Protein and AA metabolism Flashcards
What three things supply the AA pool?
- Protein turnover
- Digested food
- De novo synthesis
What three things deplete the AA pool?
- Production of body proteins
- synthesis of nitrogen containing compounds
- Degradation of **Essential amino acids
What is proteolysis?
degradation of proteins for reabsorption
How does an exopeptidase work?
Attacks the C and N-terminus (ends)
How does an endopeptidase work?
attacks within the protein at a specific site (digests internal peptide bonds.
Define lysosomal/autophagy
non-selective intracellular proteolytic control
- macroautophagy
- microautophagy
- chaperone-mediated autophagy (CMA)
Define Proteasomal degredation
large proteasome cytoplasmic complexes that cleave polyubiquinated proteins-> ubiquitin pathway
- selective pathway
- death tag
What is trypsinogen activated by?
enterokinase
How are proteolytic enzymes secreted?
They are secreted as needed and as inactive zymogens, which are activated by proteolytic cleavage
What are the 2 ketogenic AAs
Leu
Lys
What are the 5 ketogenic and gucogenic AAs
Phe Ile Tyr Thr Trp
What are the 13 glucogenic AAs
Val , His, Arg, Asn, Gln,
Met, Ala, Asp, Glu
Gly, Pro, Ser, Cys
What are ketogenic AAs degrated to?
Acetyl CoA or acetoacetate -> precursors for alpha ketoacids, ketone bodies, and fatty acids
What are glucogenic AAs degraded to?
Pyruvate or TCA cycle intermediates
-OAA, alpha ketogluterate,
Succinyl CoA, fumarate
(precursors for glucose synthesis)
Essential AAs
PVT TIM HALL
What AAs are degraded to alpha-ketogluterate?
Gln, His, Arg, Pro, Glu
What causes homocystinuria
defective enzume cystathionine beta-synthase
or deficiencies of b6, b12,or folic acid
homocystine cannot be converted to cystathionine
*eye, skeletal, CNS, Vascular
What are the branched chain amino acids
Met, Thr, Val, Ile, Leu –> succinyl CoA or Acetyl CoA
What does the body use for fuel during fasting and prolonged exercise?
Branched Chain AAs
What is maple syrup urine disease?
deficient branched chain alpha-keto acid dehydrogenase complex (BCKD) –> LEADS TO BRANCHED CHAIN KETOACIDURIA
-treat with synthetic diet limiting Val Leu Ile
What is Leu degraded to
Acetyl CoA
What is the end product of Phe metabolism
fumarate
What is the end product of Asn metabolism
Oxaloacetate
What is the cause of phenylketoneuria
Symptoms and treatment
PKU is caused by defects in the activity of phenylalanine hydroxylase (PAH)
