Lock & key vs induced fit

• What are enzymes made of?


  Globular proteins
• What is their shape (e.g. active site) determined by?


  Complex tertiary structure.
• If an enzymes shape is determined by the complex tertiary structure what does this mean?


  It's highly specific
• When was the first model of enzyme activity described and by whom?


  Emil Fischer
• What did Emil suggest?


  Both enzymes and substrates were rigid structures that locked into each other very precisely, muck like a key going into a lock.
• What is the modified model of enzyme activity known as?


  The induced-fit hypothesis
• How is the induced fit different to the lock & key?


  The enzyme and its active site (and sometimes the substrate) can change shape slightly as the substrate molecule enters the enzyme.
• What are these changes known as?

  Conformational changes
• How does this improve enzyme activity?


  It ensures an ideal binding arrangement between the enzyme and substrate is achieved.

  This maximises the ability of the enzyme to catalyse the reaction.