Amino Acid Metabolism 2:
Amino acid biosynthesis, amino acids are
metabolites, metabolic genetic disorders
Albinism is caused by
mutations in the tyrosinase
It was thought at one time
gene which is required for
that Count Dracula may have
pigment biosynthesis
suffered from porphyria
, Key Concepts in Amino Acid Metabolism
• Plants and bacteria synthesize all twenty amino acids, humans can only
synthesize about half of the twenty amino acids.
• In general, the more complex amino acids are essential amino acids in
humans as they require enzymes that have been lost from the human
genome over evolutionary time.
• The herbicide glyphosate (RoundUp) is an inhibitor of the Shikimate
Pathway responsible for the synthesis of aromatic amino acids.
• Numerous genetic diseases are caused by defects in amino acid
metabolic pathways; genetic diseases can be due to recessive or
dominant mutations.
, Overview of Amino Acid Biosynthesis
The carbon skeletons of all twenty amino acids are derived from just
seven metabolic intermediates, that together, are found in three
metabolic pathways. These include:
1) three glycolytic pathway intermediates; 3-phosphoglycerate,
phosphoenolypyruvate, and pyruvate,
2) two pentose phosphate pathway intermediates; ribose 5-
phosphate and erythrose 4-phosphate
3) two citrate cycle intermediates; -ketoglutarate and
oxaloacetate.
, Overview of Amino
Acid Biosynthesis
Arginine is listed as an essential amino acid
because humans require arginine in their diet to
support rapid growth during childhood and
pregnancy, even though it is made by urea cycle.
Tyrosine is also highlighted because this conditional
nonessential amino acid is made in humans from the
essential amino acid phenylalanine.
Amino acid biosynthesis, amino acids are
metabolites, metabolic genetic disorders
Albinism is caused by
mutations in the tyrosinase
It was thought at one time
gene which is required for
that Count Dracula may have
pigment biosynthesis
suffered from porphyria
, Key Concepts in Amino Acid Metabolism
• Plants and bacteria synthesize all twenty amino acids, humans can only
synthesize about half of the twenty amino acids.
• In general, the more complex amino acids are essential amino acids in
humans as they require enzymes that have been lost from the human
genome over evolutionary time.
• The herbicide glyphosate (RoundUp) is an inhibitor of the Shikimate
Pathway responsible for the synthesis of aromatic amino acids.
• Numerous genetic diseases are caused by defects in amino acid
metabolic pathways; genetic diseases can be due to recessive or
dominant mutations.
, Overview of Amino Acid Biosynthesis
The carbon skeletons of all twenty amino acids are derived from just
seven metabolic intermediates, that together, are found in three
metabolic pathways. These include:
1) three glycolytic pathway intermediates; 3-phosphoglycerate,
phosphoenolypyruvate, and pyruvate,
2) two pentose phosphate pathway intermediates; ribose 5-
phosphate and erythrose 4-phosphate
3) two citrate cycle intermediates; -ketoglutarate and
oxaloacetate.
, Overview of Amino
Acid Biosynthesis
Arginine is listed as an essential amino acid
because humans require arginine in their diet to
support rapid growth during childhood and
pregnancy, even though it is made by urea cycle.
Tyrosine is also highlighted because this conditional
nonessential amino acid is made in humans from the
essential amino acid phenylalanine.
