Synthesis using amino acids Flashcards
what can be made from tyrosine
- 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
graves disease and thyroglobulin
-overproduction is associated with hyperthyroidism
albinism and tyrosine
-patients with albinism lack the enzyme tyrosinase, leading to the lack of melanin pigments in the skin and eyes
synthesis of what amino acids require one carbon tranfers?
-what examples of cofactors are required
- glycine, srine, cystein, and methionine
- these require cofactors such as biotin, THF, PLP, and SAM
THF is derived from what?
-what enzyme is important in the synthesis of THF
- dietary folate
- dihydrofolate reductase makes THF from dihydrofolate
THF works by
-carrying methyl groups on N5 and N10 of the methylpterin ring
folate
- 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
what is the most common form of folate in the blood
- the methyl form
- it is formed in an irreversible reaction
- however, except for this form, most are readily interconvertible
name of the easily convertible folate forms
-one-carbon pool
what amino acids use THF and methylene THF
- 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
what is serine made from
-the glycolytic intermediate, 3-phosphoglycerate
SAM
-nickname
- the methyl donor man
- made from methionine
- makes epi from norepi
what is epi made from
dopamine
creatine requires what for its synthesis
- SAM
- starts with arginine then guanidino acid which is made into creatine using SAM
what does creatine do?
- this is the resevoir for ATP in muscle
- it is converted to phosphocreatine which is then used to make ATP from ADP
what is methionine regenerated from? and how?
- 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
what are the only two enzymes that require cofactors derived from VB12
- methylmalonyl mutase which creates succinyl Coa from BCAA’s
- methionin synthase to make methionine from homocystein
what is analternative way that methionine can be regenrated?
-from homocystein using a derivative of choline called betaine
what is homocystein used for if not for regenrating methionine?
-what are the two amino acids that this product are fundamentally derived from?
- cystein synthesis
- cystein is derived from methionine and serine
what enzyme makes cystein from homocystein?
what does it require?
- cystathione synthetase
- requires PLP
if methionine is deficient, what is also deficient?
-cystein
what does the degradation of methionine form?
-alpha ketobutyrate
taurine synthesis
-what is taurine?
- made from cystein
- organic acid that is also a major constituent of bile (conj with cholate)
- found in lower intestine and other tissues
the folate trap
-what can be a consequence of this
- 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
homocystinuria
- how it is produced
- associated risks
- most common cause
- treatment
- problems with some treatment
- dietary causes
- 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
