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Unformatted text preview: CHEM 350: Introduction to Biological Chemistry
Brian Lee, Ph.D.
Ofﬁce: Neckers 146G or 324
Hours: 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/) (due Jan 30th)
Undergraduate Scholarships (due Jan 31st)
Chemistry Majors see Department website
Science Majors see College of Science website
Summer Research Experiences for Undergraduates (REU)
Read Chapter 5 Proteins
Chapter 5 Problems
• First Midterm Exam, Monday February 6th
– Chapters 1 through 5 • Help Desk
Tuesday 6:30-7:30pm in Neckers 218
Thursday 5:00-6:00pm in Neckers 410 Peptides also have a
curve and pI. Naming Peptides
AEGK Determine the pI 9.87 1
pI = ( pK 2 + pK 3 )
= (4.07 + 9.87) = 6.97
2 4.07 pI 2.16 pKa
+ 10.54 high
-2 Amino acids with Ionizable Side-Chains (R-groups) 3.90 10.46 4.07 10.54 12.48
6.04 8.37 Stereochemistry
Chiral molecules are
optically active, meaning
they rotate plane
polarized light Figure 4-9 chiral center – assymetric center Chirality (Stereochemistry) -mirror image is not superimposible
-tetrahedral carbon has four different substituents
-mirror image molecules are enantiomers
-optical isomers rotate plane polarised light
-L (-) for levorotary -D (+) for dextrorotary Fischer Convention for Conﬁguration
All 20 common -amino acids are L stereoisomers Cahn Ingold Prelog rules (RS)
-assign priority by atomic number
-lowest priority points away
-rotation from highest priority
-left handed (CCW) is S
-right handed (CW) is R All amino acids are L
All amino acids but one are S
Only Cysteine has R chirality
Due to Sulfur being higher
in priority than Carbon L and S Why is stereochemistry important?
Biological systems are stereospeciﬁc.
Ibuprofen – only one enantiomer is anti-inﬂammatory
Thalidomide – one enantiomer is a mild sedative,
the other enantiomer causes birth defects.
Thalidomide was often prescribed for morning sickness Modiﬁed Amino Acids
Hydroxyproline is found in
collagen (gelatin) and plant
cell walls. Proline permits
formation of the collagen
triple helix (ch 6).
Hydroxylysine is also found in
collagen and is used to create
covalent cross-links between
collagen chains. g-Carboxyglutamate is
found in prothrombin.
The added carboxylate
allows this amino acid
to chelate calcium ions. “21st amino acid”
UGA stop codon
serine on tRNAsec
is modiﬁed prior
to translation. Amino acids found in metabolism. Ornithine is a catalytic
intermediate of the urea cycle. Citrulline is generated
from ornithine. Neither is incorporated in proteins during
translation of mRNA by the ribosome. Citrulline can be generated by deamination of Arginine. collagen signal transduction actin Figure 4-14 thrombin histone neurotransmitter allergic response thyroid hormone
Figure 4-15 neurotransmitter Glutathione (GSH) is a
tripeptide of Glu-Cys-Gly.
Note: Glu is linked by
GSH protects cells
from reactive oxygen
species which can
cause oxidative damage
to DNA and proteins Green Fluorescent Protein
Nobel Prize in 2008
Roger Tsien Modiﬁed Tyrosine
Absorbs UV light and
emits green light. ...
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