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amino acids Flashcards

1
Q

Gamma glutamyl cycle

A

to maximise the absorbance of amino acids from our diet . Happens in the SI and kidney.

glutathione gets cleaved by enzyme G glutamyltranspepidase allowing the glutamate to combine with the aa, leaving free glycine and cysteine
the glutamate and aa form g glutamyl AA.

G glutamyl aa, releases the aa and then forms 5 oxoproline by emnzymbe 5 oxoprolinase. then glutamate

glutamate then recombines with cyteine first to form g glutamyl cysteine. then lastly with glycine to reform glutathione

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2
Q

essential aa

A

phenylalanine
methione
tryptohan

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3
Q

how do we form seratonin and melatonin

A

tryptophan hydroxylase (BH4) gives us 5 hydroxytryptophan. then next step is decarboxylation to give us 5 hyrdroxytryptamine (seratonin) using cofacto b6

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4
Q

how do we form melatonin

A

start of with seratonin and you add an acetyl group using the enzyme seratonin n acetyl transferase giving you N acetyl seratoning/normelatonin. cofactor is acetyl coa. then you add a methyl group using the enzyme N-acetylseratonin o methyl transferase using cofactor SAM.

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5
Q

NAME THE COFACTORS OF TRYPTOPHAN DERIVED NEUTOTRANSMITTERS

A
  1. BH4
  2. B6
  3. ACETYL COA
  4. SAM
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6
Q

what are tryptophan and tyrosine derived neurotransmitters

A

tryp: seratonin and melatonin
tyr: catecholamines

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7
Q

how do we make catecholamines

A
  1. phenylalanine hydroxylase (BH4)- gives u tyrosine
  2. Tyrsoine hydroxylase-(BH4) gives u DOPA
  3. DOPA gets decarboxylated by aromatic amino acid decarboxylase to form dopamine
  4. Dopamine gets hydroxylated to form noradrenaline (using vIT C)
  5. noradenaline gets methylated to form adrenaline (SAM) (phenylethanolamine n metheyl transferase)
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8
Q

what is parkinosns and how to we treat

A

results from the death of the dopamine containing cells of substantia nigra region of midbrain. Early stage: movement related issues. Late stage: cognitive issues.

treat by L-dopa levodopa and dopamine agonists. L-dopa can cross the BBB so will increase levels of dopa. however you need to take levodopa with carbidopa which is an inhibitor of decarboxylase to prevent side effects.

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9
Q

melanin

A

skin , hair, iris

ubiquiotous pigement in nature
main- eumelanin
others- pheomelanin +neuromelanin

Production of melanin is stimulated by UVB-radiation
and it leads to a delayed development of a tan.
• The photochemical properties of melanin make it an

excellent photoprotectant. It absorbs harmful UV-
radiation and transforms the energy into harmless

heat through a process called “ultrafast internal
conversion”.

Tissues with melanin are the medulla and zona
reticularis of the adrenal gland, and in the brain the
pigment-bearing neurons within areas of the
brainstem, such as the substantia nigra.
• The melanin in the skin is produced by melanocytes, which are found in the basal layer of the epidermis.

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10
Q

deficiency of melanin

A

due to a defiency of the enzyme tyrosinase causes albininism

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11
Q

gltuathione

A

most abundant, water soluble thiol molecule in the cells . a powerful reducing agent. involved in the g glutamyl cycle . glutmate, cysteing and glycine

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12
Q

gltuathione and its jobs

A

most abundant, water soluble thiol molecule in the cells . a powerful reducing agent. involved in the g glutamyl cycle . glutmate, cysteine and glycine

  1. make leukotrienes
  2. make pheomelanin
  3. powerful antioxidant
  4. detoxification of xenobiotics
  5. important in RBC metabolism as it detoxifies harmful peroxides which would otherwise destroy the RBC. requries NADPH to get it back to reduced state
  6. transports aa/glutamyl cycle
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13
Q

different mechanisms to make amino acids

A
  1. reductive amination-glutamate
  2. amination -glutamine
  3. transamination /alanine +aspartate
  4. transamidation- makes aspargine
  5. cyclisation _proline from glutamate
  6. hydroxylation -makes tyrosine from phenylalanine
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14
Q

draw an example of transamidation

A

Aspartats+glutamine= glutamtae and aspargine

enzyme:aspargine sythetase (mg2+)

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15
Q

draw cyclisation and name the intermediate products

A
  1. glutamate
  2. glutamte g semialdehyde
  3. pyrrolidine 5 carboxylate
  4. proline
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16
Q

how do we make cysteine?

A

start from methione which forms SAM (methione adensyl transferase)

SAM-S form adenosylhomocysteine(methyl transferase)

S-adenosylhcysteine forms homoscyteine

homocysteine+ serine—(cystathione synthase)-cystthione
cystahtione lyase- cysteine + a keto butyrate

17
Q

cystathione sythanse

cystathion lyase

A

enzymopathies can occur

  1. homocysteinuria -associated with mental retardation although many people are normla
  2. excrete cystahione in urie but no other unwanted effects
18
Q

selenium cystein

A

where the S of cysteine is replaced by selenium, is a cofactor for enzymes like glutathione peroxidase and deiodinase

19
Q

how do we make serine?

A

by the glycolysis intermediate 3 phosphoglycerate.

  1. 3 P glycerate gets oxidised to 3 P hydroxy pyruvate
  2. with glutamate getting converted to a ketoglutarate we form 3 phospho serine
  3. 3 phosphoserine gets turned into serine with the enzyme phosphoserine phosphatase
20
Q

form which glycoloytic intermediate do we use to make a particular aa?

A

serine

21
Q

which synthesis of aa starts out with methione

A

cysteine

22
Q

how do we make serine

A

its a reversible reaction from glycine!

23
Q

what are the 2 ways we make glycine

A

Convert serine.
enzyme: SHMT (serine hydroxy methyl transferase)
convert THF TO n5n10 methylene THF v important

other way is form choline

24
Q

list the amino acids that our bodies make

A 
proline
tyrosine
serine
glycine
cysteine
aspargine
glutamine
glutamate
aspartae
alanine
25
Q

biologiclaly active compounds from aa

A
  1. serine
    - proteins
    - phospholipids
    - sphingosine +sphingolipids
  2. Arginine
    - urea
    - ornithine
    - no
    - spermine and spermidine

Polyamine biosynthesis which involves ornithine to putrsecine to spermidine to spermine

tryptophan-seratonin and melatonin
tyrosine-catecholamines,melanin

GLUTATHIONE

AA (2 decks)

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