Michaelis Menten Enzyme Kinetics

# Michaelis Menten Equation and Graph

The equation for this curve is:

where v is the reaction rate, v_{max} is the maximum reaction rate, K_{m} is the concentration at which the reaction is running at half the maximum rate, and [S] is the concentration of the substrate.The graph starts at 1st order with low [S], then becomes 0th order as S approaches infinity.

# Lineweaver Burk Equation and Graph

The equation for this curve is:

This equation is simply derived from the equation above. The axes are both reciprocals of the axes on the graph above. This linear equation provides a good way to easily find v_{max} and K_{m}.

# Notes on Inhibition

- Competitive: The inhibitor binds to and blocks the enzyme’s active site. This does not change the v
_{max}, but it does increase K_{m}.- In a Michaelis Menten plot,the max height will stay the same, but the rate will rise less steeply as concentration increases.
- In a Lineweaver Burk plot, the line grows more steep and the x intercept (which is negative) moves closer to x = 0.

- Noncompetitive: The inhibitor binds to the enzyme in a place where it just makes the enzyme work less efficiently. This does not change K
_{m}, but it decreases v_{max}.- In a Michaelis Menten plot, v
_{max}will decrease, so ½*v_{max}will decrease as well. Make sure the K_{m}for the new, lower ½*v_{max}is the same as the old K_{m}for the old, higher ½*v_{max}. - In a Lineweaver Burk plot, the line grows more steep (again), but this time because the y intercept gets bigger.

- In a Michaelis Menten plot, v
- Uncompetitive: The inhibitor can only bind to the complex formed by the enzyme and substrate. This lowers K
_{m}and lowers v_{max}.- In a Michaelis Menten plot just check to make sure both K
_{m}and v_{max}are changing. - In a Lineweaver Burk plot, the new line will be parallel to the old line, but will have a larger x and y intercept.

- In a Michaelis Menten plot just check to make sure both K