GLYCOSIDIC LINKAGE Flashcards by decerie faller

Disaccharides (C12H22O11)

•maltose
•sucrose
•cellobiose

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C12H22O11 + H2O ➡️ C6H12O6

✅ white, crystalline, sweet solids

➡️ sucrose- very soluble in water
➡️ maltose- fairly soluble
➡️ lactose- slightly soluble
➡️ optically active
➡️ too largely to pass the cell membrane

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DISACCHARIDES:
• maltose

➡️ a cleavage product of starch (e.g., amylose), is a disaccharide with an a(1-4) glycosidic link between C1-C4 OH of 2 glucose. It is the a anomer (C1 0 points down)

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Celloboise

➡️ a product of cellulose breakdown, is the other wise equivalent B anomer (O on C1 points up). The B(1-4) glycosidic linkage is represented as a zig-zag but one glucose is actually flipped over relative to the other.

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Maltase

➡️ hydrolyzes alpha glycosidic linkage

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disaccharides: sucrose and lactose

➡️sucrose (table sugar) has a _______ bond
➡️lactose (milk sugar) is composed of _____ & _____

➡️sucrose (table sugar) has a glycosidic bond linking the anomeric hydroxyls of glucose & fructose.

➡️lactose (milk sugar) is composed of galactose & glucose.

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The configuration at the anomeric C of glucose is a (O points down from ring), the linkage is a(1-2)

The full name of sucrose is _______________

a-D-glucopyranosyl1-(1-2)-B-D-fructopyranose.

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Lactose is with B(1-4) linkage from the anomeric OH of galactose. It’s full name is ________________

B-D-galactopyranosyl1-(1-4)-a-D-glycopyranose

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Polysaccharides:

•plants store glucose as amylose or amylopectin, glucose polymers collectively called starch

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Glucose storage in ________ form minimizes osmotic effects.

polymeric

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________ is a glucose polymer with a(1-4) linkages.

Amylose

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The end of the polysaccharide with an anomeric C1 not involved in a glycosidic bond is called the________ ___.

reducing end

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Amylopectin

•is a glucose polymer with mainly a(1-4) linkages, but it also has branched formed by a (1-6) linkages.

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The branched produce a compact structure & provide multiple chain ends at which ______ ______ can occur.

enzymatic cleavage

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Glycogen

•the glucose storage polymer in animals, is similar in structure to amylopectin.

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glycogen has more a(1-6) ________

branches

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The highly branched structure permits ______ ______ release from glycogen stores, e.g., in muscle during exercise.

rapid glucose

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The ability to rapidly mobilize glucose is more essential to _______ than to plants.

animals

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Cellulose

•a major constituents of plant cell walls, consists of long linear chains of glucose with B(1-4) linkages.

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Every other glucose is flipped over, due to ______________

due to B linkages.

this promotes intro-chain and inter-chain H-bonds and can der Waals interactions, that cause cellulose chains to be straight & rigid, and pack with a crystalline arrangement in thigh bundles- microfibrils

see: botany online website; website at Georgia tech

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Multi subunit Cellulose Synthase___________

complexes in the plasma membrane spin out from the cell surface microfibrils consisting of 36 parallel, interacting cellulose chains.

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These microfibrils are ____ ______.

very strong

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The role of cellulose is to ____________

impart strength and rigidity to plant cell walls, which can withstand high hydrostatic pressure gradients.

Osmotic swelling is prevented.

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Glycosaminoglycans (mucopolysaccharodes)

are linear polymers of repeating disaccharides.

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The constituent monosaccharides tench yo be modified, with _____ groups, _____ groups, ______ _____ ad _____ groups etc.

with acidic group, amino groups, sulfate hydroxyl and amino groups etc.

Glycosaminoglycans tend to be _______ charged, because of the prevalence of acidic groups.

Negatively charged

HTA Lito ate (hyalouronan) is a _________ with a repeating disaccharide consisting of 2 glucose derivatives, glucuronate (glucuronic acid) & N-acetyl-glucosamine.

Glycosaminoglycan

The glycosidic linkage are ______ & _____

B(1-3) & B(1-4)

Proteoglycans are _______ that are covalently linked to sirens residues of specific ______ ______.

glycosaminoglycans ; core proteins.

The glycosaminoglycan chain is synthesized by _____ addition of sugar residues due to the core protein.

sequential

Some proteoglycans of the extracellular matrix ____ non-covalently to ______ via protein domains called _____ ____

bind; hyaluronate; link molecules.

Multiple copies of _____ proteoglycan associate with hyaluronate in cartilage to form large complexes .

aggrecan

Versican

another proteoglycan, binds hyaluronate in the extrallular matrix of loose connective tissues.

Heparan sulfate

•is initially synthesized on a membrane-embedded core protein as a polymer of altering N-acetylglucosamine and glucuronate residues.

In segments of the polymer, glucuronate residues may be converted to the sulfates sugar _____ acid

iduronic acid

N-acetylglucossmine residues may be ______ And/or _____.

deacetylated and/or sulfated.

Heparin

•a soluble glycosaminoglycan found in granules of mast cells, has a structure similar to that of heparan sulfates, but is more highly sulfated

Heparin inhibits clot formation when released into the blood, by interacting with the _______ _______.

Protein antithrombin

Heparin has an ______ ______ ______.

extended helical conformation.

Charge repulsion

by the many negatively charged groups may contribute to this confirmations

Some cell surfaces hepari sulfate

glycosaminoglycans remain covalently linked to core proteins embedded in the plasma membrane.

The core protein of a _______ heparan sulfate proteoglycan as a a single ______________, as in simplified diagram

syndecan; transmembrane a-helix

The core protein of _____ heparan sulfate proteoglycan is attached to the outer surface of the plasma membrane via covalent _______ modified phosphatidylinositol _____

glypican; linkage to: lipid

Proteins involved in ____ & ____ at the cell surface recognize & bend heparan sulfate chains.

Signaling & adhesion

Binding of some _____ factors (small proteins) to cell surface receptors is enhanced by their binding alto to heparan sulfates.

growth

Regulated cell surface ____ enzymes may remove _____ groups at particular locations on heparan sulfate chains to ____ affinity for signal proteins, e.g., growth factors

Sulf; sulfate; alter

Oligosaccharides

are covalently attached to proteins or to membrane lipids may be linear or branched chains.

O-linked Oligosaccharide

chains of glycoproteins vary in complexity. They link to a protein via a glycosidic bond between a sugar residue & a serine or threonine OH

O-linked oligosaccharides have roles in _______, _______, and _______ ________.

recognition, interaction, and enzyme regulation.

N-acetylglucosamine (GlcNAc)

•a common O-linked glycosylation of protein serine or threonine residues. •many cellular proteins, including enzymes & transcription factors are regulated by reversible GlcNAc attachment. •often attachment of GlcNAc to a protein OH alternates with phosphorylation, with these 2 modifications having opposite regulatory effects (stimulation or inhibition)

N-linked oligosaccharides of glycoproteins tend to be ______ and _____

complex and branched.

First N-acetylglucosamine is linked to a protein via the __________ of an asparagine residue in a particular 3-amino acid sequence

side-chain N

N-linked oligosaccharides key: NAN = Gal= NAG= Man= Fuc=

NAN= N-acetylneuraminate Gal= galactose NAG= N-acetylglucosamine Man= mannose Fuc= fucose

N-linked oligosaccharides key: NAN = Gal= NAG= Man= Fuc=

NAN= N-acetylneuraminate Gal= galactose NAG= N-acetylglucosamine Man= mannose Fuc= fucose

N-linked oligosaccharides key: NAN = Gal= NAG= Man= Fuc=

NAN= N-acetylneuraminate Gal= galactose NAG= N-acetylglucosamine Man= mannose Fuc= fucose

N-linked oligosaccharides key: NAN = Gal= NAG= Man= Fuc=

NAN= N-acetylneuraminate Gal= galactose NAG= N-acetylglucosamine Man= mannose Fuc= fucose

the N-linked oligosaccharides chain is modified by ______ and _____ of residues, to yield a characteristic branched structure.

removal and addition

many proteins _______ by cells have attached N-linked oligosaccharide chain

secreted

________ disease have been attributed to deficiency of particular enzymes involved in synthesizing or modifying oligosaccharide chain of these glycoproteins.

Genetic disease

such disease, and ____ _____ studies in mice, have been used to define pathways of modification of oligosaccharide chains of glycoproteins and glycolipids.

gene knockout

_______ chains of plasma membrane glycoproteins and glycolipids usually face the ______ of the cell.

Carbohydrate chain ; outside of the cell

_______ chains of plasma membrane glycoproteins and glycolipids usually face the ______ of the cell.

Carbohydrate chain ; outside of the cell

they have roles in cell-cell _______ and _____, and in forming a protective layer on the surface of some cell.

interaction and signaling

Lectins

•are glycoproteins that recognizes and bind to specific oligosaccharides

Concanavalin A & wheat germ agglutinin

•are plant lectins that have been useful research tools.

the C-type lectin-like domains is a ________ binding carbohydrate recognition domain in many animal lectins.

Ca++

Recognition /binding of CHO

•moieties of glycoproteins, glycolipids & proteoglycans by animal lectins is a factor in: • cell-cell recognition •adhesion of cells to have the extracellular matrix • interaction of cells with chemo lines and growth factors. • recognition of disease-causing microorganisms • initiation and control of inflammation

Examples of animal lectins:

•Mannan-binding lectin (MBL) ➡️a glycoprotein found in blood plasma. It binds cell surface carbohydrates of disease-causing microorganisms & promotes phagocytosis of these organisms as part of the immune response.

Selectins

are integral proteins of mammalian cell plasma membranes with roles in cell-cell recognition & binding

the C-type lectin-like domain

is at the end of multi-domain extracellular segment extending out from the cell surface

cleavage site

just outside the transmembrane a-helix provides a mechanism for regulated release of some lectins from the cell surface

cytosolic domain

participates in regulated interaction with the actin cytoskeleton.