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 =
trypsin and peptidases
pepsin,
• 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