Unformatted text preview: CHEM 350: Introduction to Biological Chemistry
Brian Lee, Ph.D.
Ofﬁce: Neckers 146G or 324
Ho urs: 9:30am to 10:30am or by appointment
Textbook (required, U.S. edition only)
Fundamentals of Biochemistry, 3rd Ed., Voet, Voet & Pratt.
Study Guide (recommended)
Student Companion to Fundamentals of Biochemistry, 3rd Ed.
Tuesday 6:30 to 7:30 pm in Neckers 218
Thursday 5:00 to 6:00 pm in Neckers 410 Announcements
Undergraduate Research Opportunities
Research for credit (such as CHEM 396 or CHEM 496)
Student worker ($8.00 per hour) (http://www.siu.edu/~fao/jobs/)
Undergraduate Assistantships (http://www.siu.edu/~fao/jobs/)
McNair Scholars Program (http://www.siu.edu/~mcnair)
REACH Awards Competition (http://www.siu.edu/~reach/)
Summer Research Experiences for Undergraduates (REU)
Deadline for SIUC REU Program is March 7th
For other REU programs, search the National Science Foundation site:
Students must contact the individual sites for information and
application materials. NSF does not have application materials and does
not select student participants. A contact person and contact
information is listed for each site. Assignments
Read Chapter 9 Lipids and Biological Membranes
Chapter 9 Problems
Student Companion site for Voet, Voet & Pratt
http://bcs.wiley.com/he-bcs/Books?action=index&bcsId=4274&itemId=0470129301 Second Midterm Exam, Wednesday February 29th
Chapters 6 through 9 (All exams are cumulative)
No class on Monday, February 27th (no ofﬁce hours) Help Desk
Tuesday 6:30 to 7:30 pm in Neckers 218
Thursday 5:00 to 6:00 pm in Neckers 410 The free anomeric carbon is also a mild reducing agent.
Saccharides with a free anomeric carbon that has not
formed a glycoside are called reducing sugars.
Reactions with Cu2+ solution (Fehling’s solution) or
Ag+ (Tollens’ reagent) are used to detect reducing sugars. -D-glucose D-glucose D-gluconate The ano meric carbon is oxidized to a carboxylic acid group. The anomeric carbon is more reactive than other sugar carbons
Reactions with alcohols and amines form adducts through
note the sufﬁx “-side”
Nucleosides are also adducts between sugar and base
Reaction with methanol Oligosaccharides
Sugars linked by O-glycosidic
bonds deﬁned by the carbon
Sucrose is a 1->2 linkage
between both anomeric carbons
of glucose and fructose, thus
sucrose is a non-reducing sugar. Polysaccharides for energy storage:
Glycogen - (animals)
-1,4 glucose chains
with -1,6 branches
at every 10 units
Starch - (plants)
Amylose - -1,4 glucose chains
Amylopectin - -1,4 glucose chains
with -1,6 branches at every 30 units glycogen The most stable structure for
starch and glycogen is a coiled
helix stabilized by inter-chain
hydrogen bonds with six residues
per turn. Amylopectin and Glycogen
are both branched with a
Branched structures are
more compact than linear
forms, allowing more
efﬁcient energy storage. The most abundant organic molecule is cellulose,
Structural component of plant cell walls,
ß1->4 linkages produce straight chains of cellulose;
Ideal for constructing ﬁbers and indigestible by mammals. cellulose ﬁbers in algae Chitin (arthropod exoskeletons).
N-acetylglucosamine residues in
Same as cellulose, except for the
C2-N-acetyl group June bug Heteropolysaccharide: Agarose - component of red algae cell walls.
Agarose gels - heated agarose solutions form a gel upon cooling.
Double helical structures trap water molecules. Ideal for
electrophoretic separations of nucleic acid (DNA) molecules. Bacterial cell walls: Peptidoglycan
This is the target of lysozyme.
cross-linked by short peptides. Glycosaminoglycans - gel-like, in extracellular matrix.
Often disaccharide repeats. O- and N-sulfate & N-acetyl.
Slimy and mucous-like due to high viscosity and elasticity.
Chondroitin 4-sulfate & keratin sulfate cartilage & connective tissue. D-Glucuronate N-Acetyl-Dgalactosamine4-sulfate D-Galactose N-Acetyl-Dglucosamine6-sulfate Glycosaminoglycans - gel-like, in extracellular matrix.
Hyaluronate - synovial ﬂuid
in joints and vitreous humor
in eye D-Glucuronate + Heparin - most negatively
associated with arterial
walls, released during injury,
prevents excess clotting. N-Acetyl-D-glucosamine D-Glucuronate-2-sulfate
or L-Iduronate-2-sulfate N-SulfoD-glucosamine6-sulfate Proteoglycan structure: Cell surface or extracellular matrix. Glycosaminoglycan chains are
joined covalently to a membrane protein or a secreted protein. Proteoglycan aggregates: Supramolecular assemblies of aggrecan core proteins bound to a
single molecule of hyaluronate (Example, proteoglycan aggregate of
the extracellular matrix). Keratan sulfate and
chondroitin sulfate are
linked to Ser residues
of aggrecan core to form
brush-like structures. Glycoproteins - most eukaryotic proteins are covalently associated with
a carbohydrate Proteoglycan - linked to glycosaminoglycans, found in cartilege
and connective tissue Peptidoglycan - network of covalently linked polysaccharides and
polypeptide, encase bacterial cells Other glycoproteins - are found in the cytosol, associated with the cell
membrane and in extracellular spaces. Sugars can be N-linked through asparagine or O-linked through serine
or threonine residues. Glycoproteins: proteins covalently linked to oligosaccharides.
They have speciﬁc sites for recognition and high-afﬁnity binding by
other proteins “Sequence” of glycosylation is
highly speciﬁc to species and
tissue, which permits speciﬁc
recognition of cell types. Glycoforms vary the content and sequence of sugars attached
to a particular protein. Glycosylation can be branched
into brush-like structures that
are speciﬁcally recognized by
cell surface receptors. Table 8-1 Glycosylation begins in
the ER and terminal
place in the Golgi
in vesicles with
targeting to the
or internal vesicles
such as the lysosome.
Lysosome contains digestive enzyme that degrade and recycle
cellular components as well as digest extracellular material Glycolipids: lipids with
lipopolysaccharides Lectins are proteins that
bind to speciﬁc
Lectins participate in
cell-cell contacts Hemagglutinin
virus binds to sialic acid sugars
to gain entry into human cells.
Sialic acid recognition ...
View Full Document