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Name__________________________ (1 pt)
CH 110
Partners Name _______________________(1 pt)
120 pts
T A _______________________________
April 22/25, 2008
50 minutes
Work Shop 04
YOU ARE FREE TO COLLABORATE WITH YOUR PARTNER AND MAY ASK QUESTIONS OF YOUR
TEACHING ASSISTANT. ANSWER EACH OF THE QUESTIONS IN THE SPACE PROVIDED.
12 pts 1) Diagram the general steps in an enzyme mechanism, then explain generally but in some detail how
an enzyme converts a free substrate molecule into a free product molecule:
44 pts 2) A protein will be least soluble in water when the pH = _____. The interaction of a protein side group
which is acidic with one which is basic will form a ___________. Cysteine residues stabilize tertiary
protein structure by forming: _______________________ . A group of hydrophobic side-groups on a
protein will cause the chain to _____________________________________. A group of hydrophylic
side-groups on a protein will cause the chain to ______________________________________. The
secondary structure of a protein has hydrogen bonds between what two entities in the peptide grouping:
__________________________________________________________. An a-helix has the hydrogen
bond between which aminoacid residues? _____________________________________
(circle)
lipids carbohydrates
Enzymes are
proteins . A cofactor is _________________________________ .
The name of an enzyme tells _________________________ . The following are enzyme names, what
do these enzymes do? Isomerase ____________________ Hydrolase ________________________
Transferase ________________________ Lyase _________________________ What specifically
does an acetylcholineesterase enzyme do? ______________________________________________ .
Explain in terms of structure why enzymes work best over very narrow ranges of pH and temperature:
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________ .
Explain briefly the “lock & key” mechanism of enzyme specificity: ____________________________
_________________________________________________________________________________
_________________________________________________________________________________
__________________________________________________________________________________ .
Workshop 04
Page 2
30 pts 3) a) Digest the tetrapeptide below into its component amino acids using strong ACID (HCl(aq), form!!):
b) Name each of the amino acids and indicate whether the side groups are nonpolar, polar neutral, acidic, basic.
O
O
O
O
H3NCHCNHCHCNHCHCNCHCO
CH2 CH2 CH2
CH2 CH2 CH2
CH3
C
CNH2
O O
O
CH2
HO CH
HCl
H2O
c) What will be the likely pI of the above tetrapeptide? _____ Is this tetrapeptide predominately hydophylic
hydrophobic (circle)? Will this peptide give a positive: Biuret test? ______ ; Xanthopoetic test? ______
32 pts 4) Describe or define each of the following:
a) Primary structure of a protein:
b) Secondary structure of a protein::
c) Tertiary structure of a protein:
d) Quaternary structure of a protein:
e)How does a competitive enzyme inhibitor work?
f) How does an allosteric enzyme inhibition/stimulation (regulation) work?
g) Make a β-glycosidic linkage with the aminoacid residue:
HO
H2COH
O
OH
HO
HN
O C
CH3
O
+
C O
H N C CH2 C H
H
NH
h) Draw and explain the general features of tertiary structure of a protein (taking a random coil shape) when it
consists of five approximately equal length regions in which three regions are hydrophobic and the other two
region is hydrophilic in nature when placed in contact with water:
H2O
hydrophobic hydrophylic hydrophobic hydrophylic hydrophobic