Unformatted text preview: Enzymes 1 What Are Enzymes? • Most enzymes are
• Act as Catalyst to
• Not permanently
changed in the
process 2 Enzymes • Are specific for
what they will
• Are Reusable
• End in –ase
-Maltase 3 How do enzymes Work?
Enzymes work by
energy 4 Enzymes
With Enzyme Free
Energy Free energy of activation
Reactants Products Progress of the reaction
5 6 Enzyme-Substrate Complex
The substance (reactant) an enzyme acts on is the substrate
Substrate Joins Enzyme 7 Active Site
• A restricted region of an enzyme molecule which binds to the substrate.
Substrate Enzyme 8 Induced Fit • A change in the
shape of an
• Induced by the
substrate 9 Induced Fit
• A change in the configuration of an
enzyme’s active site (H+ and ionic
bonds are involved).
• Induced by the substrate.
substrate substrate Active Site
Enzyme induced fit
10 What Affects Enzyme Activity?
• Three factors:
1. Environmental Conditions
2. Cofactors and Coenzymes
3. Enzyme Inhibitors 11 1. Environmental Conditions
1. Extreme Temperature are the most
- high temps may denature (unfold) the
2. pH (most like 6 - 8 pH near neutral)
3. Ionic concentration (salt ions) 12 2. Cofactors and Coenzymes
• Inorganic substances (zinc, iron) and
vitamins (respectively) are sometimes need
for proper enzymatic activity.
Iron must be present in the quaternary
structure - hemoglobin in order for it to
up pick 13 Two examples of Enzyme
a. Competitive inhibitors: are
a. Competitive chemicals that resemble an
enzyme’s normal substrate and
compete with it for the active site.
Substrate Enzyme Competitive inhibitor 14 Inhibitors
b. Noncompetitive inhibitors:
Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site.
altered Enzyme Noncompetitiv
Inhibitor 15 16 ...
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