Download Assn5

Biochemistry 411/602
ASSIGNMENT 5
Due week of April 26
1. Show the biochemical pathway for each of the following:
a) the synthesis of L-proline starting with L-arginine
b) the synthesis of L-cysteine starting with L-methionine
c) the synthesis of L-serine starting with L-asparagine
d) the synthesis of norepinephrine starting with L-phenylalanine
2. How many amino acids are required to synthesize creatine? Draw the structure of creatine
and show the contribution of each to the structure.
3. The biosynthesis of purines and pyrimidines requires 5-phosphoribosyl--pyrophosphate (5’PRPP). Starting with glucose, show how 5’-PRPPis synthesized.
4. Starting with 5’-UMP, show the pathway for the biosynthesis of 2-deoxycytidine-5’monophosphate (5’-dCMP).
5. Describe a biochemical procedure that selectively inhibits DNA synthesis, but has no affect
on RNA synthesis. Answer this question by identifying a compound that inhibits one of the
enzymes you showed in question 4.
5 Point Bonus
1. Beginning with NaNO2, trace the path of nitrogen into the structure of ATP and CTP in lima
beans. List all stable nitrogenous intermediates in the pathways. The final steps should show the
nitrogen donors for each of nitrogen atoms in these molecules. (HINT: Work backwards. You
will use the same donor more then once and in multiple reactions. You need not show the
synthesis of carbon skeletons for Krebs cycle compounds. Be sure you account for all of the
amino group donors)