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Dems Unit 02 - 02 > Protein Biochem - eisenmesser > Flashcards

Protein Biochem - eisenmesser Flashcards

1
Q

Ketogenic aa

A

Leu

Lys

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2
Q

Both ketogenic and glucogenic aa

A

Phe
Tyr
Iso
Trp

“Pee TIP”

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3
Q

Post translational mod of which two proteins strengthen and modify Collagen? Why do we care?

A

4-hydroxyproline (Hyp)
- Interstrand H bonding

5-hydroxylysine (Hyl)

  • interstrand X-links between Lys & Hyl
  • forms covalent interstand X- links

*collagen is the most abundant protein in body

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4
Q

Both Prolyl hydoxylase and Lysel hydroxylase require what?

A

Ascorbate (VIt C) in order to convert Pro to Hyp and Lys to Hyl

(without it

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5
Q

Sx of scurvy

A

Reduced strength of collagen fibrils

Reduced vascular endothelium

→ swollen gums, bruising, anemia

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6
Q

gamma-carboxyglutamate (Gla) fxn

  • what does it do
  • what is it dependent on?
A

transmembrane prot that converts Glu to Gla by chelating Ca2+

Vit K dependent
Used by Prothrombin to target membranes

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7
Q

Which one degrades endogenous protein, and which extracellular prot?
Ubiquination, lysosomal degradation

A

Ubiquination: endogenous
- targets enzymes (E1-E3) to proteins (lysine) using ATP and direct them into proteosome

Lysosome: extracellular
- taken in by endocytosis to mix with digestive enzymes

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8
Q

Enzymatic degradation proteins in:

  • Stomach
  • intestine
A

Stomach
- Pepsin (peppy chief)

Intestine

  • Trypsin
  • Chymotrypsin
  • Carboxypeptidase-A + B
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9
Q

How are these enzymes activated from zymogens

Stomach
- Pepsin (peppy chief)

Intestine

  • Trypsin
  • Chymotrypsin
  • Carboxypeptidase-A
  • Carboxypeptidase-B
A

Stomach
- Pepsinogen → Pepsin (peppy chief) (via HCl)

Intestine

  • Trypsin (via enteropeptidase)
  • Chymotrypsin (via trypsin)
  • Carboxypeptidase-A + B (via enteropeptidase)

*note that Trypsin can activate all of the E in intestine

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10
Q

Which one of these are aspartic proteases, serine proteases, and metallocarboxypeptidases

  • Carboxypeptidase-A+B
  • Trypsin
  • Chymotrypsin
  • Pepsin (peppy chief)
A

Aspartic: (hydrolyzes N term)
- pepsin

Serine: (hydrolyzes C term)
- Trypsin + chymotrypsin

Metallocarboxypeptidases
(hydrolyzes C term)
- Carboxypeptidase A+B

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11
Q

Aminotransferases catalyze what?
Major goal?
Where?

A

Rxn of an a-keto acid and an amino acid to another a-keto acid and amino acid

  • Reversible Keq=1
  • Major goal: make Asp, NH3 for Urea cycle
  • Mostly in cytosol (liver, kidney, intestine, muscle)
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12
Q

Transamination feeds what?

A

The urea cycle

- Major goal: make Asp, NH3 for Urea cycle

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13
Q

What does PLP form with the aminotransferase?

A

Forms “Schiff base” (a covalent linkage) with the aminotransferase,

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14
Q

Progressive hyperammonemia can cause

A

cerebral edema, coma, and death

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15
Q

Alanine + a-ketoglutarate → ?

aspartate + a-ketoglutarate → ?

A

ALT: pyruvate + glutamate

AST: oxaloacetate + glutamate

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16
Q

When you see ORNT1, think:

A

Ornithine INto mitochondria matrix

Citrulline OUT into cytosol

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17
Q

Control point for protein catabolism

A
  1. Directionality of ALT + AST regulated by products + substrates
  2. Carbamoyl phosphate synthetase I
    - required activator: N-acetylglutamate
  3. Glutamate dehydrogenase
    - regulates NH3 transport
    - depends on [ ] of Glu, a-ketoglut, NH3
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18
Q

Ammonia is toxic, so how do you transfer it from peripheral tissues to kidneys and liver?

A

Glutamine is used to hold 2 Ns

Glutamate (1 N) + NH3 + ATP + (Gln synthetase) → glutamine (2 N)

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19
Q

What is produced for the transport of ammonia in:
Peripheral tissue:
Muscle:
Liver:

A

Peripheral tissue: Gln
Muscle: Ala
Liver: Urea

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20
Q

What role does the kidney play in the transport of ammonia?

A

Removes Urea

Removes Ammonia from Glutamate

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21
Q

What is significant about Glu dehydrogenase?

A

It is involved in the transport of ammonia

  1. converts Glutamate → a-ketoglutarate
    - provides free NH3 for Urea cycle
    - pee out NH3 (kidney)
  2. Converts a-ketoglutarate + NH3 → Glutamate
    - Glutamate can be converted to Ala for transport from muscle to liver
    - Glutamaet can be converted to Glutamine for transport from periph tissue to liver
22
Q

Activator vs inactivator of glutamate dehydrogenase

  • ATP
  • ADP
  • GTP
  • GDP
A

Inactivator
- ATP + GTP

Activator
- ADP + GDP

(mutation in ATP/GTP binding site → hyperinsulinism-hyperammonemia syndrome: cant shut off NH3 maker)

23
Q

NO is derived from what?

A

Arginine via NO synthase

Arginine + NO synthase → Citrulline + NO

NO is a NT

24
Q

Aspartate transamination yields _______. It can be converted to _____ in the krebs cycle TCA.

A

oxaloacetate, fumarate

aspartate and asparagine yields oxaloacetate

25
Q

Asparagine yields ______ after hydrolysis catalyzed by the enzyme _____.

A

Asparagine → aspartate via asparaginase

aspartate can be converted to oxaloacetate just like asparagine

26
Q

MSUD - what Enz is affected? Deficiency or lack of? This leads to build up of?

A

Deficiency of BCKDH
(branched chain a-keto acid dehydrogenase)

Build up of branched chain aa Val, Ile, Leu

27
Q

Rank most active to less active
Tyrosine
T4
T3

A

T3 > Tyrosine > T4

T4 is made from tyrosine. T4 is a prohormone, so not very active

28
Q

Order that they are made
Tyrosine
T4
T3

A

Tyrosine → T4 → T3

29
Q

How is T3 and T4 made?

A

Thyroglobulin (TG) binds to I2 and gets iodinated. Then it undergoes protealysis to T3, T4

Thyroxin binding protein (TBP) carries it to blood

30
Q

TSH

A 
Stimulates Iodide (I-) uptake
Stimulates release of T4, T3
31
Q

Thyroid peroxidase

A

Oxidizes Iodide (I-) to (I2)

32
Q

Thyroglobulin (TG)

A

Contains Tyr residues iodinated to form T4, T3

33
Q

Thyroxin binding globulin (TBG)

A

Transports T4, T3

34
Q

How does lead lead to anemia?

A

Can replace Zn in ALA dehydratase
- prevent production of porphobilinogen

Can replace Fe2+ in ferrochelatase
- prevents heme production

35
Q

What enzyme is typically low in premature infants leading to jaundice babies? What other defects also involve this enzyme?

A

Bilirubin glucuronyl transferase

  • use flourescent light to convert bilirubin to more polar products, allowing removal
  • remember that this Enz allows unconj bilirubin to be converted to bilirubin, which will eventually become conj bili
  1. Crigler-Naijar syndrome
  2. Gilbert syndrome
36
Q

Which is essential, which is non essential? Methionine, cysteine.

A

Methionine is essential
- cysteine can be made from Met (non essential)

*noet: cysteine can form disulfide crosslinks with other cysteines to form CYSTINE.

37
Q

1st step of Met degradation

A

Methionine → SAM via
SAM synthase + ATP

SAM has an activated sulfur
SAM is also known as adoMet

38
Q

How does methionine degrade and form cysteine?

A

Met + Ser = Cys

Met → SAM → SAH → Homocysteine (+Ser) → Cystathionine → Cysteine

(these rxns involve addn of ATP, demethylation, and removal of adenosine)

39
Q

How do you regenerate Methionine

A

Need TWO coenzymes:

  1. THF
  2. Vit B12
  • methyl group is transferred from THF to B12 to homocysteine
40
Q

Which Vit are probably deficient if you have a build up of homocysteine?

A

B6 and B12

41
Q

How is cysteine synth achieved from Homocysteine and serine?

A

Via cystathionine B-synthase (CBS) + PLP

PLP is a derivative of Vit B6
- it is also needed to convert cystathionine to cysteine.

42
Q

Hyperhomocysteinemia levels

- tx

A

(Possible MTHFR enz defective and cant convert Homocysteine to methionine)

Low levels folate
Low levels B6, B12

  • cysteine is now an essential vit
    tx: folate, B6, B12
43
Q

Homocystinuria defect

- tx

A

defect in cystathionine B Synthase (CBS)

  • retardation, osteoporosis, vascular disease
  • cysteine is now essential (just like hyperhomo)

Tx: Vit B6, to force CBS activity

44
Q

Cysteinuria defect

- tx

A

defective transporter of cysteine (COAL)
- crystalization in kidneys (stones)

Tx: acetazolamide - makes cysteine more soluble

45
Q

Is homocysteine good?

A

No! IS bad!

  1. Vascular disease
  2. Impaired wound healing
  3. Correlated to cancer (cervical)
46
Q

SAM actions

A
  1. Methylation via SAM dependent enzymes
  2. Epigenetics (host defense)
  3. Cancer (meth/demeth)
  4. High levels of Met and SAM critical in maternal diet
  5. treat depression
47
Q

THF is produced from Vit B9 (Folic acid) by what enzyme?

What drug blocks this enzyme?

A 
Dihydrofolate reductase (DHER)
- blocked by methotrexate

Methotrexate basically prevents production of THF

48
Q

Why is Glutathione (GSH) important?

A
  1. Thiol (glutaTHIO) acts as a redox buffer to keep proteins in reduced form and regulate activity
  2. cofactor for other enzymes
  3. Protection against ROS (reduct H2O2)
49
Q

Glutathione (GSH) is it active in unfolded (reduced) state or folded state?

A

Active in folded state

- disulfide bonds are cross linked and ready fo action

50
Q

Example of how GSH acts as a redox buffer to keep proteins in reduced form and regulate activity

A

Keeps Fe2+ in ferrous state, capable of binding O2.

Fe3+ cannot bind O2

51
Q

Why is Trp such an important aa?

A
  • Trp can be metabolized to Pyruvate or acetyl-CoA
  • Trp (with BH4 cofactor) make:
    1. Serotonin
    2. Melatonin
    3. Niacin (critical cofactor for NAD)
52
Q

Why are MAO inhibitors so helpful?

A

They block deamination like cray. Prevent the breakdown of DA.

Dems Unit 02 - 02 (20 decks)

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