Lecture 20 Flashcards
What energy does binding the transition state lower?
𝛥G‡
What do enzyme active sites bind better to?
The enzyme rather than the substrate
What creates the activation energy barrier?
The high energy state that is associated with the intermediate
What is Preferential Transition State Stabilization?
A term used to describe that enzyme active sites will prefer to bind to the transition state over the substrate
What does it mean if an enzyme is able to bind more strongly to the transition state relative to the substrate?
The greater the catalytic activity of the enzyme and the more favorable to reaction is going to be
What are substrate or transition state analogs?
Things that look like but are not quite the substrate for a particular enzyme
What are potent inhibitors of many enzymes?
Transition state analogs
What do transition state analogs bind to and with what affinity?
The enzyme with higher affinity compared to the substrate
What kind of curve is seen in a Reaction Velocity vs Concentration Substrate graph?
A hyperbolic curve
What is Vmax on a reaction velocity vs. concentration of substrate curve analogous to?
100% binding of a ligand binding protein
What is Vmax?
The maximum rate at which an enzyme can catalyze the conversion of substrate into products
What does the Plateau region on a reaction velocity vs concentration of substrate graph represent?
When all the active sites are occupied with substrate as part of the reaction that is being cata;yzed
What determines Vmax in a Reaction Velocity vs Concentration of Substrate curve?
The amount of enzyme present
What is the formula for Vmax in a Reaction Velocity vs Concentration of Substrate curve?
𝛥[Product]/𝛥time
What does Km (the Michaelis constant) represent?
The substrate concentration at which the reaction velocity is 50% of the Vmax
What is Km analogous to?
Kd in ligand binding
What does a smaller value of Km meaning?
The more steeper the hyperbola, and the more rapidly we would see conversion of substrate into product
What is V0 on a Reaction Velocity vs Concentration of Substrate curve?
The rate that we see product being formed when the enzyme and the substrate are initially mixed together
When does V0 = 50% Vmax?
When [substrate] = Km
What are the six mechanisms for regulation of enzyme activity?
- Competitive inhibition
- Allosteric
- Reversible covalent modification
- Ionic signals
- Regulation gene expression
- Changes in subcellular localization
Which mechanisms for regulation of enzyme activity affect the intrinsic activity of an enzyme?
- Competitive inhibition
- Allostery
- Reversible covalent modification
- Ionic signals
Which mechanisms for regulation of enzyme activity do not affect the intrinsic activity of an enzyme?
- regulation of gene expression
* changes in subcellular localization
How can allostery effect regulation of an enzyme?
Changing the shape of a protein that is involved in catalyzing the reaction to increase or decrease the activity of the enzyme
What is reversible covalent modification?
Changing the tertiary structure of proteins in some fashion covalent
