Enzymes Enzymes Enzymes are proteins made of amino

Enzymes

Enzymes • Enzymes: are proteins made of amino acids. -Catalyst: they speed up chemical reactions & lower the activation energy. the -Reusable: remain unchanged after reaction for a -specific: there is a perfect enzyme certain substrate

Are Enzymes reusable? Yes or NO

Enzymes are…. . A. Nucleic Acids B. Carbohydrates C. Proteins D. Lipids

Enzymes • 3 D shape • can be destroyed & denatured (change shape) with extreme changes in p. H & temperature • have active sites = places where substrate (food & waste) molecules attach

Examples of Enzymes Catalase breaks down hydrogen peroxide (waste produced in cells) into water and oxygen 2 H 2 O 2 ----> 2 H 2 O + O 2 milk Lactase breaks down lactose in Protease breaks down proteins Lipase breaks down lipids

How Enzymes Work? • Active sites on enzymes = places where a specific substrate binds • Enzyme-substrate complexes form (when substrates attach to active sites on the enzymes) to break apart or put together substances at a fast rate • E+ S ES E +P

What are active sites?

Two Model of Enzymes 1. lock & key model → substrate & the enzyme fit together perfectly 2. induced-fit model →enzymes change shape slightly to accommodate the substrate

Lock & Key Model

Induced-Fit Model

Factors Affecting Enzyme Action • Temperature – enzymes work best at certain temperatures (– 37 o. C is best for human enzymes in the body) • p. H – enzymes work best at certain p. H; basic, neutral, and/or acidic environments ex. ) Amylase in saliva at p. H 7, Pepsin in the stomach at p. H 2 -3, Trypsin in the intestines at p. H 9

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

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 Factors Affecting Enzyme Action • Substrate & enzyme concentrations – how fast reactions take place depends on how much of the substrate & enzyme is available. • Coenzymes – helpers such as vitamins & minerals