What are the factors affecting Enzyme Activity?

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What are the factors affecting Enzyme Activity?
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Recap
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What are enzymes?

• Biological catalysts made up of proteins

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Function of Enzymes

• Enzymes speed up the rate of chemical reactions
  in the body both breaking down (e.g. starch
  into maltose)
  
  and building up reactions. (e.g amino acids into
  proteins).
• 
  
• Enzymes lower the activation energy required to
  start a chemical reaction

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Characteristics of Enzymes

• Enzymes are highly specific in action.
• Enzymes remain chemically unchanged at the end
  of the reaction.
• Enzymes are required in minute amounts.

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I. Name that Enzyme !!!

• Protein

ase
Substrate Name
-ase
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I. Name that Enzyme !!!

• Carbohydrate

ase
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Mode of Action

• Substrate fits in the enzyme active site,
• just like a key fits into a lock.
• An enzyme-substrate complex is formed.
• Chemical reactions occur at the active site and
  products are formed.

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What are the factors affecting Enzyme Activity?
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catalase
Hydrogen peroxide ? water and oxygen
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What affects enzyme activity?
Petri Dish 1 2 3 4 5
Condition of potato pieces Raw Cooked Frozen Soaked in Acid Soaked in Alkali
Observations
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0C

• Low temperatures ? low Kinetic Energy of enzymes
  and substrates.
• No/Very few enzyme-substrate complexes are
  formed.
• Enzymes are inactivated.

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20C (increasing temperature)

• Increasing the temperature will lead to the
  increase in kinetic energy of enzyme and
  substrate molecules.
• Enzyme and substrate molecules move with
  increasing speed and collide more frequently with
  each other.
• This increases the rate of enzyme-substrate
  complex formation This increases the rate of
  enzyme-substrate complex formation and product
  formation.

Rate of reaction increases
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37C

• As the temperature continues to increase, the
  rate of enzyme activity also increases until the
  optimal temperature is reached.
• Optimal temperature is the temperature at which
  the enzyme works best. Rate of product formation
  is highest!

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Beyond Optimal Temperatures

• At high temperatures (gt60C), weak bonds within
  the enzyme molecule are broken
• Enzyme loses its shape and its active site.
• Loss of shape leads to a loss of function.
  Enzyme is said to have denatured
• Denaturation is the change in 3D structure of an
  enzyme or any other protein caused by heat or
  chemicals such as acids or alkali, causing it to
  lose its function.

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Denaturation
Different enzymes denature at different
temperatures. Most enzymes denature at
temperatures higher than 60C. However, there
are some enzymes that stay active even at high
temperatures like 80C (Enzymes in the bacteria
Thermus aquaticus)
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Effect of pH on enzyme activity

• Enzyme works best within a narrow pH range
• Each enzyme works best at particular pH, known as
  its optimum pH level.
• At extreme pH levels, enzymes lose their shape
  and function and become denatured.

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Effect of pH on enzyme activity
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Effect of Substrate on Enzyme Activity
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