BME 205: Lab 6 Final Review

What is an enzyme?

Molecules that accelerate the rate of a reaction within a biological system

Do enzymes accelerate forward and backward reactions?

Yes

Do enzymes change the overall free energy change of a reaction?

No

How do enzymes act?

Bind and stabilize the transition state of a reaction by lowering the free energy of the activation

What is the initial reaction velocity?

Rate of change in product concentration per unit time; initial rate of a reaction

In low concentrations, how do you calculate Vo?

Vmax/Km

What is Vmax?

The maximum rate of reaction which occurs when the enzyme is completely saturated with substrate

What does Vmax reveal?

The turnover number

What is the turnover number?

The maximum number of substrate molecules that can be converted to product by each enzyme per second

What does Km represent?

Michaelis-Menten constant; the measure of an affinity of an enzyme for its substrate

What is the relationship between Km and affinity?

Inverse; Km up Affinity down

What are the axes on a Lineweaver-Burk plot?

1/v vs 1/[s]

What is the slope of the Lineweaver-Burk plot?

Km/Vmax

What is the y-intercept of a Lineweaver-Burk plot?

1/Vmax

What is the x-intercept of a Lineweaver-Burk plot?

-1/Km

Where do you measure Km on a Michaelis-Menten graph?

At Vmax/2

What is competitive inhibition?

A compound binds to the enzyme and restricts access (substrate cannot bind)

What is noncompetitive inhibition?

Both the substrate and other compound can bind simultaneously but the complex cannot become a product

What is uncompetitive inhibition?

Inhibitor can only bind to the enzyme once the substrate has been bound (rare)

How does a competitive inhibitor affect a MM plot?

Km: upVmax: sameActive Site: Occupied

How does a noncompetitive inhibitor affect a MM plot?

Km: equal Vmax: down Active Site: Not Occupied

What is valuable about a LB plot?

Most valuable plot for determining inhibitor types

What is the MM equation?

Vo= Vmax[S]/Km+[S]