Amino acids and protein metabolism Flashcards
Function of transamination?
Turn AA into intermediate in TCA cycle
What catalyses process of transamination?
Amino transferase
Outline process of transamination?
1) Transfer amine group from amino acid to alpha-ketoacid
2) Makes alpha-ketoacid and amino acid
What is the universal acceptor of amine groups?
Alpha-ketoglutarate
What enzyme does alanine use?
What does it form?
Alanine aminotransferase (ALT)
Form pyruvate and glutamate
Explain process of deamination?
Glutamate converted back to alpha ketoglutarate
What enzyme converts glutamate ack to alpha-ketoglutamate?
Glutamate dehydrogenase
What does process deamination produce?
Ammonium- removed urea cycle
What cycle do aa enter?
TCA cycle
How much albumin is produced/day?
9-12g
How is albumin returned to liver?
Collected by lymphatics
Returned via thoracic duct
Functions of albumin? (4)
1) Binding and transport
2) Maintenance colloid osmotic pressure
3) Free radicals neutralisation
4) Anticoagulant effects
What is extrinsic pathway activated by?
Factor VII coming into contact with tissue factor
Where are fibrinogen, prothrombin, IV,V,VI,VII PRODUCED?
Liver
Can proteins be stored?
No
How are proteins degraded? (2)
1) Proteasome- ubiquitin dependent
2) Lysosomal
Explain process of proteasome degradation?
1) Ubiquitin activated by E1 enzyme in ATP-dependent reaction
2) Activated ubiquitin conjugated to specific ubiquitin-conjugating enzyme (E2)
3) This complex binds to ubiquitin ligase (E3)
4) Ubiquitin-ligase complex binds to a specific target protein resulting in polyubiquitination
5) Polyubiquitinated protein identified and directed to proteasome for degradation
6) Recycle Ub and amino acids for future use
What 3 enzymes involved in proteosome degradation?
E1 – ubiquitin-activating enzyme
E2 – ubiquitin-conjugating enzyme
E3 – ubiquitin-protein ligase
How does lysosomal degradation work?
Non selective
Digest protein, carbs, fats
Proteolytic enzymes
How does lysosomal degradation work?
Non selective
Digest protein, carbs, fats
Proteolytic enzymes
What occurs when dietary protein enters stomach, SI and enterocytes?
