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HUN 4221 EXAM 3 > Zinc (Part 2) > Flashcards

Zinc (Part 2) Flashcards

1
Q

What are the functions of zinc?

A

Catalytic, structural, regulatory

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2
Q

What is carbonic anhydrase?

A

First characterized zinc metalloenzyme

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3
Q

What does carbonic anhydrase do?

A

Interconverts carbon dioxide and bicarbonate to maintain acid-base balance in blood

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4
Q

What is the rxn of carbonic anhydrase?

A

CO2 +H20 -> H2CO3 (bicarbonate)

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5
Q

In carbonic anhydrase, zinc is coordinated by what?

A

3 histidine residues

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6
Q

What are examples of Zn catalytic functions?

A

Metalloenzymes:

  • Alcohol dehydrogenase
  • RNA polymerase
  • Alkaline phosphatase
  • carbonic anhydrase
  • carboxypeptidase A
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7
Q

What is carboxypeptidase?

A

A digestive enzyme produced by the pancreas

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8
Q

What does carboxypeptidase do?

A

Hydrolyzes peptide bonds

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9
Q

In carboxypeptidase, zinc is coordinated by what?

A

2 histidine and 1 glutamic acid residue

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10
Q

For carboxypeptidase, the R’ group can be any AA except?

A

Arg, Pro, Lys, and hydroxyproline

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11
Q

Why does the pancreas cause the body to lose a lot of zinc?

A

Because these digestive enzymes are secreted from the pancreas and a lot of them contain zinc.

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12
Q

What is an example of a structural zinc function?

A

Zn binding proteins

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13
Q

What is an example of a zinc binding protein?

A

Superoxide Dismutase 1

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14
Q

What is superoxide dismutase 1?

A

An antioxidant enzyme

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15
Q

What does Superoxide Dismutase 1 do?

A

It catalyzes the “dismutation” of superoxide, converting it to hydrogen peroxide

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16
Q

What is the role of Cu in superoxide dismutase 1?

A

Serves a catalytic role in electron transfer during dismutation rxn

17
Q

What is the role of Zn in superoxide dismutase 1?

A

Serves a structural role

18
Q

What is the most common DNA binding domain?

A

Zinc finger domain

19
Q

What are two different forms of mammalian zinc fingers?

A

C4 (4 Cysteine residues): Nuclear receptors and C2H2 (2 Cysteine and 2 Histidine residues) family

20
Q

What are examples of C4: Nuclear receptors?

A

Retinoic Acid Receptor (RAR) and Vitamin D receptor (VDR)

21
Q

Why do proteins have zinc finger domains?

A

It allows proteins to bind to DNA which may activate or inhibit the expression of genes.

22
Q

Zinc Status assessment

A

Plasma zinc <70micrograms/dL

23
Q

Why is Plasma Zn not a very good indicator?

A

Because it is affected by many factors such as stress, meal, time of the day, infection, medications

24
Q

What is an example of genetic zn deficiency?

A

AE (Acrodermatitis enteropathica)

25
Q

Who was the first person to document Zn deficiency?

A

Ananda Prasad

26
Q

When was Zn declared to be an essential nutrient in the U.S.?

A

1974

27
Q

Why is the skin on the cheeks affected by AE so much?

A

Because the skin on the cheeks is one of the fastest turning over pieces of skin on your face and have the highest zinc demand.

28
Q

Where is Zn deficiency prevalence high?

A

Africa, Asia

29
Q

Loss of life of children under the age of 5 is due to?

A

Vit. A def, Zn def, and Iron def.

30
Q

Vitamin A and Zn account for how much of childhood disability-adjusted-life-years

A

9%

31
Q

What is the RDA for Zn?

A

~10 mg

32
Q

Zn toxcity

A

Does not exist because body can excrete excess zinc

33
Q

Symptoms of toxicity can exist if

A

200 mg of zinc is taken

34
Q

What are the symptoms of Zn toxicity?

A

Nausea, vomiting, epigastric pain, abdominal cramps, bloody diarrhea

35
Q

Chronic ingestion of Zn (~40 mg/day) can cause what?

A

Cu def

36
Q

Penny case: why were his zn levels high?

A

Because he ingested post 1982 pennies which are mainly made of zinc and they were partially digested causing increase in zinc levels

HUN 4221 EXAM 3 (9 decks)

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