NITROGEN METABOLISM AND AMINO ACID REGULATION

what is the nitrogen intake and excretion levels when the animal is in nitrogen balance

nitrogen intake and excretion are equal

what is the nitrogen intake and excretion levels when the animal is positive in nitrogen balance

nitrogen intake is greater than nitrogen excretion

when is the animal normally in positive nitrogen balance

during growth or pregnancy

what is the nitrogen intake and excretion levels when the animal is said to be negative in nitrogen balance

nitrogen intake is less than nitrogen excretion

what is an example of endogenous proteins

muscle protein

what sources can contribute to the amino acid pool

endogenous protein (using aa from body muscles) and dietary protein

define deamination

the removal of amine form an animo acid

what are the a-keto acids produced by deamination of amino acids used for

the catabolic and anabolic reactions (can be converted into glucose or lipids)

what happens to endogenous protein in positive and negative nitrogen balance

positive nitrogen balance - more endogenous protein is made

negative nitrogen balance - endogenous protein is used up

what happens when ammonia groups build up in concentration within the blood

it becomes toxic

how can ammonia be excreted in fish / reptiles and birds/ mammals

fish - ammonia gas

reptile and birds - uric acid

mammals - urea

define transamination

Transfer of the amine group from an amino acid and a-keto glutarate to make a a-keto acid and glutamate

what is the amino acid produced when an amino acid is deaminated and this deamination also releases an a-keto acid

glutamate

what is glutamate converted into

glutamine

how is glutamate converted into glutamine

by the addition of an ammonium group

why is glutamate converted into glutamine

because it can travel in the blood where it is then taken to the Liver

what happens to glutamine when it enters the liver

it is deaminated

what is glutamine deaminated into

glutamate and ammonium

describe the whole process starting at the amino acid pool until the formation of urea in the liver

- Deaminate an amino acid from the AA pool to make a- ketoglutarate, adding the amine group to the a-ketoglutarate to make glutamate = transaminations reaction

- Purpose of this is to release the a-keto acid to be used in catabolic and anabolic reactions

- Add another ammonium group to the glutamate to form glutamine which can travel in the blood to the liver, where the glutamine is broken down into glutamate and the ammonium group and then glutamate can be broken down again into a- ketoglutarate and release two overall ammonium groups which will bind with CO2 in the urea cycle to form urea which is then excreted

why is the urea cycle energetically expenisive

it uses 4 ATPs to produce 1 urea molecule

when in ammonia added in the urea cycle

once in the beginning with CO2 and then another time with aspartate to then go on more subsequent reactions to form UREA

what happens if the urea cycle isn't working correctly

this can lead to ammonia build up

what can a build up of ammonia do to glutamate dehydrogenase

cause the usage of a-ketoglutarate which is a key intermediate in the krebs cycle

what is the physiological consequence of a-ketoglutarate being used up

The use of a-ketoglutarate causes the Krebs cycle to be depleted of intermediates so the ability of the cell to produce ATP is decreased. Causing CNS defects due to defect in energy production

what neurotransmitter does the build up of ammonia also affect

glutamate

what happens to glutamate during the build up of ammonia

glutamate is converted into glutamine

because the conversion of glutamate into glutamine will reduce the levels of this neurotransmitter what will this lead to

defects in the central neural nervous system

what are clinical signs of ammonia build up

vomiting

intolerance to high foods

mental retardation

coma and death

what can sometimes cause issues in the urea cycle which lead to ammonia build up

genetic effect in urea cycle enzymes which are rare or liver disease or liver damage

what are treatment methods

low protein food meals

with little amounts of feed at frequent intervals

what are glucogenic amino acids

amino acids that can be used to make glucose by deaminating them to produce pyruvate, OAA or a-ketglutarate