Enzymes The protein catalyst of life

Enzymes: The Video Clip

Enzyme Vocabulary Enzymes end in –aseEnzymes end in –ase Maltase binds to maltoseMaltase binds to maltose Lactase binds to lactoseLactase binds to lactose Lipase breaks down fatLipase breaks down fat Amylase is found in salivaAmylase is found in saliva Catalyst:Catalyst: Substance that affects the rate of a chemical reaction WITHOUT BEING ALTEREDSubstance that affects the rate of a chemical reaction WITHOUT BEING ALTERED Because it is not altered, can do same thing over, and, over, and, over, and over…….Because it is not altered, can do same thing over, and, over, and, over, and over……. Enzymes are ORGANIC CATALYSTSEnzymes are ORGANIC CATALYSTS

Enzyme Vocabulary Substrate:Substrate: The substance upon which the enzyme reactsThe substance upon which the enzyme reacts Active site:Active site: Site where enzyme binds to substrateSite where enzyme binds to substrate Denature:Denature: When enzyme’s shape is altered due to:When enzyme’s shape is altered due to: high temphigh temp strong acids or basesstrong acids or bases

How Do Enzymes Work? DEMO

Importance of Enzyme Shape Enzymes have specific shapesEnzymes have specific shapes This means enzymes are specific to their substrateThis means enzymes are specific to their substrate They will only attach to substrate that “fits” their shapeThey will only attach to substrate that “fits” their shape If shape of enzyme is denatured, will it be able to bind to its substrate?If shape of enzyme is denatured, will it be able to bind to its substrate? NO !NO ! Two things can cause denaturing:Two things can cause denaturing: TemperatureTemperature pHpH

Denaturing or Mutation of Enzyme: The Video Clip

Enzyme-Substrate Complex Formed when enzyme binds to substrateFormed when enzyme binds to substrate Very specificVery specific Lock and Key Model:Lock and Key Model: Enzyme-substrate complex often compared to a lock and keyEnzyme-substrate complex often compared to a lock and key Active site on enzyme can only “FIT” or bind to aActive site on enzyme can only “FIT” or bind to a specific substrate specific substrate Example: Amylase will bind to starch, but not celluloseExample: Amylase will bind to starch, but not cellulose

Enzyme-substrate Complex

The Enzyme Jingle! SUNG TO “JINGLE BELLS”! Shape, Shape, Shape Enzymes have a shape If active site is denatured It won’t bind suuu-uuuub-stra-ate Shape, shape, shape Enzymes have a shape Wrong pH or temperature Will affect its shape

What affects Enzyme Reaction Rates? Remember, enzymes speed up reactionsRemember, enzymes speed up reactions What can affect the rate at which enzymes perform?What can affect the rate at which enzymes perform? It’s shape!It’s shape! Denaturing affects rateDenaturing affects rate The amount of enzyme and substrate!The amount of enzyme and substrate!

Enzyme shape and reaction rate: Temperature Enzymes have a specific temperature range at which they work bestEnzymes have a specific temperature range at which they work best EX. Human enzymes work best at 37°CEX. Human enzymes work best at 37°C Temps not in the optimal range will cause enzymes to denatureTemps not in the optimal range will cause enzymes to denature Shape is altered, so reaction rates are SLOWED or stopped altogetherShape is altered, so reaction rates are SLOWED or stopped altogether Reaction rates will DROP dramatically depending on how much denaturing of enzyme DEMOReaction rates will DROP dramatically depending on how much denaturing of enzyme DEMO DEMO

Temperature vs. Reaction Rate

Enzyme shape and reaction rate: pH Enzymes have a specific pH range at which they work bestEnzymes have a specific pH range at which they work best EX. Most enzymes work best at pH 7EX. Most enzymes work best at pH 7 Where in the body would enzymes be optimal at a low (acidic) pH? Why?Where in the body would enzymes be optimal at a low (acidic) pH? Why? In stomach. This is because stomach acid has a low pHIn stomach. This is because stomach acid has a low pH pH not in the optimal range will cause enzymes to denaturepH not in the optimal range will cause enzymes to denature Shape is altered, so reaction rates are SLOWED or stopped altogetherShape is altered, so reaction rates are SLOWED or stopped altogether Reaction rates will DROP dramatically depending on how much denaturing of enzyme DEMOReaction rates will DROP dramatically depending on how much denaturing of enzyme DEMO DEMO

pH vs. Reaction Rate

Enzyme amount and reaction rate Enzyme rate also depends on the amount of enzyme and substrateEnzyme rate also depends on the amount of enzyme and substrate Little enzyme, lots o’ substrate:Little enzyme, lots o’ substrate: Slower ratesSlower rates How can we speed up the rate?How can we speed up the rate? Add more enzyme until max. rate achieved.Add more enzyme until max. rate achieved.

Substrate Concentration vs. Reaction Rate