Amino
Acid Metabolism
Catabolism
1) Constant
body turnover (75% reused for protein synthesis; 5% catbolized)
2) AA in
excess of requirements
3) non-limiting
AA are catabolized
4) AA for
energy production ~20% of daily energy requirement (normal)
Deamination - removal
of amino group as amonia
Transamination - Transfer of amino group from a compound to another
Ketogenic AA ® acetyl-CoA
1. leucine
2. isoleucine
3. phenylalanine
Gluconeogenic AA
All other AA - phenylalanine is both
Ammonia Toxicity:
Symptoms:
1. muscle
tremors
2. slurred
speech
3. blurred
vision
4. ataxia,
incoordination
5. tetany,
violent spasms
6. comotose
state
7. death -
accute = 30 min.; or could take days
Urea Cycle
1. Ammonia detoxification
2. N for
urea synthesis enters as NH3 (from deamination)
3. Requires
4 high energy phosphate bonds per urea molecule
4. Fate of
urea in blood (BUN) - blood urea nitrogen
a. urine
b. rumen - via saliva
c. cecum
b. & c. are
recycling
Birds - use
uric acid as excretory product - requires glycine
Ruminants = recycle
urea to rumen (horse to cecum??)