Transcript enzymes - Issaquah Connect

ENZYMES
Definition of Enzymes:
• A globular protein which
functions as a CATALYST.
Enzyme Animation
Location of Enzymes
• Protein molecules are produced by living cells.
• Each cell contains several hundred different
enzymes.
• They promote a vast number of rapid chemical
reactions between a temperature limit suitable
for the particular organism
– About 5-40oC
• Without these catalysts, we would have to heat
up organisms to a point that is lethal or the
reaction would be too slow to sustain life.
Enzyme is a Catalyst
A catalyst is a substance that speeds up a chemical
reaction without being used up in the reaction.
In Short
• Enzymes make reaction happen faster at lower
temperatures
• Reactions that include thinking, breathing, heart
beat, eating, walking…
Some helpful terminology:
• SUBSTRATE: The substance (reactants) that an
enzyme acts on and makes more reactive. This
could be another protein, lipid, carbo. or nucleic
acid.
– Ex. Lactase (enzyme) that acts on lactose (substrate)
ACTIVE SITE:
• The area of an enzyme molecule which binds
to the substrate.
– Groove in enzyme surface, formed with only a few
of its amino acids.
Draw the active site
“Lock and Key”
• Enzyme specificity is based on
compatible fit between shape of
active site and shape of
substrate.
– The substrate is the key whose
shape is complementary to the
enzyme or lock.
“Lock and Key”…Specificity
• A different substrate would need a
different “Lock” …enzyme!
•This is called
SPECIFICITY!
Example
• Starch which is then broken down into maltose
(a disaccharide) parts by the enzyme amylase.
Amylase
Starch

Maltose
(amylase is the enzyme in saliva)
• To break maltose into glucose, a different
enzyme is needed…maltase.
Maltose
Maltase

Glucose
• Enzymes do not actually change in the
reaction.
– They leave the reaction unaltered.
RATE OF REACTION:
The time it takes to break down a given amount of
substrate into a given amount of product.
Example:
–The more enzyme present, the faster the
substrate will be broken down.
POISONS:
•Mercury and Lead
–-these cause enzyme molecules
to clump together so they
become useless (inactive)
THE WHOLE ENZYME
STRUCTURE:
• Most of it is made of protein.
– They also need a non-protein part
to work
THE WHOLE ENZYME
STRUCTURE:
• Non-Proteins such as minerals like
– Iron
– Magnesium
– Vitamins
• These are needed to make the correct
attachment (active site) so that the enzyme
can do its job.
– This is one of the reasons we need to have
certain vitamins and minerals in our diet.
Denaturation:
• Loss of the 3-D shape of a protein (it unravels).
– This destroys the active site
– Caused by: Heat, Cold, Chemical agents, pH change
(too acidic or basic)
• This is why a temp. of over 104° F is dangerous and person
should go to the hospital.
Denaturation: causal agents
• Heat:
Irreversible
– ex. Cooked
egg
– Agitates the
polypeptide
chain
enough to
over power
the weak
interactions.
Ohhh, the cold water is denaturing
my enzymes and starting to destroy
their 3D globular shape resulting in
their loss of a proper active site.
Help, Help I’m denaturing!!!!!