1.6 Enzyme Kinetics Flashcards
How are enzymes classified and organized?
According to the type of reaction they catalyze
T or F, Enzymes are biocatalysts that increase the rate of chemical reactions and are consumed during the reaction
False. They are NOT consumed during the reaction
What is an enzyme and its cofactor called?
Holoenzyme
What is an Apoenzyme
The protein portion of the holoenzyme
Prosthetic groups
Tightly bound coenzyme
Three types of enzymatic reactions?
- Random
- Sequential Displacement
- Double Displacement (ping-pong)
What is Double displacement enzymatic reactions
When one or more products are released before all substrates have been bound by enzyme
Rate of reaction in enzyme kinetics is directly proportional to what?
[E] and [S]
Allosteric enzymes give what type of curve on the substrate vs V0 graph?
Sigmoidal curve
What is the Km
It reflects the affinity of the enzyme for the substrate
Km = what?
the [substrate] at 1/2 Vmax
T or F, Km varies with Enzyme concentration?
False, It does not vary with enzyme concentration. It is dependent upon the [S]
Small Km = what type of affinity that E has for S
A high affinity
_______ Km = low affinity of E for S
Large Km
What does the slope represent on the Lineweaver-Burke plot
slope = Km/Vmax
What is the x axis on the Lineweaver-Burke plot
1/[S]
Y-axis of the Lineweaver-Burke plot
1/V0
What is the turnover number
number of molecules of [S] converted to product per enzyme per second
High Kcat and low Km are markers of what?
Enzyme efficiency
Explain reversible enzyme inhibition
Enzyme inhibition in which there are noncovalent bonds used and the enzyme can continue functioning
What is irreversible enzyme inhibition
Enzyme does not regain activity
What are the two most common reversible enzyme inhibitions
- Competitive
2. Non-competitive
Which type of inhibitor reduces rate of catalysis by reducing the proportion of enzyme molecules bound to a substrate?
Competitive inhibitor
What type of inhibitor functions by binding to the enzyme at a different location than the active site?
Non-competitive inhibitor
What type of enzyme inhibitor increases the Km
Competitive Inhibitor
What happens to a competitive inhibitor if extra substrate is added
The inhibition can be dampened
Which inhibitor decreases the Vmax and keeps Km the same
Noncompetitive Inhibitor
Why does a noncompetitive inhibitor not affect the Km
The inhibitor does not interfere with the substrate and enzyme binding.
What is an Isozyme?
Alternative form of same enzyme activity that exist in different proportions in different tissues
What is a Proenzyme or a Zymogen
Inactive storage forms of enzymes
