General Protein Metabolism Revision

Question 1

celiac disease is due to eating and symptoms

Answer 1

gluten, can affect intestine and prevent absorption of nutrients

Question 2

glutamine

Answer 2

glutamate + ammonia

Question 3

transamination takes place in and requires

Answer 3

cytosol and mitochondria of all tissues especially liver and requires plp (vit b6)

Question 4

all amino acids can be transaminated except

Answer 4

proline, hydroxyproline, lysine, threonine

Question 5

AST and ALT in diseases

Answer 5

ALT and AST - viral hepatitis and toxic injury

AST: non hepatic disease such as myocardial infarction and muscle disorders (bc ALT is more specific to liver)

Question 6

L amino acid oxidase vs D amino acid oxidase vs L-glutamate dehydrogenase
carrier
action
site
actiivty
reversibility

Answer 6

L amino acid oxidase
FMN, Oxidation forming imino acid then acids water and removes ammonia to form alpha keto acid, Liver & Kidney, Low activity, irreversible
D-amino acid oxidase
FAD, Oxidation forming imino acid then adds water and removes ammonia forming alpha keto acid. Liver & Kidney, high activity, irreversible.
L-glutamate dehydrogenase
NAD(P), oxidation forming alpha imino glutamate then adds water and forming ammonia forming a keto glutamate, high activity, reversible

Question 7

reversal of transdeamination

Answer 7

reductive lamination

Question 8

sources & fates of ammonia

Answer 8

source: 1. deamination of amino acids, deamination of purines and pyrimidines, bacterial putrefaction in intestine
fate: anabolic: synthesis of non essential amino acids from reductive lamination and synthesis of glutamine
1. liver - 95% forms urea and goes to kidney then urine. 5% converted to glutamine
2. brain- forms glutamine then transported to liver to be converted to urea
3. kidney- excreted to urine - 60% from glutamine - 40% deamination of amino acids
4. muscle- ammonia converted to alanine by ALT then transported to liver (glucose alanine cycle) then converted to urea in liver

Question 9

pathways that occur in mitochondria and cytosol

Answer 9

HUG
Heme Synthesis
Urea Cycle
Gluconeogenesis

Question 10

pathways that take place in liver only

Answer 10

ironic acid pathway (cytosol), urea cycle

Question 11

requirements for urea synthesis

Answer 11

2 amino groups - 1 from free ammonia and 1 from aspartate
CO2
4 high energy bonds

Question 12

CPS 1

Answer 12

glutamine + acetyl coA = NAG (N acetyl glutamine) which activated CPS1 so CO2 + NH3 = carbamoyl phosphate.

arginine which is found in protein rich meals activates synthesis of NAG

Question 13

CPS 1 vs CPS 2
Site
Function
Source of Ammonia
Activator

Answer 13

CPS 1: Mitochondria, Urea Cycle, Free ammonia, NAG

CPS 2: Cytosol, pyrimidine synthesis, glutamine. PRPP

Question 14

ammonia in regards to renal and hepatic failure

Answer 14

renal: plasma level of urea increases
hepatic: plasma level of ammonia increases

Question 15

hereditary hyperammonia

1. carbamoyl phosphate synthethase 1
2. ornithine transcarbamaylose
3. arginino succinate synthethase
4. argininosuccinase
5. arginase

Answer 15

1. type 1 hyperammonia
2. type 2 hyper ammonia
3. citrullinuria
4. arginosuccinic academia
5. hyperargininemia

Question 16

what to do if hyper ammonia

Answer 16

ammonia cross BBB and alpha KG binds with it to form glutamate. This depletes a KG though so no TCA. or ammonia binds with glutamate to form glutamine so no glutamate which is neurotransmitter = convulsions because no GABA

Question 17

treatment of hyper ammonia

Answer 17

1. decrease protein, increase arginine
2. Na benzoate and phenylpyruvate
3. lactulose (cleaner)
4. enema
5. oral ornithine