1. No category

SCH 511 (ASSIGNMENT I)
Q1.
Why is natural product and secondary metabolism so widely variable in the plant
kingdom?
Q2.
Identify the biological reagents A, B and C responsible for the following reaction.
A
R
B
OH
R
O
RR
H
C
O
R
Q3.
CH3
Acetyl-CoA is the precursor in fatty acid biosynthesis. However, for most of the
reactions, acetyl-CoA needs to be further activated by a biotin-dependent enzyme before
it can be used by the fatty acid synthase complex.
O
S
+
CoA
O
ATP
HCO3
Biotin
O
O
S
CoA
Describe the mechanism of the above reaction and give the name of the enzyme for the
above transformation.
Q4.
Draw a mechanism for the conversion of naphthol (1) to its methyl ether (2) by a S-adenosyl
methionine (SAM) dependent enzyme. How might you accomplish this conversion in the
lab?
O
O
HO
MeO
SEnZ
SEnz
SAM
Q5.
1
2
Draw a mechanism for the decarboxylation of (S)-dopa (12) to give dopamine (11) by a
pyridoxal phosphate (PLP) dependent enzyme (NB. PLP = 13, below).
O
O
H2N
H3N
PLP
OH
OH
OH
OH
3
Q6.
4
Draw a mechanism for the condensation of aldehyde 5 with dopamine (6) to give
tetrahydroisoquinoline (7).
H
O
H
H2N
+
OH
5
6
Q7.
HO
OH
OH
N
OH
OH
7
Which of the following compounds is more easily decarboxylated?
O
O
O
O
OR
N
Q9.
N
H
H
Prenylation is a common secondary modification in biosynthesis of secondary
metabolites.
Answer the following based on the transformation given below:
a) Provide a reasonable mechanism for the transformation of 8 and 9 to 10.
b) Give reagent for the transformation of 9 to 10.
c) Show the mechanism for the metabolism of 10 to 11 and 12.
OH
OH
+
PPO
10
9
8
O
OH
O
11
13
OH
O
12