Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology

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This exam paper must not be removed from the venue


School of Chemistry and Molecular Biosciences
EXAMINATION
Semester Two Final Examinations, 2018
CHEM2052 Chemical Biology
This paper is for St Lucia Campus students.
Examination Duration: 120 minutes
Reading Time: 10 minutes
Exam Conditions:
This is a Central Examination
This is a Closed Book Examination - specified materials permitted
During reading time - write only on the rough paper provided
This examination paper will be released to the Library
Materials Permitted In The Exam Venue:
(No electronic aids are permitted e.g. laptops, phones)
Calculators - Casio FX82 series or UQ approved (labelled)
A simple unassembled molecular model building kit in an unmarked container is
permitted
Materials To Be Supplied To Students:
1 x 14-Page Answer Booklet
Instructions To Students:
Additional exam materials (eg. answer booklets, rough paper) will be
provided upon request.
Answer Part A on the examination paper.
Answer Part B in a separate answer booklet.

Venue ____________________
Seat Number ________
Student Number |__|__|__|__|__|__|__|__|
Family Name _____________________
First Name _____________________
For Examiner Use Only
Question Mark
A1

A2

A3

A4






Total ________
Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology

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SECTION A
ANSWER THIS SECTION ON THIS EXAMINATION PAPER IN THE SPACES PROVIDED.
TOTAL FOR SECTION A: 30 MARKS
Question A1.
Chlorpromazine was the first drug developed with specific antipsychotic action. The
partial scheme below shows metabolism of chlorpromazine.
N
S
N
Cl
N
S
NH2
Cl
N
S
N
Cl
HO
N
S
NH2
Cl
OS-O
O
O
Phase:___
Flavin Containing Monooxygenase
Phase:___
Enzyme:_________
Chlorpromazine
Metabolite 2
Metabolite 1
Metabolite 3
Metabolite 4
HO
Phase 2
Enzyme:___________
Metabolite 5
Phase:___
Enzyme:_____________
Phase:___
Enzyme:___________

(a) On the scheme shown above:
i. Indicate which of the metabolic reactions are Phase 1 and which are Phase 2 in
the spaces provided.
ii. Give the missing names of the enzymes most likely to be involved in catalysing
each step in the spaces provided.
(4 marks)
Question A1 continues over page
Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology

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(b) On the scheme, draw a possible structure for metabolite 1 in the appropriate box.

(1 mark)
(c) Metabolite 3 reacts further by action of Phase 2 metabolic enzymes to give
metabolite 5. Give ONE (1) Phase 2 reaction which could occur on metabolite 3 by
drawing in the appropriate box on the scheme a possible structure of metabolite 5.
Name the enzyme that could achieve this transformation. Do not abbreviate the
name of the enzyme.
(3 marks)
(d) Suggest a modification you could make to the structure of chlorpromazine to
prevent formation of metabolite 2. Justify your answer.





(2 marks)


[Total A1: 10 marks]









Questions continue over page
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Question A2.
Stavudine is a drug designed to target HIV reverse transcriptase.



(a) What does reverse transcriptase do in the lifecycle of HIV?






(1 mark)


(b) Stavudine is an antimetabolite. Define what an antimetabolite is and explain how
stavudine acts as an antimetabolite.















(3 marks)


Question A2 continues over page
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(c) Give TWO (2) challenges of developing HIV therapeutics and a strategy for
overcoming ONE (1) of these challenges.





















(4 marks)
[Total A2: 8 marks]

Question A3.
Describe TWO (2) strategies enzymes use to lower the activation energy of a reaction.








[Total A3: 4 marks]
Questions continue over page
Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology

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Question A4.
A Lineweaver-Burk double reciprocal plot is shown below. Use this plot and the data given
to answer the following questions.



(a) Calculate Vmax and KM for the uninhibited enzyme.














(2 marks)

Question A4 continues next page


y = 48.38x + 1.04
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
-0.060 -0.040 -0.020 0.000 0.020 0.040 0.060 0.080 0.100 0.120
1/
v 0
(m
in
/m
M
)
1/[S] mM-1
Lineweaver-Burke Plot
[I] = 0
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(b) Calculate kcat for this enzyme. Give your answer in s–1.






(2 marks)


(c) Calculate the catalytic efficiency of the enzyme.



(2 marks)

(d) Add the data supplied in the table below for the inhibited enzyme onto the
Lineweaver-Burk plot already supplied. This data indicates what type of inhibitor?
Justify your answer.
1/v0 (mM/min for 0.001 μM of Enzyme)
[S] (mM) [I] = 0 mM [I] = 5 mM
10 0.17 0.13
20 0.29 0.18
30 0.38 0.22
40 0.43 0.24

Type of inhibitor: ____________________________
Justification:


(2 marks)
[Total A4: 8 marks]

THIS CONCLUDES SECTION A.
SECTION B COMMENCES ON THE NEXT PAGE.
Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology

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SECTION B
ANSWER THIS SECTION IN THE ANSWER BOOKLET PROVIDED.
TOTAL FOR SECTION B: 30 MARKS
Question B1.
(a) The molecule with the structure below has been used for in vivo fluorescent
imaging, where it shows selectivity for a specific metal ion. Name that ion and its
oxidation state. Is this a turn-on or a turn-off sensor? Justify your answers with
reference to the structure of the fluorescent sensor.

(4 marks)
(b) Explain the advantages of ratiometric fluorescent sensors for in vivo imaging of metal
ion distribution over intensity-based probes.

(6 marks)
[Total B1: 10 marks]

REMEMBER: WRITE ALL ANSWERS FOR SECTION B IN THE EXAMINATION BOOKLET,
NOT ON THE EXAMINATION PAPER.





Questions continue over the page.
Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology

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Question B2.
The Histatin-5 peptide is an antimicrobial peptide found in human saliva which binds
Cu2+.
A truncated form of the peptide, called H7A was made with the following amino acid
sequence:
DSHAKRAHGYKR
(a) A solution of the Cu-H7A peptide complex was found to absorb maximally at 530
nm, with an absorbance of 0.080 for a 1 mM solution. What is the extinction
coefficient at 530 nm of the Cu-H7A peptide complex? Show all working.
(2 marks)

(b) The copper(II) ion was shown to be coordinated through the first three residues,
with an N4 donor set in a square planar configuration. Draw the structure of the
metal binding site, showing the first 3 amino acid residues in full. Fully justify how
you arrived at this structure, including any calculations.
(6 marks)
(c) The full length histatin-5 peptide has a second metal binding site for Cu(I) ions of
two adjacent histidine residues. Explain briefly why visible spectroscopy is not
useful for characterising this metal-binding site.
(2 marks)

[Total B2: 10 marks]

Question B3.
Explain the roles of the proximal and distal histidines in the function of haemoglobin.
Include a diagram in your answer.
[Total B5: 5 marks]




Questions continue over page
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Question B4.
Carboplatin reacts around 109 times slower with glutathione than cisplatin. Explain this.
(The structure of glutathione is shown below.)


[Total B6: 5 marks]









END OF EXAMINATION
Data sheet pages and periodic table on following pages.


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DATA SHEET
THE FOLLOWING INFORMATION MAY BE USEFUL IN ANSWERING QUESTIONS IN THIS
EXAMINATION.
These sheets can be separated from the exam paper but NOT removed from the
examination venue.
The structures of the 4 nitrogen bases found in DNA are given below:



The truncated structure of the cofactor NAD+ / NADP+ is shown below:



0 max
M M
[E ][S] V [S]
(K +[S]) (K [S])
catkv = =
+

M
max max
K1 1 1
V [S] Vv = × +

Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology

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2
2
2
max Cu
(C=O / H O)
( )
(COO )
(NH )
(deprot. pept. N)
= 1000 / [0.294 0.434 0.346 0.460 0.494 ] nm
where
λ +
−
+ + + +
=
=
=
=
=
imidazole
a b c d e
a n
b n
c n
d n
e n




Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology
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Essential Amino Acid Structures with three and one letter codes.
Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology
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Semester Two Final Examinations, 2018 CHEM2052 Chemical Biology
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1
H
1.008

The Periodic Table of the Elements
2
He
4.003
3
Li
6.941
4
Be
9.012


5
B
10.81
6
C
12.011
7
N
14.007
8
O
15.999
9
F
18.998
10
Ne
20.179
11
Na
22.989
12
Mg
24.305
13
Al
26.981
14
Si
28.085
15
P
30.974
16
S
32.066
17
Cl
35.453
18
Ar
39.948
19
K
39.098
20
Ca
40.078
21
Sc
44.955
22
Ti
47.88
23
V
50.941
24
Cr
51.996
25
Mn
54.938
26
Fe
55.847
27
Co
58.933
28
Ni
58.69
29
Cu
63.546
30
Zn
65.39
31
Ga
69.72
32
Ge
72.61
33
As
74.922
34
Se
78.96
35
Br
79.904
36
Kr
83.80
37
Rb
85.468
38
Sr
87.62
39
Y
88.906
40
Zr
91.224
41
Nb
92.906
42
Mo
95.94
43
Tc
(98)
44
Ru
101.07
45
Rh
102.905
46
Pd
106.42
47
Ag
107.868
48
Cd
112.41
49
In
114.82
50
Sn
118.710
51
Sb
121.757
52
Te
127.6
53
I
126.904
54
Xe
131.29
55
Cs
132.905
56
Ba
137.33
57
La
138.905
72
Hf
178.49
73
Ta
180.948
74
W
183.85
75
Re
186.207
76
Os
190.2
77
Ir
192.22
78
Pt
195.08
79
Au
196.966
80
Hg
200.59
81
Tl
204.383
82
Pb
207.2
83
Bi
208.980
84
Po
(209)
85
At
(210)
86
Rn
(222)
87
Fr
(223)
88
Ra
226.025
89
Ac
227.028
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Nh
114
Fl
115
Mc
116
Lv
117
Ts
118
Og











58
Ce
140.12
59
Pr
140.908
60
Nd
144.24
61
Pm
(145)
62
Sm
150.36
63
Eu
151.96
64
Gd
157.25
65
Tb
158.925
66
Dy
162.50
67
Ho
164.930
68
Er
167.26
69
Tm
168.934
70
Yb
173.04
71
Lu
174.97








90
Th
232.038
91
Pa
231.036
92
U
238.029
93
Np
237.048
94
Pu
(244)
95
Am
(243)
96
Cm
(247)
97
Bk
(247)
98
Cf
(251)
99
Es
(252)
100
Fm
(257)
101
Md
(258)
102
No
(259)
103
Lr
(260)

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