•Enzymes make it easier for the reaction to take place by lowering the activation energy

•Enzymes are not reactants and therefore are not used up in the reaction

Enzymes are Proteins - long chains of amino acids that have taken on a specific shape

• They are catalysts- They may be used to break apart substrates with the use of water (hydrolysis)- They may be used to form new products plus water (condensation reactions)

Naming of Enzymes

At first enzymes were given the suffix “–in” to name them (ex: Pepsin, Trypin)

Now they receive the suffix “-ase” (ex: lactase, sucrase, maltase)

Sugars and other molecules often end in “-ose” (ex: lactose, glucose, fructose…)

EX: lactase breaks down lactose to make glucose and galactose

No need to write this down, just listen!

What are Substrates? Substrates are smaller than enzymes Substrates combine with enzymes to undergo

reactions Enzyme-substrate specificity – one key for

each lock analogy

SUBSTRATE

Enzyme-Substrate Complex Substrates bind with enzymes at the active site The shape of the enzyme determines the shape of

the active siteSubstrates with a different shape will not fit into the

active site and the reaction will not take place

Effects of Temperature

optimum temperature – temp in which enzymes work best

Reactions are dependent on molecular collisions. Fluids with higher temperatures move faster and therefore more collisions take place.

BUT, at a certain temperature the enzyme loses its specific shape, this is Denaturation. Then the enzymes and substrates can no longer bond.

Effects of pH Each enzyme has an optimum pH

Pepsin works best at pH 2 in the stomach

Trypsin works best at pH 8 in the small intestine

Effects of Substrate Concentration

The reaction goes faster if the substrate is more concentrated because there are more molecules to combine with but there is a limit called saturation.

Need to Know Example Lactase: As you age, your ability to produce

lactase decreases therefore you can no longer digest the lactose in dairy. These people are lactose intolerant.

To help people digest the lactose, companies will treat their products with lactase