Subject: Do you like to win? How about free stuff?

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Subject Do you like to win? How about free
stuff? Well, you can do both if you submit the
winning chemistry club T-shirt design. Designs
may be submitted in the chemistry library in the
box near the microwave - you can't miss the big
black arrow showing you the way. Designs are due
the Friday of finals week (December 15, 2006) at
430 PM. Check out the attachments for a look at
last year's winning designs and a totally awesome
poster. Your friendly FUNdraising chem. club
coordinator, Tricia
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Nov 20 Liliya A. Yatsunyk Ph.D. Northwestern
University, "Synthesis, Structure, and Magnetic
Spectroscopies of Non-Planar Hemes as Models of
the Cytochromes b Heme Centers" 400 SL 130 Nov
21 Melinda Kangala, Graduate Student, Western
Washington University (Chemistry). Thesis
Defense. 300 p.m. BI 212 Nov 28 Danielle Dube
Ph.D. Stanford University "Chemical Tools to
Target and Understand Glycosylation" 400 p.m.
SL 130
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Wednesday 29th November, Dr. Vett Lloyd will be
presenting her seminar "Dolly the fly - why the
world needs cloned Drosophila." Dr. Lloyd is an
associate professor from Mount Allison
University, New Brunswick Canada. She studies
chromatin structure and gene regulation using
the fruit fly Drosophila as a model. She is
particularly interested in parent of origin
effects such as imprinting, and the particular
epigenetic (ie., chromatin-based) problems
encountered during the process of cloning
complex eukaryotes. She also has a pretty
awesome website (Drosophiloid.ca) which provides
summaries of her research, in addition to expert
tips for getting rid of flies in your home.
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Ch 14 Kinetics!
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New Kinetic Parameter
Kcat Vmax ET
when Kcat ltltS
Turnover Number
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Previously defined Vo k2ES and ES
ES KM
Vo kcatES/KM
When SltltKM. E?ET
Vo kcatETS/KM
Kcat/KM rate constant for interaction of E and
S (turnover number) Can be used to measure an
enzymes preference for different substrates.
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What do these values tell you?
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Determining kcat and KM from intial rate data
o
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Vmax 150-160?? Km ???
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Vmax 150-160?? Km ???
Lineweaver- Burk plot
Vmax 164 mM/min Km 32.2 mM
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Figure 14-9 A double reciprocal (LineweaverBurk)
plot.
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Table 14-1 Values of KM, kcat, and kcat/KM for
Some Enzymes and Substrates.
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How does the substrate contact the enzyme?
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Figure 14-10 Cross section through the active
site of human superoxide dismutase (SOD).
Cu2 and R 143 form the binding site for O2-.
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Inhibiting Enzyme Activity
Reversible Irreversible Competetive Uncompetetiv
e Mixed
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Stryer Fig. 8.15 Types of inhibition
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Stryer Fig. 8.16 Methotrexate inhibits the
formation of THF from DHF by binding very
tightly to the enzyme Dihydrofolate reductase.
DHFR is required for regenerating THF, which is
required for TMP synthesis.
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Another important competitive inhibitor helped
Sir Hans Krebs elucidate the TCA cycle Malonate
Succinate DH
CO2--CH2-CH2-CO2-
?
CO2--CHCH-CO2-
FAD
FADH2
Succinate
What type of rxn is this? Whats missing?

Name S and then name E.
Inhibitor is malonate CO2--CH2-CO2-
WHY?
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Figure 14-11 Competitive inhibition.
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Stryer Fig. 8.17 Competitive Inhibition
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Figure 14-12 LineweaverBurk plot of the
competitively inhibited MichaelisMenten enzyme
described by Fig. 14-11.
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competitive inhibition
KM increases Vmax unchanged
inhibitor
1/Vo
Vmax
no inhibitor
100
Vo
75
50
inhibitor
no inhibitor
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0
S
1/S
0
10
20
30
KM
-1/KM
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Stryer Fig. 8.18 Non-competitive Inhibition
EDTA
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Uncompetetive I interacts with ES
Mixed I interacts with either E or ES (or both)
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Table 14-2 Effects of Inhibitors on the
Parameters of the MichaelisMenten Equationa
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Summary of simple inhibition models
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Figure 14-14 LineweaverBurk plot of a simple
Michaelis-Menten enzyme in the presence of a
mixed inhibitor.
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Irreversible Inhibition
V vs. S looks like noncompetitive inhibition.
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Stryer Fig. 8.20
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Stryer Fig. 8.19
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Stryer Fig. 8.21
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Proline racemase (bacterial)
Stryer 8.24 Transition state analogs are potent
inhibitors.
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Suicide Inhibitor
Stryer Fig. 8.23 Inhibition of monoamine
oxidase, an enzyme involved in inactivating
neurotransmitters such as dopamine.
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Two substrate reactions
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What would you name this enzyme? (In this case
it is named for the reverse rxn). So 1. name
the product.
2. What category of enzyme is this?
LDH
Absorbs light at 340 nm
Ordered Sequential Displacement All substrates
bind E before any P is produced in a specific
order.
Stryer p. 207
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An ordered Bi-Bi reaction
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Random Sequential Displacement order not
specified.
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Figure 14-17 Some bisubstrate reactions. (a) The
peptide hydrolysis reaction catalyzed by trypsin.
(b) The alcohol dehydrogenase reaction.
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Figure 14-13 LineweaverBurk plot of a simple
MichaelisMenten enzyme in the presence of
uncompetitive inhibitor.
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