Nitrogen Metabolism

Question 1

Protein Recommendations

Answer 1

RDA is 56 g/day

Additional liver & kidney strain= gout

Question 2

N equilib

Answer 2

Balance b/t Nitrogen
16% uptake from food
loss in urine, feces etc.

uptake>loss (growth & pregnancy)
uptake< loss (malnutrition, stress)
uptake=loss

NPU (net prot utilization)

Question 3

Essential AA

Answer 3

Arg
His
Ile
Leu
Lys
Meth
Phe
Thr
Trp 
Val 

*not syn by humans

Question 4

Transaminase

Answer 4

not K, T, P

From glutamate from aa and a ketoglutarate

Question 5

Glutamate dehydrogenase

Answer 5

Found in liver mitoch

Release in serum after severe liver damage

Question 6

D amino oxidase

Answer 6

C no longer chiral

2x to O

Question 7

Urea Cycle Failure

Answer 7

Hyperammonemia
Lethargy
Coma
Agitation
Encephalopathy  (Reye syndrome) 

Live cirrhosis- alcoholism, ataxia, slurred speech, tremor, derangements

Treat by replacing essential aa by their ketoacids

Question 8

Metabolic Compensation of acidosis

Answer 8

Glutaminase & glutamate dehydrogenase form NH3

Gluconeogensis from a ketoglutarate binds another 4 H+ to yield Glutamate & CO3 and H+

Question 9

Lysinuric protein intolerance

Answer 9

Defective transporter for dibasic aa in basolateral mem of kidney & intestine

Def in lys, arg & ornithine & reabsorbtion reduced from.

Hyperammonemia & orotic aciduria

Protein restriction & citrulline

Question 10

Hartnup

Answer 10

Defect in taransporter for large netural aa

Trp def, pellagra, encephalopathy

Question 11

Oasthouse disease

Answer 11

def of Met uptake 
Met metabolised by intestinal bac, excreted in kidney

Drying hops smell of urine

Striking white hair, mental retardation etc.

Question 12

Cystinosis

Answer 12

can’t eliminate cystine from lysosomes due to defect in cys/H+ symporter

Destroy kidney, cystine crystals in cornea, retinal blindness,

Cystamine converts cys to mixed di S which can leave lysosomes through lys transporetr.

Question 13

Cystinuria

Answer 13

transporter for lys, arg, ornithine & cyst defect.

Intestianl uptake of di & tri peptides sufficient but fail to reuptake cystine= kidney stones
Neutral to alkali urine (penicillamine) & a large volume

Question 14

BUN

Answer 14

blood urea nitrogen

Urea [ ] in blood as nitrogen
High value could get urea crystals on skin due to excess production/ reduces excretion

Low values- benign but can be due to liver fail, alcohol, malnutrition

Question 15

Ornitine Transcarbamoylase

Answer 15

X linked recessive
Defect in urea cycle when ornithine goes to citrulline
In liver mitochondria

Question 16

Carbamoylphosphate synthetase I

Answer 16

Early & late onset forms when Nitrogen from blood needs to become ornithine
In liver mitochondria

Question 17

Argininosuccinate synthetase

Answer 17

Citrullinemia (builds up)

In liver cytosol

Question 18

Argininosuccinate Lyase

Answer 18

Argininosuccinate aciduria
Treat w/ Arg + Ornitine!
In liver cytosol

Question 19

Arginase

Answer 19

Progressive spastic quadriplegia, mental retardation

Induction w/ Shope papilloma virus?
Arginine going to ornithine & releasing urea!