Nitrogen Turnover Flashcards
1
Q
nitrogen compoounds are degraded into mostly
A
- urea
- urea levels are the only thing that changes in excretion with regards to proteins intake
2
Q
excretion in urine comes in four forms
A
- ammonia
- urea
- uric acid (purine breakdown product)
- creatinine (proportional to muscle mass)
3
Q
balance of nitrogen in the body
A
- intake from protein in the diet
- goes into amino acid pool and can then be used for body protein or made into urea and excreted
- if you are in a positive balance you will have more going to body protein than you are excreting
- during times of insufficient protein, you have more going back into the amino acid pool from the body protein and that is being made into urea
4
Q
tramua and urea balance
A
- high energy requirement
- a lot more going into the amino acid pool and being made into urea
5
Q
what are the 3 steps of removin nitrogen
A
- transfer to a common carrier
- ammonia is regenerated in the liver
- ammonia is incoporated into urea
6
Q
what is a common carrier of nitrogen
A
-alpha ketogluterate which then turns into glutamate
7
Q
PLP
A
- is used by aminotransferase in order to transfer a nitrogen from an amino acid a common carrier
- arises from VB6
- exhanges a keto group fro a amine group
8
Q
glutamate dehydrogenase
- location
- function
- what happens to its product in the liver
- cofactors
A
- this is located in the mitochondria and is fundamental for the release of ammonia so it can be acted on by CPSI to create carbamoyl phsophate for the urea cycle
- in liver, the ammonia produced can be incorporated into urea
- urea production is significant only in the liver
- uses NAD or NADP as cofactors
9
Q
regulation of glutamate dehydrogenase
A
- activity increased by ADP and GDP
- activity decreased by ATP and GTP
10
Q
what is ammonia produced from on asparagine and glutamine
A
-amide groups
11
Q
minor way to dispose of ammonia
A
- make glutamate by running the glutamate dehydrogenase reaction in reverse
- this is when the urea cycle is saturated
12
Q
major way of disposing of ammonia
A
- make glutamine via the glutamine synthase reaction
- used to fix ammonia especially in the brain; also occurs in muscle, lungs, and adipose tissue
- glutamine is a majr carrier of n in the blood
- glutamine levels increase after a protein rich meal
13
Q
problem with hyperammonemia in children
A
- glutamate can only hold so much ammonia as glutamine before it maxes out and the body runs out of glutamine
- when this happens, hyperammonemia will present and this can cause serious health problem (especially in the brain)
14
Q
urea cycle order and mnemonic
A
- ordinarily careless crappers are also frivolous about urination
- ornithing, carbamoyl phosphate, citrulline, aspartate, arginosuccinate, fumarate, arginine, urea
15
Q
CPSI
A
- founds in the mitochondria
- needs NAG to function
- NAG is made by NAG synthase using acetyl-CoA and glutamate
- NAG synthase uses arginine
- produces carbamoyl phosphate from NH4 which comes from the glutaminase and glutamate DH reactions
