ENZYMES NAME: CHEBET MILTON CONTACT: Subject: Biology Topic: Nutrition
Learning objectives Define enzymes Classify enzymes Describe the mode of enzyme action (lock and key hypothesis) Do the mouse mischief exercises at the end using the given mice
Introduction to Enzymes What are enzymes biological catalysts, protein in nature which speed up and control the rate of chemical reaction in living organisms Classification of enzymes – Intracellular enzymes. – Extracellular enzymes.
Enzyme Action Learning objective: to describe different models for enzyme action and to investigate factors which control the rate of an enzyme reaction More free powerpoints at
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
Factors affecting 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 activity 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 activity Denaturing the protein
Effect of heat on enzyme activity 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
In this mischief exercise your are required to Highlight a word in the green (right hand) column and drag it into a middle box corresponding