The stereochemical relationships, shown in Fischer projection, among the D-aldoses with three to six carbon atoms.

The stereochemical relationships among the D-ketoses with three to six carbon atoms.

The reactions of alcohols with (a) aldehydes to form hemiacetals and (b) ketones to form hemiketals. These reactions are freely reversible in aqueous solution.

Cyclization of hexoses: anomerization

The anomeric monosaccharides -D-glucopyranose and -D-glucopyranose, drawn as both Haworth projections and ball-and-

stick models

Conformations of the cyclohexane ring (a) in the boat conformation and (b) in the chair conformation

The two idealized chair conformations of -D-glucopyranose

4C11C4

more stable less stable

D-Glucono--lactone and D-glucurono--lactone are, respectively, the lactones of D-gluconic acid and D-glucuronic acid.

aldonic acid uronic acid

Oxidized Monosaccharide Derivatives

The reversible oxidation of L-ascorbic acid to L-dehydroascorbic acid

lactones

N-Acetyl-neuraminic (sialic) acid in its linear and pyranose forms

an -ketoacid

The acid-catalyzed condensation of -D-glucopyranose with methanol to form an anomeric pair of methyl D-glucopyranosides (Fischer glycosidation); furanosides also form under these conditions

Common disaccharide: sucrose

Common disaccharide: -lactose

Common disaccharide: -maltose

Common disaccharide: -isomaltose

Common disaccharide: -cellobiose

Electron micrograph of the cellulose fibers in the cell wall of the alga, Chaetomorpha melagonium

Primary structure of cellulose:......-D-glucopyranosyl-(1,4)--D-glucopyranosyl-......

Proposed structural model of cellulose

Extensive H-bonding

network (intra-and interchain:responsible for

the rigidity ofcellulose fibers

Primary structure of chitin: ......-D-GlcNAc-(1,4)--D-GlcNAc-......

A structural motif similar to that of cellulose:thus, similar physical properties (structure-function correlations)

O O

-Amylose: D-glucose residues are linked by -(1 4) bonds (red)

......-D-glucopyranosyl-(1,4)--D-glucopyranosyl-......

-Amylose: this regularly repeating polymer forms a left-handed helix.

Amylopectin: Primary structure near one of it’s (1 6) branch points (red)

Amylopectin showing its bushlike (compact, globular) structure (glucose residues at

branch points indicated in red)

Glycogen is amylopectin-like but with greater branching

Photomicrograph showing the glycogen granules (pink) in the cytoplasm of a liver cell

N-Linked oligosaccharides: all N-glycosidic protein attachments occur through a N-acetyl--D-glucosamine–Asn bond to Asn–X–Ser/Thr

N-Linked oligosaccharides: N-linked oligosaccharides usually have the branched (mannose)3(NAG)2 core shown

N-Linked oligosaccharides:

some examples of N-linked oligosaccharides

The microheterogeneous N-linked oligosaccharide of RNase B has the (mannose)5(NAG)2 core shown

Some common O-glycosidic attachments of oligosaccharides to glycoproteins (red): blood group antigens (glycophorin)

Disaccharide repeating units of the common glycosaminoglycans (proteoglycans):

connective tissue; cartilage

X-ray fiber structure of Ca2+ hyaluronate

Hyaluronidase:a glycosidase thatcleaves the -(1,4)

linkages ofhyaluronic acid

Proteoglycans: (a) Electron micrograph showing a central strand of hyaluronic acid. (b) Bottlebrush model of the proteoglycan aggrecan.

Model of oligosaccharide dynamics in bovine pancreatic ribonuclease B (RNase B)

Schematic diagram comparing the cell envelopes of (a) gram-positive bacteria and (b) gram-negative bacteria

Chemical structure of peptidoglycan of bacteria: the repeating unit of peptidoglycan

Chemical structure of peptidoglycan: the S. aureus bacterial cell wall peptidoglycan

Note the pentaglycinecross-linkages between

the chains

Lysozyme: a glycosidasethat cleaves the -(1,4)

linkages of peptidoglycans

Structure of penicillin: inhibits bacterial cell wall biosynthesis

Enzymatic inactivation of penicillin

Structure of teichoic acid

Other bacterial cell wallantigenic groups

Unusual monosaccharides occur in the O-antigens of gram-negative bacteria; are subject to rapid mutational

alteration (new bacterial strains)

END

The surfaces of a normal mouse cell as seen in the electron microscope.

The surfaces of a cancerous cell as seen in the electron microscope.

Scanning electron micrograph of tissue from the inside of a human cheek.

Properties of some proteoglycans