Factors affecting enzyme activity

What factors affect enzyme activity

• Temperature

• pH

• Enzyme concentration

• Substrate concentration

What is the optimum temperature for enzyme activity

37°C begins to denature around 40°C and activity begins to fall below 37°C

How does temperature affect activity

Higher temperatures means there is more KE so atoms in enzyme vibrate more which breaks bonds in tertiary structure of enzyme so active site changes and substrate no longer complimentary.

Lower temperatures there is less KE for enzymes and substrate so there are less successful collisions, so less enzyme substrate complexes so rate of reaction decreases.

What is the temperature coefficient (Q10) and the equation

Every 10°C increase the rate of reaction doubles.

The equation is Q10=rate of reaction at (T+10)°C/ rate of reaction at T°C

What is the optimum pH

Usually around pH7-8 but some enzymes work at extreme pH

How does pH affect enzyme activity

pH changes concentration of H⁺ ions which interact with amino acids, this disrupts ionic bonds and hydrogen bonds so tertiary structure changes so active site changes and is no longer complimentary to substrate

How enzyme/ substrate concentration affects enzyme activity

If there is more enzymes there are more active sites for substrates to bind to, more substrates mean more can bind to active site of enzyme increasing rate of reaction until V max

What is V max

This is the maximum rate of reaction, at this point all active sites are occupied by substrate particles and no more enzyme-substrate complexes can form until products released. Only way to increase ror is by adding more enzyme or increasing temperature

If a reaction was carried out with optimum conditions and excess substrate what would the shape of the line be on the graph

A straight line

What information needs to be given for reproducible results of a pratical

• pH as different pH may affect rate of reaction slow it down or speed it up

• Concentration of enzyme as may speed up rate of reaction