Chapter 8- Enzymes Flashcards
Life can be defined as what?
- dynamic
- coordinated network of chemical reactions
- avoiding equilibrium
How do we coordinate chemical reactions? And why are they usually not coordinated?
- we want them coordinated which is done by enzymes
- they can’t because they have different kinetics
what brings about coordination in individual reactions?
catalysis and the catalysts are enzymes
How are enzymes catalysts?
adjust there RATE of every reaction
Do the rates of catalysis differ? And why is this important?
Yes, completely. From seconds to billions of years. This refers to the reason of coordination and how it becomes completely coherent.
How do catalysts work?
- decrease activation energy (Ea)
- change kinetics but not the thermodynamics of a reaction
What do catalysts take time?
transition state
If DELTA G is positive what can be said about the the reaction? And what about if DELTA G is negative?
-: favorable
+: not favorable
If DELTA G is at 0 what can be said about the reaction?
at equilibrium
Enzymes have two part active site that accomplishes what?
substrate binding and catalysis
What are the two things that enzymes do?
- bind substrate (enzyme- substrate complex)
- change substrate into product and dissociate
What do enzymes have in relation to there substrates?
specificity (unique and wide open)
Substrate binding is usually what kind of model? What is the other model that it sometimes can be?
- induced fit
- lock and key
Enzymes are classified how?
proteins
Michaelis Menten kinetics characterizes a majority of enzymes quantifying what?
- substrate affinity (KM)
- catalysis (V-max)
For the Michaelis Menten curve what is the x axis and what is the y axis?
x: substate concentration
y: reaction velocity
For a simple saturated curve what can be explained about it?
it asymptotically reaches max velocity
The rate for enzymes in MM is dependent on what?
concentration
How many experiments do you have to do for enzyme kinetics?
multiple more than 4
What is the slope in Enzyme kinetics?
velocity
Why does the enzyme go at different rates?
concentration varies of 1 substrate
Why is MM kinetics important?
Help understand how enzymes work
What is KM?
substrate concentration yielding a velocity of Vmax/2
The KM value for an enzyme depends on the particular substrate and on environmental conditions such as pH, temperature,
and ionic strength.
What does the KM value depend on?
- on the particular substrate
- on environmental conditions
- pH
- temperature
- ionic strength
Big VMAX is…..
high rate at better which it catalyzes
Big KM is….
worse substrate affinity
Enzymes that have what have non MM kinetics?
cooperativity
Sigmodial curve means
cooperative enzyme and Non MM kinetics
Standard inhibition means what?
MM behaving
What are some types of standard inhibition?
competitive, non competitive, and uncompetitive
What can regulate enzymes?
Standard inhibition or MM behaving
What is a non competitive inhibitor?
affects the substrates ability to catalyze but not to bind
What is an uncompetitive inhibitor?
affects both the binding and catalysis
In competitive inhibition what is to be said about KM and Vmax?
KM change
Vmax same
In non competitive inhibition what is to be said about KM and Vmax?
Vmax change
KM same
In uncompetitive inhibition what is to be said about KM and Vmax?
Vmax change
KM change
What makes good competitive inhibitors?
transition state analogs
How do enzymes work?
decrease activation energy make the transition state with lower energy
Can you make a transition state? If so why not?
You cannot make a transition because unless an analog (or similar compound) is used
When is standard inhibition most commonly used in a pharmacology application?
Penicillin
Enzymes can use what and can be classified how?
cofactors
coenzymes
cosubstrates
can be classified by the type of reaction they catalyze
