Enzymes

Question 1

Factors effecting rate of enzyme controlled reaction

Answer 1

Factors effecting rate of enzyme controlled reaction

• Enzyme Concentration, rate increases as enzyme concentration increases as there are more active sites for substrate to bind to. However, increasing enzyme concentration beyond a certain point has no effect on rate as there are more active sites than substrates, so substrate concentration becomes the limiting factor
• Substrate Concentration, rate increases as substrate concentration increases as more enzyme-substrate complexes are formed. However, beyond a certain point the rate of reaction no longer increases as enzyme concentration becomes the limiting factor.
• Temperature, rate increases up to optimum temperature, rate of reaction decreases above optimum temperature

Question 2

Inhibitors

Answer 2

Inhibitors

• Irreversible inhibitors, (heavy metal ions) cause disulphide bonds in the protein structure to break causing the shape of the active site to change
• Reversable inhibitors, bind to active site using hydrogen bonds and weak ionic interactions. They can be competitive or non-competitive.
• Competitive, bind to active site of enzyme competing with substrate for enzyme, amount of product formed remains the same but rate is reduced
• Non-competitive, Binds to the allosteric site on the enzyme, This changes the shape of the active site, preventing binding of substrate. Increasing concentration of substrate has no effect on non-competitive inhibition

Question 3

Coenzymes

Answer 3

Coenzymes
- A cofactor is a non-protein compound required for the enzyme’s activity

• Coenzymes, are cofactors which do not bind permanently, they help binding of substrate to enzyme.
• Activators, are inorganic metal ions which temporally bind to enzyme and alter active site making reaction easier to occur
• Prosthetic Groups, permanently attached to the enzyme (haemoglobin contains a prosthetic haem group which binds to oxygen)