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 a-D-glucopyranose and b-Dglucopyranose, drawn as both Haworth projections and ball-andstick models
Conformations of the cyclohexane ring (a) in the boat conformation
and (b) in the chair conformation
4C
1
more stable
1C
4
less stable
The two idealized chair conformations of b-D-glucopyranose
Oxidized Monosaccharide Derivatives
aldonic acid
uronic acid
D-Glucono-d-lactone and D-glucurono-d-lactone are, respectively,
the lactones of D-gluconic acid and D-glucuronic acid.
lactones
The reversible oxidation of L-ascorbic acid to L-dehydroascorbic acid
an a-ketoacid
N-Acetyl-neuraminic (sialic) acid in its linear and pyranose forms
The acid-catalyzed condensation of a-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: b-lactose
Common disaccharide: b-maltose
Common disaccharide: a-isomaltose
Common disaccharide: b-cellobiose
Electron micrograph of the cellulose fibers in the cell wall of the
alga, Chaetomorpha melagonium
Primary structure of cellulose:
......b-D-glucopyranosyl-(1,4)-b-D-glucopyranosyl-......
Extensive
H-bonding
network (intraand interchain:
responsible for
the rigidity of
cellulose fibers
Proposed structural model of cellulose
O
O
Primary structure of chitin:
......b-D-GlcNAc-(1,4)-b-D-GlcNAc-......
A structural motif similar to that of cellulose:
thus, similar physical properties (structure-function correlations)
a-Amylose: D-glucose residues are linked by
a-(1  4) bonds (red)
......a-D-glucopyranosyl-(1,4)-a-D-glucopyranosyl-......
a-Amylose: this regularly repeating polymer
forms a left-handed helix.
Amylopectin: Primary structure near one of it’s
a-(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-b-Dglucosamine–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
Hyaluronidase:
a glycosidase that
cleaves the b-(1,4)
linkages of
hyaluronic acid
X-ray fiber structure of Ca2+ hyaluronate
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) grampositive bacteria and (b) gram-negative bacteria
Chemical structure of peptidoglycan of bacteria:
the repeating unit of peptidoglycan
Note the pentaglycine
cross-linkages between
the chains
Lysozyme: a glycosidase
that cleaves the b-(1,4)
linkages of peptidoglycans
Chemical structure of peptidoglycan: the S.
aureus bacterial cell wall peptidoglycan
Structure of penicillin: inhibits
bacterial cell wall biosynthesis
Enzymatic inactivation of penicillin
Other bacterial cell wall
antigenic groups
Structure of teichoic acid
Unusual monosaccharides occur in the O-antigens of gramnegative 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