Chemistry 3410
Quiz 1, October 2006
S. V. Pansare
Time: 75 min
Name:_________________________
Marks
1) a) What products (draw structures) would result from the complete hydrolysis of the tripeptide
Cys-Val-Pro?
[4]
HS
H
N
H3N
O
CO2
N
O
Cys-Val-Pro
.
b) Would the hydrolysis products of the tripeptide Pro-Val-Cys be the same or different?
2) Draw the structure of each of the following amino acids at the specified pH.
O
H2N
OH
NH2
CO2H
at pH 2
H2N
CO2H
at pH 14
H2N
Explain.
[3]
CO2H
N
H
at its pI
3) Consider the sugar D-Idose
HO
H
HO
H
CHO
H
OH
H
OH
CH2OH
D-Idose
a) Draw the Fisher projection for L-Idose
[2]
b) Draw the Haworth structures for ethyl α-D-idopyranoside and and ethyl β-D-idopyranoside.
2
[3]
4) α-Amino acids can be made by treating an aldehyde with ammonia and hydrogencyanide, followed by
acid catalyzed hydrolysis.
a) Give the structures of the two intermediates formed in this reaction
b) What aldehyde would be needed to prepare valine (Val in question 1)?
[3]
5) β-Gentiobiose is found in saffron. It contains two D-glucose molecules linked by a β-1,6-glycoside
bond.
a) Draw the structure of α-gentiobiose.
H
HO
H
H
CHO
OH
H
OH
OH
CH2OH
D-glucose
b) Would gentiobiose be a reducing sugar? Why or why not?
[3]
6) Provide the structure of the major products expected form the following reactions:
D
H
D
'reducing'
enzyme
+
O
3
[8]
+
N
R
(NADH analog)
O
Ph
HCl, MeOH
+
_
CO2
H3N
OH
O
HO
OH
O
Cl
base
HCl, EtOH
excess CH3I
OH
Ag2O
OH
O
O
N
H
CF3COOH
CO2CH3
HN
O
Ph
H2, Pd/C
CH2Cl2
MeOH
O
7 a) Provide a mechanism for the following reaction
[4]
S
N
H
NH
O
i) Br C N
ii) HCl, H2O
N
H
O
O
+
H3N
Cl