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Biochemistry Exam III material > Amino Acid Metabolism II > Flashcards

Amino Acid Metabolism II Flashcards

1
Q

Porphyrins are synthesized from ____ and _____

A

glycine and Succinyl CoA

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2
Q

The first step in the biosynthesis of porphyrins is the _____ of glycine and saucily CoA to form ______. this reaction is catalyzed by

A

Condensation, delta-aminolevulinate. delta-aminolevulinate synthase

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3
Q

The pathway of heme synthesis proceeds with ____ molecules of delta-aminolevulinate

A

8

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4
Q

ALA dehydratase catalyzes

A

8 delta-amino levulinate + 8H+ ——> 16 H2O + 4 Porphobilinogen

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5
Q

Porphobilinogen deaminase catalyzes

A

The condensation of 4 porphobilinogen head to tail to form linear tetrapyrrole

4 porphobilinogen ——> Linear tetrapyrrole

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6
Q

Uroporphyrinogen III synthase (and required cosynthase) catalyze

A

Linear tetrapyrrole —–> Uroporphyrinogen III

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7
Q

In the presence of uroporphyrinogen III synthase (without cosynthase) what reaction is catalyzed

A

linear terapyrrole ——> Uroporphyrinogen I

Uroporphyrinogen I is a nonphysiological symmetric isomer

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8
Q

Uroporphyrinogen decarboxylase catalyzes

A

Uroporphyrinogen III —–> Coproporphyringogen III

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9
Q

Acute intermittent porphyria acts is a defect on what enzyme

A

porphobilinogen deaminase

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10
Q

Congenital erythropoetic prophyria is a defect of what enzyme

A

Cosynthase

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11
Q

Coproporphyrinogen III undergoes a desaturation and conversion of two of the propionate side chains into vinyl groups to yield

A

protoporphyrin IX

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12
Q

the chelation of iron to protoporphrin IX produces

A

Heme

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13
Q

Heme is the prosthetic group of proteins such as

A 
myoglobin
hemoglobin
catalase
peroxidase
cytochrome C
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14
Q

The first step in the degradation of heme is

A

the cleavage of its alpha-methine bridge to form the green pigment Biliverdin (a linear tetrapyrrole)

Heme + 2O2 + NADPH——> CO + H2O + (NADP+) + Fe+ biliverdin

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15
Q

The central methine bridge of biliverdin is reduced by _________ to form what

A

biliverdin reductase to form bilirubin

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16
Q

Biliverdin reductase catalyzes

A

The reduction of the central methine bridge of biliverdin to form bilirubin

Biliverdin + NADPH + (H+) —-> Bilirubin + NADP +

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17
Q

bilirubin is extremely _____

A

lipophilic

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18
Q

Heme degradation products (_____ and _______)are responsible for the color of bruises

A

Biliverdin and bilirubin

19
Q

In heme degradation ______ is excreted

A

the porphin ring system

20
Q

UDP glucuronyl transferase does what

A

it makes bilirubin water soluble so it can be excreted in the urine

21
Q

Direct bilirubin

A

=conjugated bilirubin

22
Q

Indirect bilirubin

A

= unconjugated bilirubin

- is bound to albumin (albumin normally binds to bilirubin so it can be transferred to the liver)

23
Q

after ______ bilirubin goes into bile and goes out the common bile duct into the intestine

A

conjugation

24
Q

______ is a form of bilirubin that is made in the intestines, it then leaks back into the hepatic vein and is excreted in the urin

A

urobilinogen

25
Q

___________is a form of bilirubin that is made in the intestines and is excreted in the feces

A

Stercobilinogen

26
Q

_______ is not found in the liver of infants and can cause jaundice. Note that billirubin buildup in the brain can lead to

A

UDP glucuronyl transferase

Billirubin buildup in the brain can lead to mental disorders

27
Q

What is the amino acid precursor of spingosine

28
Q

What is the amino acid precursor of Histamine

29
Q

What is the amino acid precursor of Thyroxine (tetraiodothyronine)

30
Q

What is the amino acid precursor of epinephrine

31
Q

What is the amino acid precursor of serotonin

A

Tryptophan

32
Q

What is the amino acid precursor of Nicotinamide (unit of NAD+)

A

Tryptophan

33
Q

Nitric oxide synthase (NOS) catalyzes

A

Step 1: Arginine + (H+) + O2 + NADPH —–> H20 + (NADP+) + N-w- Hydroxy-arginine (BH4 is the cofactor needed by NOS)

Step 2: N-w-Hydroxy arginine + O2+ NADPH —–> (NADP+) + H2O + Citrulline + Nitric oxide (note that this is a free radical)

34
Q

What is type I phenol ketone urea (PKU)

A

defective nitric oxide synthase (NOS)

35
Q

What is Type II Phenol Ketone Urea (PKU)

A

No BH4 is present or is defective

36
Q

What is BH4 synthesized from

A

GTP (guanine triphosphate)

37
Q

What is the cofactor by Nitric oxide synthase (NOS) in the first step of nitric oxide synthesis

38
Q

Tyrosine forms DOPA which then converts into _____

39
Q

What are the 3 types of nitric oxide synthases (NOS)

A

nNOS- neuronal oxide synthase- makes nitric oxide as a signal molecule

iNOS- inducable nitric oxide synthase- produces nitric oxide as a killer compound in macrophages

eNOS- Endothelial nitric oxide synthase- acts a a vasodilator

40
Q

nitric oxide is a ______ lived molecule

41
Q

Nitric oxide is generated from

42
Q

Glutathione serves as an ______, reacting with ______ and ________

A

antioxidant, reacting with hydrogen peroxide and organic peroxides

43
Q

Glutathione is a ______ derived compound

44
Q

Components of Glutathione

A

it is a tripeptide composed of

  • gamma-Glutamate
  • Cystein
  • Glycine

Biochemistry Exam III material (13 decks)

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