Enzymes: “Helper” Protein molecules (Proteins in the body coded from DNA sequence)

How important are enzymes? All chemical reactions require enzymes building molecules synthesis enzymes breaking down molecules digestive enzymes enzyme + We can’t live without enzymes! enzyme +

How They work: lower activation energy

Definition Biological catalysts that speed up chemical reactions

Examples synthesis enzyme + digestion enzyme +

Enzymes are proteins Each enzyme is the specific helper to a specific reaction right shape for the job Examples sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA Oh, I get it! They end in -ase Sometimes named for the reaction they help

Enzymes aren’t used up Enzymes - not changed by the reaction re-used many times for the same reaction with other substrate molecules (10 million H2O2/hydrogen peroxide molecules broken down per second!) substrate product active site enzyme

It’s shape that matters! Lock & Key model Allow substrate to fit specific enzyme for each reaction

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Enzyme vocabulary Enzyme Substrate Products Active site helper protein molecule Substrate molecule that enzymes work on Products what the enzyme helps produce from the reaction Active site part of enzyme that substrate molecule fits into

What affects enzyme action Correct protein structure correct order of amino acids why? enzyme has to be right shape Temperature pH (acids & bases)

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

Temperature Effect on rates of enzyme activity Optimum greatest # of collisions between enzyme & substrate Human: 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 human enzymes 37 Degrees Celsius = Body temperature 37° What’s happening here?! 37° reaction rate temperature 37 Degrees Celsius = Body temperature

pH (Power of hydrogen) Effect on rates of enzyme activity changes in pH changes protein shape~ Denatures most human enzymes = pH 6-8 depends on where in body pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8

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

For enzymes… What matters? SHAPE!