Enzymes, Their Regulation + Kinetics Flashcards
Types of regulators (inhibitors, activators), Km, Vmax, MM + LB plots
What are some general need-to-know properties of Enzymes?
Enzymes are biological catalysts, they are almost always proteins, and are NOT consumed in a reaction. They are also very specific in action.
What are the actions of a Competitive Inhibitor?
A competitive inhibitor is structurally similar to the substrate (looks similar, you will be able to tell) and it competes with the substrate for the active site. At low concentrations of substrate, the inhibitor reduces the reaction rate, but it can be over run by large amounts of substrate. When added, Vmax will NOT CHANGE, but Km will INCREASE.
What are the actions of a Non Competitive Inhibitor?
Non Competitive inhibitors bind away from the active site. Both substrate and inhibitor are bound. Enzyme activity is reduced, Vmax will DECREASE, but Km will NOT CHANGE.
Describe a Lineweaver-Burk plot and what information it provides
The X-axis is 1/[S]
The Y-axis is 1/V (reaction velocity)
Vmax = 1/X-axis
Km = 1/Y-axis
Describe a Michaelis-Menten plot and what information it provides
The plot would have an X-axis of Substrate concentration, and a Y-axis of reaction rate. The Vmax can be estimated, and the Km would be half of the Vmax.
what is Covalent Modification?
Regulation of an enzyme by addition or removal of a group to the enzyme through a covalent bond.
ex. glycogen phosphorylase - active in phosphorylated state; inactive in dephosphorylated state
Is the active site located on the catalytic domain or the regulatory domain?
The Catalytic domain
does changing enzyme concentration affect Vmax and Km?
It will directly affect Vmax, Km is a constant and therefore will not change
What is the difference between a Kinase and a Phosphatase enzyme?
Kinase- catalyses the addition of a P group
Phosphatase- catalyzes the removal of a P group
What factors affect an enzymes reaction rate?
-Temperature (as temp increases, rxn rate increases until the protein denatures)
-pH sensitive
-amount of enzyme (linear with Vmax)
-amount of substrate (linear with rxn rate)
