Protein and AA metabolism Flashcards Preview

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Flashcards in Protein and AA metabolism Deck (33):
1

What three things supply the AA pool?

-Protein turnover
-Digested food
-De novo synthesis

2

What three things deplete the AA pool?

-Production of body proteins
-synthesis of nitrogen containing compounds
-Degradation of **Essential amino acids

3

What is proteolysis?

degradation of proteins for reabsorption

4

How does an exopeptidase work?

Attacks the C and N-terminus (ends)

5

How does an endopeptidase work?

attacks within the protein at a specific site (digests internal peptide bonds.

6

Define lysosomal/autophagy

non-selective intracellular proteolytic control
-macroautophagy
-microautophagy
-chaperone-mediated autophagy (CMA)

7

Define Proteasomal degredation

large proteasome cytoplasmic complexes that cleave polyubiquinated proteins-> ubiquitin pathway
-selective pathway
-death tag

8

What is trypsinogen activated by?

enterokinase

9

How are proteolytic enzymes secreted?

They are secreted as needed and as inactive zymogens, which are activated by proteolytic cleavage

10

What are the 2 ketogenic AAs

Leu
Lys

11

What are the 5 ketogenic and gucogenic AAs

Phe
Ile
Tyr
Thr
Trp

12

What are the 13 glucogenic AAs

Val , His, Arg, Asn, Gln,
Met, Ala, Asp, Glu
Gly, Pro, Ser, Cys

13

What are ketogenic AAs degrated to?

Acetyl CoA or acetoacetate -> precursors for alpha ketoacids, ketone bodies, and fatty acids

14

What are glucogenic AAs degraded to?

Pyruvate or TCA cycle intermediates
-OAA, alpha ketogluterate,
Succinyl CoA, fumarate
(precursors for glucose synthesis)

15

Essential AAs

PVT TIM HALL

16

What AAs are degraded to alpha-ketogluterate?

Gln, His, Arg, Pro, Glu

17

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

18

What are the branched chain amino acids

Met, Thr, Val, Ile, Leu --> succinyl CoA or Acetyl CoA

19

What does the body use for fuel during fasting and prolonged exercise?

Branched Chain AAs

20

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

21

What is Leu degraded to

Acetyl CoA

22

What is the end product of Phe metabolism

fumarate

23

What is the end product of Asn metabolism

Oxaloacetate

24

What is the cause of phenylketoneuria
Symptoms and treatment

PKU is caused by defects in the activity of phenylalanine hydroxylase (PAH)

25

Instead of the production of tyrosine from phenylalanine, what accumulates in phenylketonuria

phe is converted to phenylpyruvate and then to phenyllactate (musty urine) and phenylacetate

26

What do triiodothyronine (T3) and Thyroxine (T4) monitor

thyroid disease

27

What enzyme is blocked in albinism

tyrosinase defect stops conversion of Tyr to melanin

28

What enzyme is affected in parkinsonism

dopa decarboxylase
-negatively affected by Carbidopa

29

What does thyroglobulin produce

T3 and T4

30

What do carbimazole and propylthiouracil treat

hyperthyroidism by reducing production of T3 and T4

31

Why is NH3 toxic, rather than NH4+

NH3 can traverse biological membranes

32

What does a defect in the ornithine transcarbamoylase cause

mitochondrial buildup of carbamoyl phosphate, which spills out into the cytoplasm

33

What can cause hyperammonemia

a defect of any of the 6 enzyes of the urea cycle (including NAG synthase)