2.5 investigate the effects of the environment on enzyme activity through the collection of primary or secondary data

Temperature

• Enzymes in humans usually have an optimum temperature of 37.5° C

• As temperature increases, enzyme activity increases

• Increasing temperature makes the enzyme and substrate particles vibrate faster, making it more likely for collisions to occur between the active site and the substrate

• Temperatures above the optimum begin to break the bonds between the amino acids that the enzyme is made of

• As the bonds break, the shape of the active site changes so it no longer fits the substrate, denaturing the enzyme

pH

• The pH scale measures from 0 (acidic) to 14 (alkaline)

• Deviation from the optimum pH begins to denature the enzyme, as with temperature

• Enzymes can tolerate small changes in pH, but if the change is too large the damage is irreversible

Substrate Concentration

• Large amounts of substrate can trigger/activate enzymes

• As substrate concentration increases, reaction rate increases until all active sites are occupied. This is called the saturation point
  

Enzyme Concentration

• The concentration of enzyme affects how much substrate can be acted upon

• Increasing enzyme concentration does not always result in a greater rate of enzyme activity, as enzymes are not used up during reactions

Presence of Salt

• Ions in the salt can interfere with the intermolecular forces between enzymes

Enzyme Inhibitors

• Enzyme inhibitors compete with the substrate for the active site. There are two types of inhibitors:

  • Competitive - Occupies the active site so that the substrate cannot bind to it

  • Non-competitive - Binds to some other part of the enzyme, making it harder for the substrate to bind to the active site but not stopping it completely

Cofactors & Coenzymes

• Sometimes, cofactors and coenzymes are needed in order for an enzyme to catalyse a reaction

  • Cofactors - Bind permanently to an enzyme, increasing the speed of the reaction. They are metal ions, such as K+ and Zn2+

  • Coenzymes - Carry chemical groups between enzymes, loosely binding to them. They are organic molecules, such as Biotin and Vitamin B