - Enzymes that attack the peptidoglycan layer of bacterial cell walls.
Monosaccharide - Small monomeric carbohydrate molecules, which include the simple sugars (Table 9.1).
Mucins - Glycoproteins found extensively in salivary secretions that contain many short O-linked glycans.
Mutarotation - The process whereby the configuration of an anomeric carbon of a sugar converts from to or vice-versa.
N-linked Glycan - Saccharide chain in a glycoprotein (usually) attached to the protein via an N-acetylglucosamine or N-acetylgalactosamine residue to an asparagine in the protein (Figure 9.28).
O-linked Glycan - Saccharide chain in a glycoprotein (usually) attached to the protein via N-acetylgalactosamine linkage to the hydroxyl group of threonine or serine. Collagen is an exception in that the linkage is to a hydroxylysine or hydroxylysine (Figure 9.28).
Octose - A sugar containing eight carbons.
Oligosaccharide - Carbohydrate molecules containing a few monomers joined to each other.
Ouabain - A toxic glycoside that inhibits the action of the enzymes that pump sodium and potassium ions across cell walls to maintain necessary electrolyte balance. It comes from an African shrub (Figure 9.15).
Pentose - A sugar containing five carbons (Figure 9.9a, Figure 9.9b).
Peptidoglycan - A polysaccharide-peptide complex found in the cell wall of bacteria. Gram-positive bacteria have a multilayered complex, whereas Gram-negative bacteria have only a single layer (Figure 9.25).
Photosynthesis - Process by which plants take up carbon dioxide and 'fix' it into carbohydrates.
Polysaccharide - Long polymers of the monomeric carbohydrate molecules (Figure 9.19).
Proteoglycan Complex - A protein-carbohydrate complex in cartilage in which the filamentous structure is built on a single long hyaluronic acid molecule to which extended core proteins are attached covalently (Figure 9.24).
Pyranose - A sugar in a six-member ring structure (Figure 9.10).
R-S Nomenclature - A system to describe the absolute stereochemical configuration of an enantiomer. It relies on prioritizing the chemical groups attached to the asymmetric carbon (Figure 9.6).
Saccharide - Compounds having a structure of the general form, (CH 2O)n, though some exceptions exist, such as molecules containing amino, sulfate, and phosphate groups. Also called carbohydrates.
Sedoheptulose - Important heptose in the pentose phosphate pathway.
Sialic Acid - A modified sugar residue found in glycoproteins. In blood, when this residue is cleaved, the body recognizes the glycoprotein as aged and destroys it. Also known as N-Acetylneuraminic Acid (Figure 9.29).
Starch - A plant storage polysaccharide composed of a mixture of amylose and amylopectin.
Stereoisomers - Molecules containing a center of asymmetry that can exist in different 3D isomeric forms.
Tautomers - Structural isomers differing in the location of their hydrogens and double bonds.
Tetrose - A sugar containing four carbons (Figure 9.9a, Figure 9.9b).
Triose - A sugar containing three carbons (Figure 9.9a, Figure 9.9b).
Xylans - Polysaccharides in plant cell walls which are polymers of -D-xylopyranose units linked in the (1->4) configuration. Substituent groups are often attached.