Enzymes Flashcards

1
Q

What is the michaelis-menten equation?

A

V = (Vmax * [s]) / (Km + [s])

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is Km?

A

the michaelis-menten constant

  • the substrate concentration at which the reaction rate is half of Vmax
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the unit of measure for enzyme reaction rates?

A

μmol/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is specific activity?

A
  • amount of product formed by an enzyme in a given amount of time under given conditions per milligram total protein
  • more simply it is the “ratio of enzyme to non-enzyme molecules”

example:

a flask with 100 units protein and 10 units enzyme has lower spec. activity than one with 50 units protein and 6 units enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the types of reversible enzyme inhibitors?

A
  • competitive
  • non-competitive
  • un-competitive
  • apparent competitive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does a competitive inhibitor do?

How does it work when substrate is abundant?

How does it affect kinetics?

A
  • a competitive inhibitor is a substrate analogue which binds to the active site
  • does not inhibit in substrate excess

Vmax: no effect

Km: increases

ex: methanol to alcohol dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does a non-competitive inhibitor do to an enzyme?

A
  • binds away from the active site and disables enzyme
    by changing the active site

Vmax: lower

Km: unchanged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does an un-competitive inhibitor work?

How does it affect kinetics?

A
  • binds only to the enzyme-substrate complex

Vmax: decreases

Km: also decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does apparent competitive inhibition work?

How does it affect kinetics?

A
  • the inhibitor binds to an allosteric binding site and induces a conformational change in the enzyme
  • its kinetics are similar to that of competitive inhibition:

Vmax: unchanged

Km: increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does an allosteric activator effect an enzyme?

A
  • binds to allosteric site and induces conformotional change which:

increases Vmax

decreases Km

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How do inducers and repressors effect enyzme activity?

A

inducers: stimulate enyzme synthesis

repressors: inhibit enzyme synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly