Enzyme Kinetics Flashcards
Factors (4) that affect enzyme kinetics
Temperature, pH, presence of activators/inhibitors, substrate
What effect does pH have on a protein?
pH affects protonation/deprotonation of an active site and can lead to denaturation in extremes.
What is the optimal temperature for enzyme activity?
37 degrees Celsius
As temperature increases by 10 degree increments toward 37 degrees Celsius, the enzyme’s activity increases by ___.
2x
Why is transition state energy important for enzyme-substrate binding?
Transition state energy is used for the enzyme to complete its rxn
Why do enzymes have no effect on the Keq ([P]/[S])?
Enzymes are released at the end of the reaction. Enzymes “cancel out” at the end of the reaction.
In a zero order reaction, the substrate is ____ so the reaction is dependent on concentration of___.
saturated, enzyme
First order reactions are dependent on ____ concentration.
substrate
Second order reactions are often treated as ___-___ ___ reactions because the amount of one of the ____ is kept very high.
pseudo-first order, substrates
E.g. think of water being in high concentration. We ignore water when it is one of the substrates because the reaction becomes independent of water.
Which step in the Michaelis-Mentin model is the rate limiting step?
K2
Write out the Michaelis Menten Equation.
v= [vmax {S}]/[Km + {S}]
The Km value equals ___ in first order kinetics.
1/2 vmax
If you want to understand the enzyme activity, run the experiment at ___ ___ reaction conditions. If you want to understand the substrate activity, run the experiment at ___ ___ reaction conditions.
zero order, first order
What does the Km value mirror?
The substrate concentration.
The amount of substrate that yields product per molecule of enzyme available. Also called the turnover rate.
Kcat
Enzymes with a high K2/Km (or Kcat/Km) value are reaching ____ ____.
Kinetic perfection
Kcat/Km is also called the ___ ___.
Specificity constant
When comparing two enzymes, saturate with [S] and choose the enzyme with the highest what?
Specificity constant
Explanation: means that the enzyme binds to the substrate with high affinity and has a high turnover rate.
What does having an easily diffusible product (like carbon dioxide) do to the specificity constant?
Increases the value
What types of reactions form a ternary complex?
single displacement and random
How do single displacement reactions appear on a Lineweaver-Burk graph?
The lines intersect at vmax
How do double displacement reactions appear on a Lineweaver-Burk graph?
The lines are parallel
Double displacement reactions are also called ___ ___ reactions.
Ping Pong
What are the three types of reversible enzyme inhibitors?
Competitive, noncompetitive, uncompetitive
