Molecular Biochemistry II

Amino Acid Catabolism - Carbon Skeletons


Textbook Reading: Voet & Voet, Biochemistry, 3rd Edition, p. 921-927, 995-1013, 1027-1030.

Some recent articles (optional reading): 
P. F. Fitzpatrick (1999) "Tetrahydropterin-Dependent amino acid hydroxylases," Annu. Rev. Biochem. 68: 355-391.
P. A. Frey (2001) "Radical mechanisms of enzymatic catalysis," Annu. Rev. Biochem. 70: 121-148.
D. Thomas, A. Becker & Y. Surdin-Kerjan (2000) "Reverse methionine biosynthesis from S-adenosylmethionine in eukaryotic cells," J. Biol. Chem. 275: 40718-40724.
J. M. Mato, F. J. Corrales, S. C. Lu & M. A. Avila (2002) "S-Adenosylmethionine: a control switch that regulates liver function," FASEB J. 16: 15-26.
R. Banerjee & S. W. Ragsdale (2003) "The many faces of vitamin B12: Catalysis by cobalamin-dependent enzymes," Annu. Rev. Biochem. 72: 209-247.
R. Banerjee (2003) "Radical carbon skeleton rearrangements: catalysis by coenzyme B12-dependent mutases," Chem. Rev. 103: 2083-2094.
T. Toraya (2003) "Radical catalysis in coenzyme B12-dependent isomerization (eliminating) reactions," Chem. Rev. 103: 2095-2127.
P. J. Stover (2004) "Physiology of folate and vitamin B12 in health and disease," Nutrition Rev. 62: S3-S12.
M. Fontecave, M. Atta & E. Mulliez (2004) "S-Adenosylmethionine: nothing goes to waste," Trends in Biochem. Sci. 29: 243-249.
M. Yamanishi, M. Vlasie & R. Banerjee (2005) "Adenosyltransferase: an enzyme and an escort for coenzyme B12?" Trends in Biochem. Sci. 30: 304-308.
L. Randaccio, S. Geremia & J. Wuerges (2007) "Crystallography of vitamin B12 proteins," J. Organometallic Chem. 692: 1198-1215.

Potential Test Questions:

1.a. Write out the reaction cycle by which methionine is converted to S-adenosylmethionine (SAM), and methionine is regenerated by a pathway involving methyl transfer from N5-methyl-tetrahydrofolate. Include structures of intermediates and indicate what additional vitamin-derived cofactor participates in the regeneration of methionine.
b. Draw the substrates and products of any one reaction that utilizes SAM as a methyl group donor.

2. Write out the reaction catalyzed by Phenylalanine Hydroxylase, giving structures of substrates and products and indicating (by name only) cofactors involved in providing reducing equivalents to the reaction. What are the biochemical and physiological consequences of genetic deficiency of the Phenylalanine Hydroxylase enzyme? What amino acid becomes a dietary essential in this disease? Why are skin and hair color affected in this disease? Summarize and explain the usual treatment for this condition.

Copyright 1998-2007 by Joyce J. Diwan. All rights reserved.

Lecture notes on
Amino Acid Catabolism: C

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Amino Acid Catabolism: C

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