NBS2 Exam 1: Biochem "Other" AA metabolism

Question 1

What are the three prodcuts of arginine metabolism?

Answer 1

ornithine –>Petrescine, NO and Creatinine, glutamic acid, proline

Question 2

What enzyme converts arginine to petrucine?

Answer 2

ornithine decarboxylase converts ornithine to petrucine

Question 3

what inhibits ornithine decarboxylase

Answer 3

eflorcine.

Question 4

What does petrucine do?

Answer 4

It stabalizes DNA

Question 5

What does efloricine do?

Answer 5

it blocks ornithine carboxylase which destroys the tyranosomes of african sleeping sickness. It alo can help with hituisim (growth of hair on a females face)

Question 6

What does creatinine have to do with arginine?

Answer 6

You get creatinine from arginine which you use to measure GFR and kidney f(x)

Question 7

how do we produce serine?

Answer 7

we divert from glycolysis (from G3P) using transaminase

Question 8

serine can be broken down into what products?

Answer 8

glycine and pyruvate

Question 9

The conversion of serine to glycine involves the use of what intermediate and what enzyme

Answer 9

Serine hydroxy methyltransferase which uses Tetrahydrafolate, It gains one carbon in the rxn. This can then be used to make purines or thymdine.

Question 10

What happens in the breakdown of Glycine

Answer 10

It is broken down using glycine cleavage complex, which adds one carbons to THF, thus promoting nucelotide synthesis.

Question 11

what happens when glycine cleavage complex is broken?

Answer 11

Glycine accumulates and is an inhibitory neutotransmitter. Severe mental disability, death frequntly during infancy

Question 12

trace out serine metabolism

Answer 12

serine comes from G3P, it is broken down to glycine by serine hydroxy methyl transferase and creates a N5N10Folate in the process. Glycine can be broken down to oxaloacete (kidney stones) or is combusted to create more N5N10Folate leading to pyrimidine synthesis

Question 13

histidine metabilism is important why? (tell me about its metabolism)

Answer 13

Histidine is broken down into FIGLU. FIGLU can only be broken down further if folate is added. When folate is added, it adds a C in order to produce N5N10THF for 1 carbon metabolism and the synthetis of nucelic acids

Question 14

if you have increased FIGLU

Answer 14

your folate stores may have been depleted

Question 15

what AA break down and add to the folate pool?

Answer 15

Serine, glycine, histidine and tryptophan

Question 16

What is the folate trap?

Answer 16

The folate trap is a result of having the folate intermediates converted to methyl THF. Methyl THF is not in equilibrium with the rest of the methyl products. You need to use homocysteine and B12 to convert Methyl THF to THF. If you dont have B12, your folate stores will get trapped as methyl THF and you will lose your ability to make folate, thus inhibiting the ability to synthesize DNA. This leads to macrocytic anemia

Question 17

Why is B12 important in relation to folate

Answer 17

need B12 to convery Methyl THF to THF, which i used in 1 carbon metabolism to synthesize DNA

Question 18

B12 deficiency leads to

Answer 18

macrocytic anemia due to the deplation of the folate stores. You may also get homocysteneuria since homocysteine cannot be converted back to methionine int he remethylation pathway

Question 19

first step in the break down of methionine?

Answer 19

You add 3 ATP to methionine and get s-adenosyl methionine,

Question 20

s-adenosyl methionine is used in

Answer 20

Is a carbon donor and is important in the methylation of histones

Question 21

S adenosyl methioine (from methionine) is broken down into

Answer 21

s adenosyl homocysteine

Question 22

s adenosyl homocysteine is broken down into

Answer 22

homocysteine

Question 23

Homocysteine reacts with what amino acid?

Answer 23

serine

Question 24

when homocysteine reacts with serine, what enzyme do they use and what do they form?

Answer 24

cystathionine synthase converts homocysteine and serine into cystathione.

Question 25

What cofactor does cystathioine synthase use?

Answer 25

PLP

Question 26

what TCA cycle intermediate des methionine eventually break down into?

Answer 26

succinyl CoA

Question 27

cystathionine is broken down into what amino acid?`

Answer 27

cysteine

Question 28

deficinecy in cystathionine synthase will cause

Answer 28

homocysteneuria: the accumulation of homocysteine .

Question 29

the system that is mot important to consider in relation to homocysteneuria

Answer 29

the carviovascular system

Question 30

describe the remethylation pathway

Answer 30

homocysteine is converted back to methionine by putting a methyl group on it using B12 which ges its carbon from THF

Question 31

in homocysteneuria will see

Answer 31

increase homocysteneruia and methionine

Question 32

how do you treat homocysteneuria?

Answer 32

supplement with PLP/B6 and B12 and folic acid. Decrease methionine in diet.

Question 33

What is betaine used for?

Answer 33

Betaine boosts the remethylation pathway to make methionine from homocysteine by serving as a methyl group donor.

Question 34

what are the branched chain AA?

Answer 34

Valine, isoleucine and leucine `

Question 35

Explain MSUD

Answer 35

MSUD is the inability to break down branched chian alpha keto acids due to a defect in branched chain alpha amino dehydrogenase

Question 36

How are branch chain alpha keto acids broken down?

Answer 36

by branched chain alpha amino dehydrogenase

Question 37

how do you treat MSUD?

Answer 37

consume low levels of valine, leucine and isoleucine

Question 38

What is the cofactor used with branched chain alpha amino dehydrogenase

Answer 38

thiamine

Question 39

path of branched chain AA

Answer 39

Valine isolecuine and leucine –>brnahces chain AA –> propionyl –> Methylmalonyl coA –> succinyl CoA

Question 40

proprionic acidemia is due to what

Answer 40

the inability to break the propinionyl coA from branched chain AA into methyl malonyl CoA. Problem in Propionyl CoA. Or due to a B12 deficiency causing the enzyme to not work.

Question 41

what funnels into propionyl coA?

Answer 41

VOMIT: valine, odd chain aa, methionine, isoleucine, threonine

Question 42

what cofactors are used for propionyl coA carboxylase?

Answer 42

biotin, HCO3- and ATP

Question 43

multiple carboxylase defiiency

Answer 43

when you have decreased biotin: effect every carboxylase that uses biotin

Question 44

why is glycine increased in proprionic acidosis

Answer 44

metabolic chaos theory. proprionic acid will inhibit the glycine cleavage complex which combusts glycine for its 1-carbon metabolism power

Question 45

why is ammonia increased in proprionic acidemia

Answer 45

Proprionic acid inhibits CPS1 activity

Question 46

how do you treat proprionic acidosis

Answer 46

give carnitine to react with acetly CoA, the complex is excreted . Can also kill bactria in the gut to decrease the amount of proprionic acidin the gut.