Download Due: 2015. 10. 12. 11:00 am (월)

응용생화학 HW #2 (100 points)
Due: 2015. 10. 12. 11:00 am (월)
1. (10 points)
(a) Enzyme can be classified into 6 groups. Briefly explain about each group.
(b) Classify the enzyme listed below according to above explanation.
(Hexokinase,
Pyruvate
dehydrogenase,
Galactosyltransferase,
Lysozyme,
Glucose-1-
Phosphate epimerase, Fructose bi-phosphate aldolase, Pepsin, Cytochrome oxidase)
2. (20 points)
Derive the Michaelis-Menten kinetics using (a) steady state approximation and
(b) chemical equilibrium hypothesis.
(c) Write down physical meaning of Km and kcat
(d) How do you call (kcat/Km), and what is its physical meaning
3. (20 points) Explain about terms below in short sentences.
(a) MHC protein
(b) O-glycan and N-glycan
(c) Antibody, variable regions and constant regions. (Draw typical structure of Ab)
(d) Cooperative kinetics and Hills’ coefficient
4. (10 points) Explain about Line-Weaver Bulk plot. What is the weakness of
the Line-Weaver Bulk plot?
5. (20 points)
The kinetics of allosteric enzymes usually does not fit on Michaelis-Menten
equation because modulator (regulator) that binds to the enzyme changes the
activity on the substrate(S). Thus there are two states, R and T state. A model that
hypothesizes the existence of equilibrium between the two state (L=[T]/[R]) is called
Concerted model (or MWC model). Allosteric enzymes fit on this model.
Let’s assume that there is an allosteric enzyme with one binding site for the
substrate, S. And it binds 100 times better on R state (c=KT/KR=100, KT, KR is
dissociation constants). If one mole of substrate binds to one mole of the enzyme
with one to one ratio, calculate how much L can be changed by the one mole of
substrate.
6. (10 points)
There are two enzymes (i.e. kinase) for the phosphorylation of glucose(S). One has
its conformation complementary to glucose and the other has its conformation
complementary to phosphorylated transition state of glucose. Compare the two
enzymes in terms of Gibbs free energy according to reaction coordinate (Draw free
energy profile.). Which enzyme is more feasible for the reaction?
7. (10points)
Explain the mechanism of the chymotrypsin. Include,
a) Catalytic triad
b) Hydrogen bonding between substrate and amino acids and acyl bond formation
in initial stage of the reaction.
c) Tetrahedral intermediate