ENZYMES

What’s an Enzyme? Enzymes are proteins. Enzymes are catalysts. Catalysts speed up chemical reactions End in –ase (Ex: sucrase, catalase) Without an enzyme! With an enzyme!

WARNING Superman had Kryptonite Mrs. Head had Organic Chemistry Enzymes have Acids (pH) Cold Temperatures Extreme Hot Temps slow down the enzyme and the chem. reaction

Chemical Reactions Reactants → (yield) Products Ex: Fe + O2 → rust

Why do we need Enzymes? Speed up rate of chemical reaction by lowering the activation energy (energy needed to start chemical reaction) Without enzyme Activation energy without enzyme Activation Energy with enzyme Reactants With enzyme Products

How do ENZYMES work? The enzyme attaches to reactants The reactants that bind to the enzyme are known as the substrates. The part of the enzyme where the substrate attaches to the enzyme is called the active site. The shape of the active site only fits the shape of the substrate, like a lock fits a key. Only the correct substrate binds to the enzyme.

Lock-and-Key Mechanism- Enzymes can only bind to certain substrates Reactants/ Substrates Enzyme Lock-and-Key Mechanism- Enzymes can only bind to certain substrates

How do you speed up enzymes? Add more of the enzyme. Warm up the enzyme! Don’t warm it too much or something may happen

Once the enzyme and substrate are together, the enzyme holds the substrate so the reaction can occur. Once the reaction is over, the enzyme unlocks the product and the enzyme can start a new reaction with an identical substrate. Enzymes are not permanently changed or used up in reactions

A change in the pH of the enzyme can cause a change in the shape of the active site, therefore changing the activity of the enzyme.

Effect of Enzymes Reaction pathway without enzyme Activation energy Reactants Activation energy with enzyme Reaction pathway with enzyme Products Go to Section:

Figure 2-19 Chemical Reactions Section 2-4 Energy-Absorbing Reaction Energy-Releasing Reaction Products Activation energy Activation energy Reactants Reactants Products Go to Section: