6.3 Enzymes

What are Enzymes?

• Enzymes are proteins.

• Enzymes are made up of long chains of amino acids held together by peptide bonds.

What are Enzymes?

• Enzymes are catalysts – they help or speed chemical reactions with out being used up themselves.

• Enzymes can be reused over and over.

What are Enzymes?

• Enzymes help with chemical reactions such as digestion and breathing, blood clotting, healing of wounds, controlling the production of hormones, destroying pathogens and environmental toxins, etc.

There are three types of enzymes

• metabolic• digestive • food enzymes

Metabolic enzymes • Made by the body itself

• Mainly responsible for reactions related to detoxification and energy production.

• Even though, these enzymes are produced by almost all living cells, cells in the liver, gallbladder, pancreas, etc., make most of the metabolic enzymes

Catalase

• Catalase is the enzyme that catalyzes the decomposition of hydrogen peroxide into water and oxygen.

• 2H2O2 -> 2H2O + O2

• One molecule of catalase can break 40 million molecules of hydrogen peroxide each second.

Carbonic anhydrase

• Carbonic anhydrase is the enzyme found in red blood cells where it catalyzes the reaction

• CO2 + H2O ↔ H+ + HCO3− • It enables red blood cells to transport

carbon dioxide from the tissues to the lungs.

• One molecule of carbonic anhydrase can process one million molecules of CO2 each second.

Digestive enzymes

• Made by the body itself

• include the chemical reactions that break down the food we eat and convert them into energy. These enzymes are secreted along the digestive tract.

• Enzymes that break down proteins into amino acids = pepsin, trypsin and peptidases

• Enzyme that break down starch into simple sugars = amylase

• Enzyme that breaks down fat into glycerol and fatty acids = lipase

• Specific enzymes work on specific foods. You need the right type of enzyme for the foods you want it to break down.

• On the next two slides are a list of the common enzyme types and foods they act on.

The major different types of digestive enzymes are:

amylase – breaks down carbohydrates and starches which are prevalent in potatoes, fruits, vegetables, and many snack foods

lactase – breaks down lactose (milk sugars)

diastase – digests vegetable starch

sucrase – digests complex sugars and starches

maltase – digests disaccharides to monosaccharides (malt sugars)

invertase – breaks down sucrose (table sugar)

glucoamylase – breaks down starch to glucose

alpha-glactosidase – facilitates digestion of beans, legumes, seeds, roots, soy products, and underground stems

The major different types of digestive enzymes are:

protease – breaks down proteins found in meats, nuts, eggs, and cheese

peptidase – breaks down small peptide proteins to amino acids

trypsin – derived from animal pancreas, breaks down proteins

alpha – chymotrypsin, an animal-derived enzyme, breaks down proteins

papain – derived from raw papaya, broad range of substrates and pH, works well breaking down small and large proteins

lipase – breaks down fats found in most dairy products, nuts, oils, and meat

Food enzymes

• We get them from the raw food we eat or by taking enzyme supplements.

• Enzyme that breaks responsible for digesting fibers is not produced by the body = cellulase

• Enzymes bind temporarily to one or more of the reactants of the reaction they catalyze.

• The substrate binds to the active site of an enzyme.

• When the enzyme binds to the substrate, they lower the amount of activation energy needed and thus speed up the reaction.

• E = Enzyme - the catalyst, • S = Substrate – what is being broken

down• P = Product – what is being made

How the enzyme works• 1. An enzyme and a substrate are in the same area. The

substrate is the biological molecule that the enzyme will attack.

•2. The enzyme grabs onto the substrate with a special area called the active site The active site is a specially shaped area of the enzyme that fits around the substrate. The active site is the keyhole of the lock.

• 3. A process called catalysis happens. Catalysis is when the substrate is changed. It could be broken down or combined with another molecule to make something new.

• 4. The enzyme lets go. Big idea. When the enzyme lets go, it returns to normal, ready to do another reaction. The substrate is no longer the same. The substrate is now called the product.

Enzyme activity is effected by ~ Temperature

• Proteins change shape as temperatures change.

• Because so much of an enzyme's activity is based on its shape, temperature changes can mess up the process and the enzyme won't work.

Enzyme activity is effected by ~ pH Levels

• In the same way temperature changes the shape of proteins, the acidity of the environment does the same thing.

• Remember that the pH is a measure of acidity?

• An increased acidity near an enzyme can cause its shape to change.

• The enzyme could unravel and become totally ineffective.

Activators

• Sometimes you need an enzyme to work faster and your body creates an activator.

• Other times you might eat something that acts as an activator.

• Activators make enzymes work harder and faster.

Inhibitors• These are the opposite of

activators. • Inhibitors either slow down

or stop the activity of an enzyme.

• They often bond to the protein, changing the overall shape of the enzyme.

• Remember, when the shape changes, the enzyme will not work the same way.

• A nasty example of an inhibitor is snake venom or maybe nerve gas from World War I.

Type of nucleic acids

• DNA is just one type of nucleic acid.

• Some other types are RNA, mRNA, and tRNA.

• Nucleic acids are polymers made out of nucleotides.

Nucleotides

• A sugar molecule

• A phosphate group

• A nitrogenous base

A nitrogenous bases