Enzyme Inhibition and Regulation L3 Flashcards

1
Q

What is the basic premise on which enzyme inhibition is able to occur?

A
  • Able to affect specific enzymes
  • Sulfadrugs = inhibitors of folic acid synthesis mainly affecting bacteria
  • Methotrexate = inhibits dNTP production and hence DNA synthesis of malignant cells
  • Aspirin = inhibits prosta-gland synthesis, responsible mainly for arthritis
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2
Q

What are the two main broad groupings of enzyme?

A

Irreversible- covalent modification of the enzyme structure

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3
Q

Explain how Km and Vmax are affected for a competitive enzyme:

A

Vmax- same

Km- higher

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4
Q

Explain how Km and Vmax will be affected for non-competitive enzyme:

A

Km- the same

Vmax- lower

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5
Q

Explain how Km and Vmax will be affected for a uncompetitive enzyme:

A

Km- lower

Vmax- lower

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6
Q

Explain the properties of an allosteric enzyme:

A
  • Activity is controlled by effector molecules binding at distinct allosteric sites
  • Binding causes conformational change
  • Binding of first substrate induces high affinity substrate in the bound state as well as in many other contacting subunits, the other subunits will now bind with high affinity
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7
Q

Explain the properties of covalent modification:

A
  • reversible + rapid reactions

- e.g. phosphate, methyl, acetyl

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8
Q

Explain what is meant by the term proteolytic activation:

A

Very quick. Stored for a long time as zymogen then it is cleaved to produce the irreversible enzyme.

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9
Q

Explain what is meant by rate of enzyme synthesis/degradation:

A

Velocity of reaction dependant on [enzyme], this can be controlled by the rate at which it is synthesised or degraded.

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10
Q

Explain what is meant by compartmentalisation:

A

Anabolic and catabolic reactions are separated into different compartments within the cell.

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11
Q

Explain what is meant by the term regulation by control proteins:

A
  • Calmodulin = calcium - modulating protein
  • Mediates many calcium driven metabolic reactions
  • 4 binding sites for Ca2+
  • When the calcium concentration rises it then binds to the protein
  • Calmodulin is then activated and regulates other proteins
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