Download Review Problems #2 (Enzyme Review, Phosphatases

Review Problems For week 9.
We will definitely not get through all of these, but it is useful to have them in one place.
1) Outline the chemical intermediates in the degradation of the following amino acids:
Asn, Asp. What cofactor(s) play a role in this process? What other end product may be
formed from Asp. What cycle does this come from?
2) What amino acids are degraded to yield alpha-ketoglutarate?
3) Outline the chemical intermediates in the conversion of histidine to glutamate. What
cofactor serves as the acceptor for the amidine group of imidazole ring of histidine?
What other cofactors are typical one carbon acceptors/transfer agents?
4) Outline the steps in the conversion of proline and arginine to glutamate.
5) Draw the structure of S-adenosylmethionine. How is this molecule formed? What is
its biological function?
6) Methionine is degraded to a four carbon molecule- outline the steps in this conversion.
What other amino acid is required for this transformation? What amino acid is
synthesized in this process?
7) The four carbon molecule derived from methionine is coverted into a Krebs cycle
intermediate. What is this molecule? What cofactors are involved in this transformation?
8) Outline the degradative pathway for leucine. What steps in this pathway are akin to
steps involved in fatty acid oxidation or synthesis. Are they more similar to fatty acid
oxidation, or synthesis?
9) Show the intermediates involved in the degradation of valine and isoleucine.
10) Name the cofactor required for hydroxylation of phenylalanine. Draw the structures
of the three commonly observed forms of this cofactor. How are they related?
11) What is the consequence of a deficiency in phenylalanine hydroxylase?
12) What is the major difference(s) between monooxygenases and dioxygenases?
13) Why is hydroxylation of an aromatic ring a necessary precursor to its cleavage?
14) What are the two major degradation products of phenylalanine/tyrosine?
15) What are the two major degradation products of tryptophan?
16) What are the ultimate biological molecules that act as acceptors of ammonia (not the
transfer of an amino group) in higher organisms? What enzymes mediate this(ese)
transformation(s)? What are the energetic requirements for this(ese) reaction(s)?
17) Draw mechanisms for the following reactions:
a) Conversion of threonine to acetaldehyde and glycine
b) Conversion of threonine to glycine and acetyl CoA
c) Conversion of threonine to succinyl CoA
d) Conversion of cysteine sulfinate to pyruvate and sulfur dioxide. How is cysteine
sulfinate synthesized?
e) Conversion of glycine to formaldehyde and carbon dioxide
18) Formaldehyde is formed in the degradation of a number of amino acids. Which are
these? How is formaldehyde trapped and carried in biochemistry? (structures please)