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Berg • Tymoczko • Stryer     Biochemistry               Sixth Edition         Chapter 24:The Biosynthesis of Amino Acids  ...
BIOSYNTHESIS OF AMINO             ACIDS   All amino acids are synthesized from    intermediates of Glycolysis, TCA or PPP...
Several enzyme cofactors play importantroles in amino acid metabolism    One carbon transfer is very important     – Biot...
Tetrahydrofolate carriesactivated 1-C units atseveral oxidation levels
SAM is more commonly used for CH3 transfer.
Cys is made from Ser and HomoCys   Sulfur comes from homoCys   The C skeleton comes from Ser   High homocysteine levels...
Amino acids are precursors of    many biomolecules   Glutathione (GSH)   Nitric oxide (NO)
GSH serves as a buffer and antioxidant   Protects cells from oxidative damage   Presents at high levels (5 mM)   It cyc...
2 GSH + RO OH GSSG + H2O + ROH
Nitric oxide is formed from Arg   NO is an important messenger   It is made by NO synthase   NADPH and Oxygen are requi...
Amino acids are converted to       specialized products   Porphyrins and bile pigments    –   Biosynthesis of porphyrins ...
Other specialized products   Creatine   Histamine   Serotonin   Catecholamines    –   Dopamine    –   Norepinephrine  ...
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
Lec14 amino synt
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Lec14 amino synt

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Transcript of "Lec14 amino synt"

  1. 1. Berg • Tymoczko • Stryer Biochemistry Sixth Edition Chapter 24:The Biosynthesis of Amino Acids Copyright © 2007 by W. H. Freeman and Company
  2. 2. BIOSYNTHESIS OF AMINO ACIDS All amino acids are synthesized from intermediates of Glycolysis, TCA or PPP. Different organisms vary greatly in their ability to synthesize the 20 amino acids. Amino acids are grouped by their metabolic precursors.
  3. 3. Several enzyme cofactors play importantroles in amino acid metabolism  One carbon transfer is very important – Biotin – Tetrahydrofolate – S-adenosylmethionine (SAM)
  4. 4. Tetrahydrofolate carriesactivated 1-C units atseveral oxidation levels
  5. 5. SAM is more commonly used for CH3 transfer.
  6. 6. Cys is made from Ser and HomoCys Sulfur comes from homoCys The C skeleton comes from Ser High homocysteine levels are associated with vascular diseases • Coronary heart disease • Arteriosclerosis The molecular basis of the disease ??? • It appears to damage cells lining blood vessels and to increase the growth of vascular smooth muscle cells
  7. 7. Amino acids are precursors of many biomolecules Glutathione (GSH) Nitric oxide (NO)
  8. 8. GSH serves as a buffer and antioxidant Protects cells from oxidative damage Presents at high levels (5 mM) It cycles between a reduced form (GSH) and an oxidized form (GSSG) GSSG is reduced to GSH by GSH reductase The ratio of GSH to GSSG is greater than 500 in most cells. GSH plays a key role in detoxification by reacting with hydrogen peroxide and organic peroxides. Glutathione peroxidase is remarkable in having a modified amino acid containing Se.
  9. 9. 2 GSH + RO OH GSSG + H2O + ROH
  10. 10. Nitric oxide is formed from Arg NO is an important messenger It is made by NO synthase NADPH and Oxygen are required
  11. 11. Amino acids are converted to specialized products Porphyrins and bile pigments – Biosynthesis of porphyrins • Formation of ALA • Formation of porphobilinogen Porphyrias – Congenital erythropoietic porphyria
  12. 12. Other specialized products Creatine Histamine Serotonin Catecholamines – Dopamine – Norepinephrine – Epinephrine Melanin Thyroid Hormones
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