Synthesis using amino acids

Question 1

what can be made from tyrosine

Answer 1

• dopamine: made in te brain, this mol is commonly associated with the pleasure system of the brain
• thyroxine: made in the thyroid, this is made on thyroglobulin
• melanin: made in the skin, skin pigment

Question 2

graves disease and thyroglobulin

Answer 2

-overproduction is associated with hyperthyroidism

Question 3

albinism and tyrosine

Answer 3

-patients with albinism lack the enzyme tyrosinase, leading to the lack of melanin pigments in the skin and eyes

Question 4

synthesis of what amino acids require one carbon tranfers?

-what examples of cofactors are required

Answer 4

• glycine, srine, cystein, and methionine

- these require cofactors such as biotin, THF, PLP, and SAM

Question 5

THF is derived from what?

-what enzyme is important in the synthesis of THF

Answer 5

• dietary folate

- dihydrofolate reductase makes THF from dihydrofolate

Question 6

THF works by

Answer 6

-carrying methyl groups on N5 and N10 of the methylpterin ring

Question 7

folate

Answer 7

• carry out essential methylation reactions
• found in green leafy veggies
• required in nucleic acid synth
• low levels of folate in pregnancy can lead to spina bifida

Question 8

what is the most common form of folate in the blood

Answer 8

• the methyl form
• it is formed in an irreversible reaction
• however, except for this form, most are readily interconvertible

Question 9

name of the easily convertible folate forms

Answer 9

-one-carbon pool

Question 10

what amino acids use THF and methylene THF

Answer 10

• THF is used to convert serine into glycine which in turn creates methylene THF
• this can also be ran in reverse to create serine and THF

Question 11

what is serine made from

Answer 11

-the glycolytic intermediate, 3-phosphoglycerate

Question 12

SAM

-nickname

Answer 12

• the methyl donor man
• made from methionine
• makes epi from norepi

Question 13

what is epi made from

Answer 13

dopamine

Question 14

creatine requires what for its synthesis

Answer 14

• SAM

- starts with arginine then guanidino acid which is made into creatine using SAM

Question 15

what does creatine do?

Answer 15

• this is the resevoir for ATP in muscle

- it is converted to phosphocreatine which is then used to make ATP from ADP

Question 16

what is methionine regenerated from? and how?

Answer 16

• from homocystein
• using the enzyme methionine synthase
• the enzyme uses methyl THF to methylate VB12 to make MeB12 which is then used to remethylate homocystein to make methionine

Question 17

what are the only two enzymes that require cofactors derived from VB12

Answer 17

• methylmalonyl mutase which creates succinyl Coa from BCAA’s
• methionin synthase to make methionine from homocystein

Question 18

what is analternative way that methionine can be regenrated?

Answer 18

-from homocystein using a derivative of choline called betaine

Question 19

what is homocystein used for if not for regenrating methionine?
-what are the two amino acids that this product are fundamentally derived from?

Answer 19

• cystein synthesis

- cystein is derived from methionine and serine

Question 20

what enzyme makes cystein from homocystein?

what does it require?

Answer 20

• cystathione synthetase

- requires PLP

Question 21

if methionine is deficient, what is also deficient?

Answer 21

-cystein

Question 22

what does the degradation of methionine form?

Answer 22

-alpha ketobutyrate

Question 23

taurine synthesis

-what is taurine?

Answer 23

• made from cystein
• organic acid that is also a major constituent of bile (conj with cholate)
• found in lower intestine and other tissues

Question 24

the folate trap

-what can be a consequence of this

Answer 24

• the methylene tetrahydrafolate reaction is essentially irreversible
• in order to convert methyl THF back to THF is through the VB 12 dependent methionine synthase reaction
• therefore a VB12 def can also cause a secondary def in folate

Question 25

homocystinuria

• how it is produced
• associated risks
• most common cause
• treatment
• problems with some treatment
• dietary causes

Answer 25

• in cells a build up of homocystein becomes
• associated with high risk of arterial disease, tall and thin people have problem with vision
• a defect in cystathione synthetase is the most common cause and may need to supplement cystein
• supplementation with VB6 (PLP)
• supplementation with choline and betaine may raise methionine levels which reforms homocystein
• supplementation with folate can reduce homocystein levels via methionine synthase