Enzymes

What are enzymes?

• Biological catalysts
• Inside cells
  • protein/lipid synthesis
  • intercellular
• Outside cells
  • digestion
  • extracellular
• Globular proteins
• Generally soluble in water
• Functions
  • Speed up a reaction
    • Help build a larger molecule
    • Help breakdown a large molecule into multiple smaller ones

Activation energy

• Amount of energy which needs to be supplied for a reaction to proceed.
• Enzymes reduce activation energy requirements (due to their specific shape)

Induced fit hypothesis

• Substrate molecules collide with enzyme’s active site

• Enzyme molecule changes shape slightly. Active site fits more closely around substrate.

• Enzyme-substrate complex (ESC) is formed.

• Substrate destabilised

• Product produced

• Enzyme-product formed

• Product leaves enzyme active site

• All enzymes are globular proteins

  • More beta pleated sheets than alpha helix

• Many hydrophilic R groups

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