Enzymes Helper Protein molecules What are enzymes An

Enzymes: “Helper” Protein molecules

What are enzymes? • An enzyme is a biological catalyst that makes chemical reactions in cells possible.

Examples § synthesis + enzyme § digestion enzyme +

Chemical reactions of life • Enzymes can help in: – building molecules • synthesis + – breaking down molecules • digestion +

Nothing works without enzymes! • How important are enzymes? – all chemical reactions in living organisms require enzymes to work enzyme • building molecules – synthesis enzymes • breaking down molecules We can’t live without enzymes! – digestive enzymes – enzymes speed up reactions • “catalysts” + enzyme +

Enzymes • A protein catalyst • Enzymes are important proteins found in living things. An enzyme is a protein that changes the rate of a chemical reaction. • They speed metabolic reactions.

• Enzymes do not catalyze processes that would not take place on their on. They just make processes take place faster!

Enzymes aren’t used up • Enzymes are not permanently changed or used up in reactions. – used only temporarily – re-used again for the same reaction with other molecules – very little enzyme needed to help in many reactions substrate active site product enzyme

Enzymes are proteins • Each enzyme fits only one specific type of reaction, but can catalyze many of this particular reaction one after another. – each enzyme needs to be the right shape for the job – enzymes are named for the reaction Oh, I get it! they help They end in -ase • • sucrase breaks down sucrose proteases breakdown proteins lipases breakdown lipids DNA polymerase builds DNA

Substrates • Substrate – A molecule that enzymes work on – Substrates undergo chemical changes to form new substances called products. • Products – what the enzyme helps produce from the reaction • Active site – part of enzyme that substrate molecule fits into

It’s shape that matters! • Lock & Key model – shape of protein allows enzyme & substrate to fit – specific enzyme for each specific reaction

Activation Energy • The activation energy of a reaction is the minimum amount of energy needed to start a reaction. • It is like traveling over a hill because the peak represents the activation energy needed for the reaction.

What affects enzyme action • The rate of a reaction depends in part on the shape of the enzyme. If the enzyme is large, its concentration is high, which increases reaction rate. • Correct protein structure – correct order of amino acids – why? enzyme has to be right shape • Temperature • p. H (acids & bases) – why? enzyme has to be right shape

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

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

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

Other important facts about enzymes! • Enzymes are a type of protein! • Enzymes usually end in the suffix –ase. • Examples: – Carbonic anhydrase: removes carbon dioxide from the blood before it becomes toxic. – Lipase: speeds up the digestion of fats – RNA polymerase: speeds up protein production

Enzyme Disorders • PKU: phenylketonuria *Cells fail to make an enzyme that is used to break down phenylalanine. *If phenylalanine builds up in the blood, it can cause death.

• Tay-Sachs: *It is a genetic disease that affects the human brain. *In this disease, cells do not produce an enzyme that breaks down lipids. *Over time, the buildup of lipids in and around the brain cells causes blindness, seizures, and usually death.

For enzymes… What matters? SHAPE!