Transcript enzymes - kristashunkwiler

Proteins
Structure:
Polypeptide chains
Consist of peptide bonds between 20
possible amino acid monomers
Have a 3 dimensional globular shape
Functions of Proteins
I. Structural materials, including keratin
(_____________________) and
collagen
(______________________________).
II.Binding, such as ________________
that bind specifically to foreign
substances to identify them to the
body's immune system.
III.Specific carriers,
________________________________
_______________________________,
and blood proteins, such as
hemoglobin, that carry oxygen, iron, and
other substances through the body.
IV. Contraction, such as
____________________ fibers that
interact in muscle tissue.
V. Signaling, including
_____________________ that regulate
sugar levels in blood.
VI. ENZYMES
Free Energy DG
• Energy is stored in bonds within
molecules
• There is also unavailable energy
present in the molecule that cannot be
used because it is energy of disorder
• Free energy is the energy that is
available energy
Types of reactions
• See Page 147 in Raven, Johnson
• If DG is negative, then there was free energy
released so the products of the reaction have
less energy than the reactants
= _____________________
• If DG is positive, then the products of the
reaction contain more energy than the
reactants and energy was absorbed
• = _____________________
Activation Energy
• All chemical reactions need energy to get
started = Activation Energy
• ____________________________________
____________________________________
• Higher temperatures can increase the
reaction rate, but too high can be dangerous
so…
• ____________________________________
____________________________________
____________
• Enzymes are specific, so there is a different
enzyme for each chemical reaction
Is this reaction exergonic or endergonic?
What are Enzymes?
• Catalysts change the rate of the
reaction without being altered
themselves.
• _____________________________.
• _______________________, whose
three dimensional shape allows for their
ability to react specifically.
Enzyme / Substrate
Relationship:
• What is the substrate?
• ____________________________________
____________________________________.
• Enzymes are substrate specific.
• ____________________________________
____________________________________.
• These principles lead to the “Induced Fit”
model of enzyme action.
The Active Site
• The active site is where
___________________________________
___________________________________.
• Most enzyme-substrate interactions are the
result of weak bonds.
• The active site may cause the enzyme to
hold onto the substrate in a very specific
way.
• The active site may provide a microenvironment
___________________________________
___________________________________
Rate of Reaction: Enzyme
Kinetics
I.
•
•
•
Time
Initially, substrate concentration is high =
________________________________
Eventually substrate concentration
decreases and
__________________________________
The enzyme has more products binding to
the active site
=
__________________________________
__________________________________
Feedback
Inhibition
Rate of Reaction: Enzyme
Kinetics
II.
•
•
Temperature
Up to 40oC, the reaction rate
increases because more heat = more
motion, collisions, more products
Above 40oC,
______________________________
______________________________
Rate of Reaction: Enzyme
Kinetics
III. pH
•
Different enzymes have
______________________________
•
Adding H+ to solution or removing H+
can __________________________
in the enzyme causing the enzyme to
unfold or denature
Enzyme Activity
• Temperature
• pH
• Enzyme
Concentration
• Substrate
Concentration
Rate of Reaction: Enzyme
Kinetics
IV. Cofactors/Coenzymes
• Non-protein molecules that help enzymes
function.
• Bind to active site to enhance enzymatic
reactions or can bind to the substrate.
• Cofactors may be inorganic metals such as
zinc, iron, or copper.
• Coenzymes are organic cofactors (e.g.
vitamins)
Rate of Reaction: Enzyme
Kinetics
V.
•
•
•
•
Free Radicals
Produced when our bodies undergo
aerobic respiration
Drug and alcohol use can increase free
radicals
Can cause enzymes to denature
Certain foods containing antioxidants can
reduce free radicals by accepting the H+
Enzyme Inhibition
• Competitive inhibitors ____________________________________
____________________________________.
Or, too much product can inhibit by binding to
the active site so reactants can’t bind.
• Non-competitive inhibitors bind to the enzyme
at sites called allosteric sites.
____________________________________
____________________________________,
and indirectly cause a change in the active
site.
Feedback
Inhibition
Allosteric Regulation
• Regulatory molecules that bind to the
enzyme’s allosteric site changing the shape
of the enzyme.
• Allosterically regulated enzymes have a
quaternary protein structure.
• Each subunit of the enzyme has an active
site and an allosteric site.
• Allosteric activators stabilizes the active site
• Allosteric inhibitors deactivates the active
site.