Enzyme Action Learning objective: to describe different models for enzyme action and to investigate factors which control the rate of an enzyme reaction 18 th October
Lock and Key
However certain substances can bind to the enzyme at sites other than the Active site and modify its activity (inhibitors/co-factors) Idea that the enzyme is flexible
Induced Fit
Enzyme reactions enzyme + substrateenzyme-substrate complex
Enzyme reactions enzyme + substrateenzyme-substrate complex E +S ES
Enzyme reactions enzyme + product enzyme-substrate complex E +PES enzyme + substrateenzyme-substrate complex E +S ES
Enzyme activity How fast an enzyme is working Rate of Reaction
Enzyme activity How fast an enzyme is working Rate of Reaction Rate of Reaction = Amount of substrate changed (or amount product formed) in a given period of time.
Rate of Reaction Enzyme activity Variable you are looking at
Enzyme activity Four Variables
Enzyme activity Four Variables Temperature pH Enzyme Concentration Substrate Concentration
Rate of Reaction Temperature
Rate of Reaction Temperature
Rate of Reaction Temperature o C - denatures o C Increase in Activity <5 o C - inactive
Effect of heat on enzyme activty If you heat the protein above its optimal temperature bonds break meaning the protein loses it secondary and tertiary structure
Effect of heat on enzyme activty Denaturing the protein
Effect of heat on enzyme activty Denaturing the protein ACTIVE SITE CHANGES SHAPE SO SUBSTRATE NO LONGER FITS Even if temperature lowered – enzyme can’t regain its correct shape
Rate of Reaction pH
Rate of Reaction pH
Rate of Reaction pH Narrow pH optima
Rate of Reaction pH Narrow pH optima WHY?
Rate of Reaction pH Narrow pH optima Disrupt Ionic bonds - Structure Effect charged residues at active site
Rate of Reaction Enzyme Concentration
Rate of Reaction Enzyme Concentration
Rate of Reaction Substrate Concentration
Rate of Reaction Substrate Concentration
Rate of Reaction Substrate Concentration Active sites full- maximum turnover
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