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BGM1002-Biochemistry > BGM1002/L07 Enzymes III > Flashcards

BGM1002/L07 Enzymes III Flashcards

1
Q

Give the 5 types of enzyme inhibition.

A

Irreversible
Reversible
-Competitive
-Non-competitive
-Uncompetitive

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2
Q

What is Kcat?

A

Turnover number

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3
Q

How do irreversible inhibitors usually bind?

A

Covalent bonding

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4
Q

Which amino acids do irreversible inhibitors often bind to (2)?

A

Serine or Cystine

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5
Q

What does Sarin nerve gas bind to?

A

Serine residue in Acetylcholinesterase enzyme

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6
Q

What does Aspirin bind to?

A

Prostaglandin H2 synthase at S530

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7
Q

What does Penecillin bind to?

A

Serine in PBPs

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8
Q

Name 3 examples of enzyme inhibitor drugs.

A

Aspirin
Penecillin
Sulbactam
Allopurinol
AZT (Zidovudane)
Elflornathine
Sarin
5-fluorouracil
Exemestane

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9
Q

By what mechanism do competitive inhibitors work?

A

Competition with substrate for access to active site

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10
Q

How can competitive inhibitors be overcome?

A

Increasing [S] until it out-competes the inhibitor

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11
Q

How do competitive inhibitors affect Km and Vmax at fixed [S]?

A

Km increases
Vmax remains constant

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12
Q

What drug inhibits dihydrofolate reductase?

A

Methotrexate

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13
Q

How much more strongly do competitive inhibitors bind to enzymes than natural substrates?

A

1,000 - 1,000,000x

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14
Q

What does the competitive inhibitor acarbose bind?

A

Alpha-glucosidases

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15
Q

What do statins inhibit?

A

HMG-coA reductase

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16
Q

How do non-competitive inhibitors affect Km and Vmax?

A

Km unaltered
Vmax decreased

17
Q

Where do non-competitive inhibitors bind?

A

Away from enzyme active site

18
Q

What’s the difference between non-competitive and uncompetitive inhibitors?

A

Non-competitive bind to the enzyme and ES complex
Uncompetitive bind only to the ES complex

19
Q

How do uncompetitive inhibitors affect Km and Vmax?

A

Km decreases
Vmax decreases

20
Q

What changes in the physical and chemical environments can affect enzyme activity? (5)

A

Temperature
pH
Salts
Other chemicals
Molecular crowding

21
Q

How does pH affect enzyme activity?

A

Protonation/deprotonation of ionisable side chains

22
Q

How does temperature affect enzyme activity? (3)

A

Changes to diffusion rate
Flexibility of active site
Stability of enzyme

23
Q

How does molecular crowding affect enzyme activity?

A

Molecules can become spatially trapped and decrease diffusion rate

BGM1002-Biochemistry (29 decks)

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