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Varki A, Cummings RD, Esko JD, et al., editors. Essentials of Glycobiology [Internet]. 3rd edition. Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press; 2015-2017. doi: 10.1101/glycobiology.3e.061
Essentials of Glycobiology [Internet]. 3rd edition.
Show details- ABO
Gene locus comprising three major allelic glycosyltransferases that generate the A, B, and O blood groups.
- Acetal
An organic compound derived from a hemiacetal by reaction with an alcohol. If the hemiacetal is a sugar, the acetal is a glycoside.
- Adhesin
A protein on the surface of bacteria, viruses, or parasites that binds to a ligand present on the surface of a host cell.
- Affinity
A measure of the strength of interaction between a receptor and its ligand.
- Agglutination
The clumping of cells in the presence of a protein (e.g., antibody or lectin). The related term hemagglutination denotes the specific case wherein the cells are red blood cells.
- Aglycone
Non-carbohydrate portion of a glycoconjugate or glycoside that is glycosidically linked to the glycan through the reducing terminal sugar.
- Aldose
A monosaccharide with an aldehyde group or potential aldehydic carbonyl group (by definition, this is the C-1 position).
- Amino sugar
A monosaccharide in which an alcoholic hydroxyl group is replaced by an amino group.
- Anomeric carbon
The carbon atom of a monosaccharide that bears the hemiacetal functionality (C-1 for most sugars; C-2 for sialic acids).
- Anomers
Stereoisomers of a monosaccharide that differ only in configuration at the anomeric carbon of the ring structure.
- Antenna
A branch of an oligosaccharide emanating from a “core” structure.
- Arixtra
See Fondaparinux.
- Asparagine-linked oligosaccharide
See N-glycan.
- Avidity
A measure of the combined strength of interaction from the multiple affinities of a multivalent complex.
- Azide
A functional group comprising three nitrogen atoms bound in a linear arrangement (N3).
- Azido sugar
A monosaccharide to which an azido group has been introduced synthetically.
- Bactoprenol
See Undecaprenol.
- Beta elimination
The cleavage of a C-O or C-N bond positioned on the beta carbon with respect to a carbonyl group. The process is used to cleave O-glycans from Ser or Thr residues.
- Biofilm
Community of bacteria that adheres to a moist surface (e.g., surface of ponds or teeth).
- C-type Lectins
A class of Ca++-dependent lectins recognizable by a characteristic sequence comprising their carbohydrate recognition domain.
- Calnexin
Membrane-bound protein chaperone that mediates quality control of protein folding in the endoplasmic reticulum.
- Calreticulin
Soluble protein chaperone that mediates quality control of protein folding in the endoplasmic reticulum.
- Capillary electrophoresis (CE)
An analytical technology using high voltage across the span of a small-diameter capillary to accomplish separation. It is applicable to small quantities of carbohydrates and can interface with a mass spectrometer.
- Capsule
A protective extracellular polysaccharide coat surrounding certain bacteria. Presence of a capsular polysaccharide is often associated with virulence.
- Carbohydrate
A generic term used interchangeably in this book with sugar, saccharide, or glycan. Includes monosaccharides, oligosaccharides, and polysaccharides, as well as derivatives of these compounds.
- Carbohydrate-recognition domain (CRD)
The domain of a polypeptide that is specifically involved in binding to carbohydrate; in lectins, often a highly evolutionarily conserved region of the polypeptide.
- Cassette
A glycosylated amino acid used in solid-phase peptide synthesis to generate glycopeptides.
- CAZy database
Denoting “Carbohydrate Active enZYmes,” this database describes the families of structurally related catalytic and carbohydrate-binding modules (or functional domains) of enzymes that degrade, modify, or create glycosidic bonds.
- Cellulose
A repeating homopolymer of β1-4-linked glucose residues.
- Ceramide
The common lipid component of glycosphingolipids, composed of a long-chain amino alcohol (sphingosine) and an amide-linked fatty acid.
- Cerebroside
A glycolipid composed of ceramide with an attached galactose (galactosylceramide) or glucose (glucosylceramide).
- Chemical shift
A term referring to the position of a resonance in an NMR spectrum.
- Chemoenzymatic synthesis
Glycan synthesis that uses both chemical and enzymatic transformations to obtain the desired product.
- Chitin
A repeating homopolymer of β1-4-linked N-acetylglucosamine residues; the main component of the cell walls of fungi and the exoskeletons of arthropods, among other functions.
- Chondroitin sulfate
A type of glycosaminoglycan defined by the disaccharide unit (GalNAcβ1-4GlcAβ1-3)n, modified with ester-linked sulfate at certain positions and typically found covalently linked to a proteoglycan core protein.
- Congenital disorder of glycosylation
An inheritable genetic disorder in which mutations have led to improper assembly of glycans, primarily N-glycans.
- Conjugate vaccine
A vaccine consisting of an antigen (frequently a glycan) coupled to a carrier protein.
An NMR technique producing a two-dimensional map of connections, usually between vicinal protons. Useful in assignment of spectra and identification of carbohydrate residues.
- Cryo-electron-microscopy (cryo-EM)
An imaging technique capable of providing near-atomic level resolution for three-dimensional structures of glycan-binding proteins in frozen noncrystalline preparations.
- Deoxy sugar
A monosaccharide in which an alcoholic hydroxyl group is replaced by a hydrogen atom.
- Dermatan sulfate
A modified form of chondroitin sulfate in which a portion of the D-glucuronate residues are epimerized to L-iduronates.
- Dolichol
A terminally saturated polyisoprenoid lipid carrier utilized during the assembly of N-glycans and GPI anchors and the O- and C-mannosylation of proteins in the endoplasmic reticulum.
- Electron transfer dissociation (ETD)
A mass spectrometry fragmentation and ionization technique useful in determining sites of glycosylation on peptides and proteins.
- Electrospray ionization (ESI)
A commonly used method for producing charged species for mass spectrometry analysis.
- Endoglycosidase
An enzyme that catalyzes the cleavage of an internal glycosidic linkage in an oligosaccharide or polysaccharide.
- Endotoxin
See Lipid A.
- Epidermal growth factor (EGF)-like repeats
Small protein motifs (∼40 amino acids) with six conserved cysteine residues that form three disulfide bonds. These often serve as sites for glycan modification.
- Epimerase
An enzyme that catalyzes racemization of a chiral center in a sugar.
- Epimers
Two isomeric monosaccharides differing only in the configuration of a single chiral carbon. For example, mannose is the C-2 epimer of glucose.
- Epitope
The part of a molecule that is recognized by a specific antibody or receptor.
- Erythropoietin
A circulating glycosylated cytokine used to treat anemias.
- Exoglycosidase
An enzyme that cleaves a monosaccharide from the outer (nonreducing) end of an oligosaccharide, polysaccharide, or glycoconjugate.
- Exotoxins
Heat-labile, proteinaceous toxins secreted by bacteria that cause illness.
- Expressed protein ligation (EPL)
A method for generating semisynthetic proteins by the condensation of a synthetic peptide and a recombinant protein. Glycoproteins can be generated by condensation of a synthetic glycopeptide and a recombinant protein.
- Extracellular matrix
A complex array of secreted molecules including glycoproteins, proteoglycans, and/or polysaccharides and structural proteins. In plants, the extracellular matrix is also referred to as the cell wall.
- Extrinsic glycan-binding proteins
Receptors that recognize glycans from a different organism and consist mostly of pathogenic microbial adhesins, agglutinins, or toxins.
- Fimbrae
Proteinaceous fiber-like appendages found in many Gram-negative bacteria.
- Fischer Projection
A two-dimensional representation of a three-dimensional organic molecule devised by Hermann Emil Fischer.
- Fluorophore assisted carbohydrate electrophoresis (FACE)
A technology that combines glycan derivatization and gel electrophoresis for the analysis of small quantities of carbohydrates.
- Fondaparinux
A synthetic heparin (also called Arixtra) used as an anticoagulant.
- Fringe
Family of proteins that modify Notch activity by catalyzing the transfer of N-acetylglucosamine from UDP-GlcNAc to fucose on an EGF-like repeat.
- Furanose
Five-membered (four carbons and one oxygen, i.e., an oxygen heterocycle) ring form of a monosaccharide named after the structurally similar compound furan.
- Galectins
S-type (sulfhydryl-dependent) β-galactoside-binding lectins, usually occurring in a soluble form, expressed by a wide variety of animal cell types and distinguishable by the amino acid sequence of their carbohydrate recognition domains.
- Ganglioside
Anionic glycosphingolipid containing one or more residues of sialic acid.
- Gene chip
A DNA microarray used to quantify transcript levels in high-throughput format.
- Genome
The complete genetic sequence of one set of chromosomes.
- Glycan
A generic term for any sugar or assembly of sugars, in free form or attached to another molecule, used interchangeably in this book with saccharide or carbohydrate.
- Glycan array
A collection of glycans attached to a surface in a spatially addressed manner.
- Glycan-binding proteins
Proteins that recognize and bind to specific glycans and mediate their biological function. See Lectin and Glycosaminoglycan-binding protein.
- Glycation
The nonenzymatic, chemical modification of proteins by addition of carbohydrate, usually through a Schiff-base reaction with the amino group of the side chain of lysine and subsequent Amadori rearrangement to give a stable conjugate. Not to be confused with (enzymatic) glycosylation.
- Glycobiology
Study of the structure, chemistry, biosynthesis, and biological functions of glycans and their derivatives.
- Glycoengineering
Altering the biosynthetic machinery for glycoconjugates in a given cell for the production of defined glycoconjugates.
- Glycocalyx
The cell coat consisting of glycans and glycoconjugates surrounding animal cells that is seen as an electron-dense layer by electron microscopy.
- Glycoconjugate
A molecule in which one or more glycan units are covalently linked to a noncarbohydrate entity.
- Glycoforms
Different molecular forms of a glycoprotein, resulting from variable glycan structure and/or glycan attachment site occupancy.
- Glycogen
A polysaccharide comprising α1-4 and α1-6-linked glucose residues that functions in short-term energy storage in animals; sometimes referred to as animal starch.
- Glycogenin
A protein that acts as a primer for glycogen synthesis.
- Glycolipid
General term denoting a molecule containing a saccharide linked to a lipid aglycone. In higher organisms, most glycolipids are glycosphingolipids, but glycoglycerolipids and other types exist.
- Glycome
The total collection of glycans synthesized by a cell, tissue, or organism under specified conditions of time, space, and environment.
- Glycomics
Systematic analysis of the glycome.
- Glycomimetics
Noncarbohydrate compounds that mimic the properties of saccharides.
- Glycone
Carbohydrate component of a glycoconjugate.
- Glycopeptide
A peptide having one or more covalently attached glycan.
- Glycoprotein
A protein with one or more covalently bound glycan.
- Glycoproteomics
The systems-level analysis of glycoproteins, including their protein identities, sites of glycosylation, and glycan structures.
- Glycosaminoglycans
Polysaccharide side-chains of proteoglycans or free complex polysaccharides composed of linear disaccharide repeating units, each composed of a hexosamine and a hexose or a hexuronic acid (see Heparin, Heparan sulfate, Chondroitin sulfate, Dermatan sulfate, and Hyaluronan).
- Glycosaminoglycan-binding proteins
Proteins that recognize and bind to specific glycosaminoglycans.
- Glycosidase
An enzyme that catalyzes the hydrolysis of glycosidic bonds in a glycan. See Exoglycosidase and Endoglycosidase.
- Glycoside
A glycan containing at least one glycosidic linkage to another glycan or an aglycone.
- Glycosidic linkage
Linkage of a monosaccharide to another residue via the anomeric hydroxyl group. The linkage generally results from the reaction of a hemiacetal with an alcohol (e.g., a hydroxyl group on another monosaccharide or amino acid) to form an acetal. Glycosidic linkages between two monosaccharides have defined regiochemistry and stereochemistry.
- Glycosphingolipid
Glycolipid containing a glycan glycosidically attached to the primary hydroxyl group of ceramide.
- Glycosyl acceptor
The nucleophile in a glycosylation reaction, usually containing a free hydroxyl group.
- Glycosyl donor
The electrophile in a glycosylation reaction; the nucleotide sugar in an enzymatic glycosylation reaction.
- Glycosylation
The enzyme-catalyzed covalent attachment of a carbohydrate to a polypeptide, lipid, polynucleotide, carbohydrate, or other organic compound, generally catalyzed by glycosyltransferases, utilizing specific sugar nucleotide donor substrates.
- Glycosylphosphatidylinositol (GPI) anchor
A membrane anchor that consists of a glycan bridge between phosphatidylinositol and a phosphoethanolamine in amide linkage to the carboxyl terminus of a protein.
- Glycosyltransferase
Enzyme that catalyzes transfer of a sugar from a sugar nucleotide donor to a substrate.
- Hapten
A small glycan that competes with a more complex ligand for binding to a lectin. More generally, any small molecule that interacts with a receptor or antibody.
- Haworth projection
A representation of monosaccharides wherein the cyclic structures are depicted as planar rings with the hydroxyl groups orientated above or below the plane of the ring.
- Hemagglutination
The clumping of red blood cells in the presence of a protein (e.g., antibody or lectin).
- Hemagglutinin
A lectin that recognizes carbohydrates on the surface of red blood cells and causes hemagglutination.
- Hemiacetal
A compound formed by reaction of an aldehyde with an alcohol group, as in ring closure of an aldose.
- Hemiketal
A compound formed by reaction of a ketone with an alcohol group, as in ring closure of a ketose.
- Heparan sulfates
Glycosaminoglycans defined by the disaccharide unit (GlcNAcα1- 4GlcAβ1-4/IdoAα1-4)n, containing N- and O-sulfate esters at various positions, and typically found covalently linked to a proteoglycan core protein.
- Heparin
A type of heparan sulfate made by mast cells that has the highest amount of iduronic acid and of N- and O-sulfate residues. Pharmaceutical heparin binds and activates antithrombin.
- Heteronuclear single quantum coherence (HSQC)
An NMR technique producing a two-dimensional map correlating chemical shifts of heteronuclei (usually 13C for carbohydrates) and chemical shifts of directly bonded protons.
- Heteropolysaccharide
A polysaccharide containing more than one type of monosaccharide.
- Hexosamine
Hexose with an amino group in place of the hydroxyl group at the C-2 position. Common examples found in vertebrate glycans are the N-acetylated sugars, N-acetylglucosamine and N-acetylgalactosamine.
- Hexose
A 6-carbon monosaccharide typically with an aldehyde (or potential aldehyde) at the C-1 position (aldohexose) and hydroxyl groups at all other positions. Common examples in vertebrate glycans are mannose, glucose, and galactose.
- High pressure liquid chromatography (HPLC)
A separation technique frequently used to isolate glycans for analysis or subsequent study.
- Homopolysaccharide
A polysaccharide composed of only one type of monosaccharide.
- Hyaluronan
A glycosaminoglycan defined by the disaccharide unit (GlcNAcβ1-4GlcAβ1-3)n that is neither sulfated nor covalently linked to protein; referred to in older literature as hyaluronic acid.
- Hydrazinolysis
A chemical method that uses hydrazine to cleave amide bonds (e.g., the glycosylamine linkage between a sugar residue and asparagine or the acetamide bond in N-acetylhexosamines).
- I-type lectins
A class of lectins belonging to the immunoglobulin superfamily.
- Intrinsic glycan-binding proteins
Receptors that recognize glycans from the same organism. Typically they mediate cell–cell interactions or recognize extracellular molecules, but they can also recognize glycans on the same cell.
- Jelly-roll fold
Description of tertiary structure common to L-type lectins.
- Keratan sulfate
A polylactosamine [Galβ1-4GlcNAcβ1-3]n with sulfate esters at C-6 of N-acetylglucosamine and galactose residues, found as a side chain of a keratan sulfate proteoglycan.
- Ketal
An organic compound derived from a hemiketal by reaction with an alcohol. If the hemiketal is a sugar, the ketal is a glycoside.
- Ketose
A monosaccharide with a ketone group or a potential ketonic carbonyl group (typically at the C-2 position in natural compounds).
- L-type lectins
Superfamily of glycan-binding proteins with a common feature of tertiary structure called a “jelly-roll” fold.
- Lactose
The disaccharide Galβ1-4Glc; an abundant milk sugar.
- Lectin
A protein (other than an anticarbohydrate antibody) that specifically recognizes and binds to glycans without catalyzing a modification of the glycan.
- Lewis blood group antigens (e.g., Lex, Ley, and Lea)
A related set of glycans that carry α1-3/1-4 fucose residues covalently linked to galactose or N-acetylglucosamine.
- Ligand
A molecule that is recognized by a specific receptor. In the case of lectins, the ligands are partly or completely glycan-based and are sometimes called counterreceptors.
- Link module
A protein fold that interacts specifically with hyaluronan.
- Linkage analysis
A technology employing a combination of derivatization of hydroxyl groups, gas chromatography (GC) separation, and mass spectrometry to identify linkage sites in carbohydrate residues.
- Lipid A (also known as endotoxin)
Lipid that contains fatty acids linked to glucosamine with a variable number of phosphate groups and 1–4 units of ketodeoxyoctulosonic acid (Kdo). See Lipopolysaccharide.
- Lipid-linked oligosaccharide (LLO)
An oligosaccharide linked to dolichol.
- Lipid rafts
Small lateral microdomains of self-associating membrane molecules.
- Lipooligosaccharide (LOS)
Similar to lipopolysaccharide but lacking the O-antigen polysaccharide side chain repeats.
- Lipopolysaccharide (LPS)
A bacterial glycolipid composed of a polysaccharide (O-antigen), connected via a core oligosaccharide to lipid A that makes up the major portion of the outer leaflet of the outer membrane of Gram-negative bacteria. A major determinant of antigenic specificity, also known as heat-stable toxin or endotoxin.
- Lysosomal storage disorders
Human genetic disorders in which defects in lysosomal enzymes result in the accumulation of various glycans in the lysosomes (e.g., Tay–Sachs disease).
- Lysozyme
An endo-β-N-acetylhexosaminidase that cleaves the polysaccharide backbone of bacterial peptidoglycan.
- Mannan
Mannose-rich polysaccharide found in certain bacteria, fungi, and plants.
- Mannose 6-phosphate receptors
See P-type lectins.
- Mass spectrometry (MS)
An analysis technique providing masses of ionizable glycans and their fragments in the gas phase. The small sample requirements make it particularly useful.
- Matrix-assisted laser desorption/ionization (MALDI)
A procedure commonly used to produce charged species for mass spectrometric analysis.
- Membrane derived oligosaccharides (MDOs)
Highly charged β-glucans that create an osmotic buffer in the periplasmic space of Gram-negative bacteria.
- Metabolic labeling
A procedure dependent on metabolic processes in cells to incorporate isotopic or derivatized monosaccharides (or other moieties) into glycans for subsequent analysis.
- Methylation analysis
A method for carbohydrate structure analysis based on the acid stability of methyl ethers and the acid lability of glycosidic linkages; used to determine the linkage positions of monosaccharide residues in an oligosaccharide chain.
- Michael addition
The chemical reaction in which a nucleophile attacks the beta carbon of an α,b-unsaturated carbonyl compound. The reaction is used after O-glycan beta elimination in order attach probes to those sites.
- Microarray
A collection of molecules (e.g., DNA, proteins, or glycans) spatially addressed on a surface with micrometer dimensions.
- Microheterogeneity
Structural variations in the glycan at any given glycosylation site on a protein (one source of glycoforms).
- Molecular mimicry
Strategy some microbial pathogens use to evade immune reactions by decorating themselves with glycans similar to that of their hosts.
- Molecular dynamics (MD)
A computational technique based on Newton's laws of motion useful in simulating motions and structures of glycans or glycan–protein complexes.
- Molecular docking
A computational technique useful in predicting binding sites and geometry for glycan–protein complexes.
- Monosaccharide
Carbohydrate that cannot be hydrolyzed into a simpler carbohydrate. The building block of oligosaccharides and polysaccharides. Simple monosaccharides are polyhydroxyaldehydes or polyhydroxyketones with three or more carbon atoms.
- Mucin
Large glycoprotein with a high content of serine, threonine, and proline residues and numerous O-GalNAc-linked saccharides, often occurring in clusters on the polypeptide.
- Mucopolysaccharide
An out-of-date term replaced by the term, glycosaminoglycan. Still used as a group name for human disorders (“mucopolysaccharidoses”) involving glycosaminoglycan accumulation due to genetic deficiency of certain lysosomal enzymes.
- Mutarotation
The interconversion of stereoisomers at the anomeric center of a monosaccharide.
- Multivalent
Having multiple points of interaction. Often seen in oligomeric lectins in which low affinity individual interactions combine to provide high avidity.
- N-acetyllactosamine
A disaccharide with the sequence Galβ1-4GlcNAc.
- N-glycan (N-linked oligosaccharide, N-linked glycan)
Glycan covalently linked to the side-chain amide of asparagine residue of a polypeptide chain in the consensus sequence: -Asn-X-Ser/Thr. Unless otherwise stated, the term N-glycan is used generically in this book to denote the most common linkage region, Manβ1-4GlcNAcβ1-4GlcNAcβ1-N-Asn.
- Native chemical ligation
(NCL) A technique used to generate large polypeptides by condensation of smaller peptide fragments.
- Neuraminidase
See Sialidase.
- Nod factor
Lipooligosaccharide produced by Rhizobium bacteria that stimulates nodule formation and initiates nitrogen fixation in leguminous plants.
- Nonreducing terminus (nonreducing end)
Outermost end of an oligosaccharide or polysaccharide chain, opposite to that of the reducing end.
- Notch
Family of cell-surface receptors that are glycosylated on EGF-like repeats. Ligands include Delta and Serrate/Jagged.
- Nuclear magnetic resonance (NMR)
A spectroscopic technique based on detecting precession of magnetically active nuclei in strong magnetic fields. Useful in structure determination of both glycans and protein–glycan complexes as they exist in solution.
- Nuclear Overhauser effect (NOE)
An effect on intensities of resonances in NMR spectra that is often related to inter- nuclear distances in the case of proton–proton experiments.
- Nucleotide sugars
Activated forms of monosaccharides, such as UDP-Gal, GDP-Fuc, and CMP-Sia, typically used as donor substrates by glycosyltransferases.
- Nucleotide sugar transporters
Membrane-bound proteins that specifically transport nucleotide sugars from the cytosol into the lumen of intracellular organelles (e.g., the Golgi).
- O-GalNAc glycan
See O-glycan.
- O-GlcNAcylation
Dynamic modification of proteins by β-linked N-acetylglucosamine (a posttranslational modification similar to protein phosphorylation).
- O-glycan (O-linked oligosaccharide, O-linked glycan)
A glycan glycosidically linked to the hydroxyl group of the amino acids serine, threonine, tyrosine, or hydroxylysine. Unless otherwise stated, the term O-glycan is used in this book to denote the common linkage GalNAcα1-O-Ser/Thr.
- Oligosaccharide
Linear or branched chain of monosaccharides attached to one another via glycosidic linkages. The number of monosaccharide units can vary; the term polysaccharide is usually reserved for large glycans with repeating units.
- Peptidoglycan
A bacterial polysaccharide consisting of MurNAcβ1-4GlcNAcβ1-4 repeat units, covalently cross-linked to short peptides. Also known as murein, peptidoglycan represents the major structural component of the periplasm.
- Periodate oxidation
A reaction using periodate to cleave C–C bonds with vicinal hydroxyl groups (e.g., within carbohydrates) to form the two corresponding aldehydes.
- Pili (Fimbriae)
Hair-like appendages on the surface of some bacteria that often contain adhesins.
- Polyisoprenoid
A lipid polymer composed of repeating units of the unsaturated 5-carbon isoprene unit. See Dolichol and Undecaprenol.
- Poly-N-acetyllactosamine
Repeating units of N-acetyllactosamines [Galβ1-4GlcNAcβ1-3]n, of variable length (sometimes called PolyLacNAc).
- Polymerase chain reaction (PCR)
The process used to amplify DNA starting from a template DNA strand and complementary oligonucleotide primers.
- Polysaccharide
Glycan composed of repeating monosaccharides, generally greater than ten monosaccharide units in length.
- Polysialic acid
A homopolymer of sialic acids abundant in the brain and fish eggs and found on certain pathogenic bacteria.
- Protecting group
A chemical moiety commonly used in glycan synthesis that masks hydroxyl groups in order to prevent them from reacting with other chemical reagents.
- Protein data bank (PDB)
A repository containing atomic coordinates primarily for proteins, but also nucleic acids and protein-carbohydrate complexes. Each entry is given a four-element alpha-numeric code.
- Proteoglycan
Any protein with one or more covalently attached glycosaminoglycan chains.
- Proteome
The total collection of proteins in a cell, tissue, or organism, under specific conditions of time, space, and environment.
- P-type lectins
Class of lectins that recognize mannose-6-phosphate (also called M6P receptors).
- Pulsed amperometric detection
A detection procedure based on conduction at high pH and used in HPLC analysis of monosaccharide composition.
- Pyranose
Six-membered (five carbons and one oxygen, i.e., an oxygen heterocycle) ring form of a monosaccharide; the most common form found for hexoses and pentoses. The name is based on the structural similarity to the compound “pyran.”
- R-type lectins
Superfamily of glycan-binding proteins that contain a carbohydrate-recognition domain similar to that in ricin.
- Receptor
A protein that binds to a ligand and initiates signal transmission or other cellular activity. In this book, most receptors are lectins (i.e., they recognize glycans). In microbiology, the terminology is reversed: Adhesins or agglutinins on the microbes bind to receptors which are glycans on the host cell.
- Reducing terminus (reducing end)
End of a glycan that has reducing power because it is unattached to an aglycone and is thus a hemiacetal. In a glycoconjugate, reducing terminus is also used as a synonym for a potential reducing terminus, referring to the end of a glycan covalently attached to the aglycone by a glycosidic bond (i.e., it would have reducing power if it were released).
- Regiochemistry
The region among many possible regions of a molecule that is involved in a chemical reaction. For glycosidic linkages, regiochemistry denotes the hydroxyl group of one monosaccharide that is bound to the anomeric position of the other (i.e., 1-3 vs. 1-4 linkage).
- S-layer (surface-layer)
A protein monolayer coating often containing covalently linked glycans and found in the cell envelope of many bacteria and archea.
- Saccharide
A generic term for any carbohydrate or assembly of carbohydrates, in free form or attached to another molecule, used interchangeably in this book with carbohydrate and glycan.
- Saccharolipid
A glycoconjugate comprising fatty acyl chains covalently attached directly to a sugar backbone (e.g., Lipid A).
- Saturation transfer difference (STD)
An NMR technique useful in identifying parts of glycans in close approach to protons in the binding sites of protein receptors.
- Selectin
A C-type (Ca++-dependent) lectin expressed by cells in the vasculature and bloodstream. The three known selectins are L-selectin/CD62L (expressed by most leukocytes), E-selectin/CD62E (expressed by cytokine-activated endothelial cells), and P-selectin/CD62P (expressed by activated endothelial cells and platelets).
- Ser/Thr-linked oligosaccharide
See O-glycan.
- Sialic acids
Family of acidic sugars with a nine-carbon backbone, of which the most common is N-acetylneuraminic acid, in vertebrates.
- Sialidase
Enzyme that releases sialic acid residues from a glycoconjugate. Older name was neuraminidase, now used only refer to the influenza sialidase.
- Sialome
Total array of sialic acid types and linkages expressed by a particular cell tissue or organism, under specified conditions of time, space and environment.
- Siglecs
Sialic acid–binding proteins that are members of the I-type lectin family and have an amino-terminal V-set domain with typical conserved residues.
- Small-angle X-ray scattering (SAXS)
An X-ray scattering technique useful in defining the shape of large molecular complexes as they exist in solution.
- Sphingolipids
Lipids with ceramide as their core structure.
- Sphingosine
Long-chain amino alcohol (forms ceramide when in amide linkage with a fatty acid).
- Sugar
A generic term often used to refer to any carbohydrate, but most frequently to low-molecular-weight carbohydrates that are sweet in taste. Table sugar, sucrose, is a nonreducing disaccharide (Fruβ2-1αGlc). Oligosaccharides are sometimes called “sugar chains” and individual monosaccharides in a sugar chain are sometimes referred to as “sugar residues.”
- Surface plasmon resonance (SPR)
An optical technique for the measurement of adsorption of materials onto a surface. Frequently used to estimate affinities of proteins for glycans on coated chips.
- Teichoic acid
A complex polymer consisting of either phosphoglycerol- or phosphoribitol-carrying carbohydrates or amino acids, found on the surface of Gram-positive bacteria.
- Time of flight (TOF)
An analysis technique used in mass spectrometry to separate species of different mass based on velocity differences for particles with equal kinetic energy.
- Transfer nuclear Overhauser effect (trNOE)
An NMR technique particularly useful in determining the conformation of glycans noncovalently bound to proteins.
- Thrombospondin repeats (TSR)
Small protein motifs (50–60 amino acids) with six conserved cysteine residues that form three disulfide bonds. Serve as sites for glycan modification.
- Transcriptome
The total collection of RNA transcripts in a cell, tissue, or organism, under specific conditions of time, space, and environment.
- Undecaprenol (bactoprenol, C55 isoprenoid)
A polyisoprenoid lipid carrier for membrane-bound glycan synthesis in bacteria.
- X-ray crystallography
A structure determination technique dependent on scattering of X-rays from molecules ordered in crystals. Useful in the determination of three-dimensional structures of protein–glycan complexes.
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