1.4.2: Many proteins are enzymes

Explain part A of this graph (substrate concentration)

• Available / free active sites

• Increase in substrate concentration

• Increase in enzyme-substrate complexes

• Increase in rate of reaction

Explain part B of this graph (substrate concentration)

• No available active site

• Increase in substrate concentration

• No increase in enzyme-substrate complexes

• Rate of reaction stays constant

Explain part A of this graph (enzyme concentration)

• Available substrates

• Increase in enzyme concentration

• Increase in enzyme-substrate complexes

• Increase in rate of reaction

Explain part B of this graph (enzyme concentration)

• No available substrate molecules

• Increase in enzyme concentration

• No increase in Enzyme-substrate complexes

• Rate of reaction stays the same

How do competitive inhibitors work?

• Their molecular shape is similar to the substrate

• The molecules can bind to the outside of an enzyme

• The inhibitor is not permanently bonded to the enzyme, so a substrate can still the active site once the inhibitor leaves

• An increase in the concentration of substrates decreases the effect of the inhibitor

• Less enzyme-substrate complexes are formed which leads to a lower rate of reaction

How do non-competitive inhibitors work?

• Bind to the enzyme at a location other than the active site

• The inhibitor then changes the shape of the enzyme so the substrate is no longer complimentary to the active site

• Less enzyme-substrate complexes form so the rate of reaction islower

• An increase in the concentration of substrates has no effect on how these inhibitors work