Enzyme Quetsions Flashcards
(12 cards)
What is the definition of Km
Km is equal to the substrate concentration to reach 1/2 of Vmax
It is an indicator of the enzymes affinity to its substrate
A high Km indicated a lower affinity, as it means that a larger substrate concentration is required to reach the maximum rate of reaction. And a low Km indicated a high affinity as a low substrate concentration is needed to reach the maximum rate of reaction
What does the turnover number of an enzyme indicate?
A rate constant - Kcat
Indicates how many MOLECULES of substrate can be converted by ONE MOLECULE of enzyme per time unit
Usually seconds or minutes
Kcat = Vmax / Total enzyme concentration
Is there an upper limit for the turnover number of an enzyme?
ZZ
How does the specific activity of an enzyme change when the concentration of enzyme in a reaction is varied
It does not vary/ it is not affected by a change in the concentration of enzyme in a reaction
As it already takes into account the total enzyme concentration
How does the pH of a reaction affect the rate of an enzyme reaction
It is dependent on the type of enzyme and the conditions it works best at.
It will increase until its optimum pH, then it will begin to stop and not react anymore
Some enzymes are not affect by large changes to pH whereas others are very sensitive
Will an enzyme isolated from a thermophillic ( living at high temperature) organism work at room temperature
It may work, but at a very very slow rate or it will not work at all
It is unlikely that an enzyme from a thermophillic organism will work efficiently at room temperature
How is Vmax affected, if the concentration of the enzyme in a reaction is increased
Vmax will also increase
As Vmax represents the maximum rate of reaction - if enzyme conecjration increases whilst substrate concentration stays the same. The reaction will happen more rapidly than with less enzyme concentration but same substrate concentration.
Will an enzyme isolated in a psychrophillic (cold loving) organism work at room temperature
It is unlikely but not impossible that an enzyme from a psycrophillic organism will work efficiently at room temperature
How does an enzyme affect the equilibrium of the reaction it is involved in
Enzymes DO NOT affect the direction or place of equilibrium.
They only affect the rate of reaction at which the reaction occurs.
How is Km affected, if you increase the concentration of the enzyme in a reaction
As Km works independenly of enzyme concentration and so will not be affected but a change in the concentration
It relates to the AFFINITY of an enzyme to its substrate
Varies with substrate concentration.
What does Vmax tell you about an enzyme
Vmax will inform you how quickly an enzyme works at a substrate concentration - extremely HIGH substrate concentration
What does Vmax/Km tell you about an enzyme
It is an enzyme parameter that tells us about how the enzyme behaves at EXTREMELY LOW substrate concentrations
It is a measurement of how well an enzyme concerts a substrate Iona product
