(10+11) Enzyme Function, Regulation, and Kinetics

Enzymes are proteins that serve as a _

catalyst

Activation energy (Ae)

extra energy required to take a molecule to a higher or lower energy state

How do enzymes act as a catalyst?

they reduce activation energy to a lower level

Substrate ligand

ligand which is the target of an enzyme.

What is the binding site of a enzyme called?

active binding site

What are some ways enzymes reduce activation energy

it holds the substrate in the correct orientation, it transfers some of the binding energy to the catalysis of the reaction

The typical enzyme can bind to a substrate ligand around _ times a second

1000

When graphing the activity of an enzyme what is the y axis and the x axis?

y axis is enzyme activity/ velocity/ amount of substrate converted to product divided by time. X axis is the concentration of substrate

If you increase the concentration of substrate, the activity of the enzyme will (increase or decrease?). Is there a limit to the amount that this will increase/decrease?

the activity will increase until the enzyme is saturated (seen on this graph where it flattens out)

What are some ways to regulate enzymatic activity (in order from fastest to slowest)

, regulatory ligands which cause change in Km, changing substrate concentration, and changing enzyme concentration

Regulatory binding site

binding site on an enzyme which binds to a regulatory ligand. When this occurs it can alter how the substrate binds to the active site.

Regulatory ligand

ligand which binds to the regulatory binding site of an enzyme. This causes the enzyme to change shape slightly in order to decrease or increase substrate binding.

Positive modulator

regulatory ligand which changes the shape of an enzyme and causes the substrate to bind more easily to the active site of an enzyme

negative modulator

regulatory ligand which changes the shape of an enzyme and causes the substrate to bind less easily to the active site of an enzyme

Draw a graph of enzyme activity with no modulator, positive modulator and negative modulator

Vmax

aka saturation point. Maximum velocity than an enzyme will obtain under any conditions

Michaelis constant (Km)

=[S] at ½Vmax

Draw a graph of enzyme activity and indicate where Vmax and Km is at

arrow line shows where the Km is

When Km increases what does that indicate? When it decreases?

increase in Km indicates a decrease in the affinity of the enzyme for its substrate. Decrease in Km indicates an increase in enzyme affinity.

t/f enzymes may have up to 1 regulatory binding sites

false; enzymes may have multiple regulatory binding sites

is a cofactor that may be required for some enzymes to work

ATP (energy)