Download Ketogenic amino acids

4. Metabolic classification of amino acids:
according to metabolic fate or degradation products of amino acids
they may be:
Metabolic breakdown of amino acids
• Glucogenic amino acids-carbo n skeletons are broken down to
pyruvate, a-ketoglutarate, succinyl-CoA, fumarate, or oxaloacetate
(glucose precursors).
- TCA cycle intermediates or precursors to be metabolized to CO2, H2O,
or for use in gluconeogenesis.
• Ketogenic amino acids, are broken down to acetyl-CoA, beta hydroxy
butyrate or acetoacetate and therefore can be converted to fatty acids
Both glucogenic and ketogenic amino acids Yield α -ketoglutarate,
pyruvate, oxaloacetate, fumarate, or succinyl-CoA in addition to acetyl
CoA or acetoacetate Isoleucine ,Threonine,Tryptophan ,Phenylalanine
Tyrosine
Amino acid metabolism and central metabolic
pathways
Biomedical importance of amino acids
• The amino acids fulfill vario us functions in the living organism: For
examples: Only the 20 proteinogenic amino acids are included in the
genetic code and therefore regularly found in proteins. The genetic code
is the set of rules by which information encoded within genetic material
(DNA or mRNA sequences) is translated into proteins by living cells.
DNA serves as the genetic blueprint of a cell
• Amino acids or their derivatives are also form components of lipidse. g.,
serine in phospholipids (cell membrane). The amino acid serine , which
has a hydroxyl group side chain provides the head group for the negative
phospholipid, phosphatidyl serine. .
• Several amino acids function as neurotransmitters themselves such as
glycine
and
glutamic
acid,
while
others
are
precursors
of
neurotransmitters, mediators.
Glycine acts as an inhibitory transmitter in spinal cord and medulla
(Adrenal gland).
• Glutamic acid is an excitatory neurotransmitter within the central
nervous system. That carries signals from one nerve to another.
Also glycine in bile salts, bile salts are
conjugated by the liver with glycine and are mainly responsible for the
emulsification of the fats.
Amino acids can be converted to biologically active nitrogenous products
such as creatine phosphate, dopamine, histamine and nitric oxide.
Phosphocreatine is formed from parts of three amino
acids: arginine (Arg), glycine (Gly), and methionine
(Met). Histamine is secreted by basophils and mast cells
as part of a local immune response to the presence of
invading bodies.
The carbon chains of amino acids after deamination are a good
source of energy.
- Amino acid as a central metabolic pathways: specific amino acids form
precursors for other metabolites e. g., for glucose in gluconeogenesis, for
purine and pyrimidine bases in nucleic acid synthesis, heme in
hemoglobin, and for other molecules.