Synthesis of amino acids Flashcards Preview

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Flashcards in Synthesis of amino acids Deck (10):

Describe the synthesis of amino acids from phenylalanine 

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What does epinephrine and norepinephrine break down into

VMA: vanillymandelic acid

Pheochromocytoma leads to increased VMA


What does dopamine break down into

HMA: homovanillic acid



Describe the synthesis of serotonin 

  • Serotonin is synthesized in the gut, platelets and CNS 
  • Synthesized from tryptophan 
  • Serotonin is metabolized to 5-HIAA by MAO


Describe the steps of tryptophan to serotonin 


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Describe carcinoid syndrome 

  • Tumor of serotonin producing cells in GIT (APUD cells)
  • Cutaneous flushing, sweating, diarrhea, bronchospasm 


Describe tetrahydrobiopterin

  • Reactions using THBP
    • Phenylalanine hydroxylase (converts Phe to Tyr)
    • Tyrosine hydroxylase (converts Tyr to DOPA)
    • Tryptophan hydroxylase (converts Trp to 5-hydroxy tryptophan)


Describe tetrahydrobiopterin deficiency 

  • Results in hyperphenylalaninemia and decreased synthesis of neurotransmitters 
    • Severe mental impairments and seizures 


Describe the steps in formation of thyroid hormone 

  • Trapping iodine in the thyroid cell
  • Iodination of the thyroglobulin protein 
  • Coupling of the iodinated Tyrosine side chains 
  • Release of thyroid hormone 
  • De-iodination of T4 to the active T3 form 

Example of post translational modification



Describe the function of thyroperoxidase

  • TPO fixes iodine to thyroglobulin 
  • Next TPO acts as a peroxidase 
    • Objective is to link two iodo-tyrosine side chains together