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EnzymesEnzymes
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• A material that speeds up a chemical reaction or makes it possible. But, it does NOT become part of the reaction’s end product.
What’s a Catalyst?What’s a Catalyst?
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How is this important to
life?
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What Are Enzymes?What Are Enzymes?• Most enzymes are
Proteins Proteins ((tertiary and quaternary structures)
• Act as CatalystCatalyst• Not permanentlyNot permanently
changed in the process
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EnzymesEnzymes• Are specific for
what they will catalyzecatalyze
• Are ReusableReusable• End in –asease
-Sucrase-Sucrase-Lactase-Lactase-Maltase-Maltase
-Salivary Amylase-Salivary Amylase
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Enzyme-Substrate ComplexEnzyme-Substrate Complex
The substancesubstance (reactant) an enzymeenzyme acts on is the substratesubstrate
EnzymeSubstrate Joins
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Active SiteActive Site• A restricted regionrestricted region of an enzymeenzyme
molecule which bindsbinds to the substratesubstrate.
EnzymeSubstrate
Active Site
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Induced FitInduced Fit• A change in the
shapeshape of an enzyme’s active site
• Induced Induced by the substrate
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What Affects Enzyme Activity?What Affects Enzyme Activity?
• Three factors:Three factors:1.1. Environmental ConditionsEnvironmental Conditions
2.2. Cofactors and CoenzymesCofactors and Coenzymes
3.3. Enzyme InhibitorsEnzyme Inhibitors
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1. Environmental Conditions1. Environmental Conditions 1. Extreme1. Extreme Temperature Temperature are the most are the most
dangerousdangerous
2.2. pHpH (most like 6 - 8 pH near (most like 6 - 8 pH near neutral)neutral)
3.3. Ionic concentrationIonic concentration (salt ions) (salt ions)
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2. Cofactors* and Coenzymes**2. Cofactors* and Coenzymes**
• Inorganic substances* Inorganic substances* (zinc, iron)(zinc, iron) and vitamins**vitamins** are sometimes needed for proper enzymatic activityenzymatic activity.
• Example:Example:IronIron must be present in the quaternary quaternary
structurestructure -- hemoglobinhemoglobin in order for it to pick pick up oxygen.up oxygen.
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a. a. Competitive inhibitorsCompetitive inhibitors:: are chemicals that resembleresemble an enzyme’s normal substrateenzyme’s normal substrate and competecompete with it for the active siteactive site.
Enzyme
Competitive inhibitor
Substrate
3. Enzyme Inhibitors3. Enzyme Inhibitors
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b.b. Noncompetitive inhibitorsNoncompetitive inhibitors::Inhibitors that do not enter thedo not enter the
active siteactive site, but bind tobind to another partanother part of the enzymeenzyme causing the enzymeenzyme to change its shapechange its shape, which in turn
alters the active sitealters the active site.
Enzymeactive site altered
NoncompetitiveInhibitor
Substrate
Enzyme InhibitorsEnzyme Inhibitors
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How do enzymes Work?How do enzymes Work?
Enzymes work by weakening weakening bondsbonds which which lowers activation lowers activation energy.energy.