How Enzymes do catalysts speed up chemical reactions

Catalysts � Activation energy is energy needed to start a chemical reaction � Sometimes…activation

Enzymes Function as Catalysts � Enzymes are catalysts for organisms ◦ They lower the

Enzymes Function as Catalysts � Enzymes are: ◦ Specific - they only bind with

What affects enzyme action 1. 2. 3. Correct protein structure ◦ correct order of

Order of amino acids � Wrong order = wrong shape = can’t do its

Temperature � Effect on rates of enzyme activity ◦ Optimum temperature �greatest number of

Temperature reaction rate human enzymes 37° temperature What’s happening here? !

p. H � Effect on rates of enzyme activity ◦ changes in p. H

p. H intestines trypsin What’s happening here? ! reaction rate stomach pepsin 0 1

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• How Enzymes do catalysts speed up chemical reactions? • How do enzymes function as catalysts?

Catalysts � Activation energy is energy needed to start a chemical reaction � Sometimes…activation energy required is greater than the energy present so a catalyst is required ◦ Catalysts: � lower the activation energy a reaction needs and �increase the rate of reactions ◦ Examples of catalysts: heat, stirring, crushing

Enzymes Function as Catalysts � Enzymes are catalysts for organisms ◦ They lower the activation energy and increase the rate of reactions � Enzymes are proteins � Their function depends on their shape ◦ Lock/Key analogy Enzyme binds to substrate Reaction occurs Enzyme and Product separate

Enzymes Function as Catalysts � Enzymes are: ◦ Specific - they only bind with certain substrates � Substrates bind to enzymes by attaching to their active sites ◦ The enzyme then bends around the substrate (induced fit)

What affects enzyme action 1. 2. 3. Correct protein structure ◦ correct order of amino acids ◦ why? enzyme has to be right shape Temperature ◦ why? enzyme has to be right shape p. H (acids & bases) ◦ why? enzyme has to be right shape

Order of amino acids � Wrong order = wrong shape = can’t do its job! chain of amino acids DNA folded protein right shape! folded protein chain of amino acids DNA wrong shape!

Temperature � Effect on rates of enzyme activity ◦ Optimum temperature �greatest number of collisions between enzyme & substrate �human enzymes � 35°- 40°C (body temp = 37°C) ◦ Raise temperature (boiling) �denature protein = unfold = lose shape ◦ Lower temperature T° �molecules move slower �fewer collisions between enzyme & substrate

Temperature reaction rate human enzymes 37° temperature What’s happening here? !

p. H � Effect on rates of enzyme activity ◦ changes in p. H changes protein shape~ Denatures ◦ most human enzymes = p. H 6 -8 �depends on where in body �pepsin (stomach) = p. H 3 �trypsin (small intestines) = p. H 8

p. H intestines trypsin What’s happening here? ! reaction rate stomach pepsin 0 1 2 3 4 5 6 p. H 7 8 9 10 11 12 13 14

For enzymes… What matters? SHAPE!