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EnzymesEnzymes

• Brief introductory enzyme video:• https://www.youtube.com/watch?v=vTQybDgweiE • Goofy video on how enzymes work:• https://www.youtube.com/watch?v=XTUm-75-PL4

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What Are Enzymes?What Are Enzymes?• Most enzymes

are Proteins Proteins ((tertiary and quaternary structures)

• Act as CatalystCatalyst to accelerate a reaction

• 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

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How do enzymes Work?How do enzymes Work?

Enzymes work by lowering lowering activation activation energy which energy which speeds up a speeds up a reactionreaction

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EnzymesEnzymes

FreeEnergy

Progress of the reaction

Reactants

Products

Free energy of activationFree energy of activation

Without Enzyme

With Enzyme

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Enzyme-Substrate ComplexEnzyme-Substrate ComplexThe 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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Induced FitInduced Fit

• A changechange in the configurationconfiguration of an enzyme’s activeenzyme’s active site site (H+ and ionic bonds are involved).

• InducedInduced by the substratesubstrate..

Enzyme

Active Sitesubstrate

induced fit

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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 are the most dangerousmost dangerous

- - high tempshigh temps may denature denature (unfold) (unfold) the enzyme. enzyme.

2.2. pHpH (most like 6 - 8 pH near (most like 6 - 8 pH near neutral)neutral)

3.3. Ionic concentrationIonic concentration (salt (salt ions)ions)

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2. Cofactors and Coenzymes2. Cofactors and Coenzymes

Inorganic substances Inorganic substances (zinc, iron)(zinc, iron) and vitaminsvitamins (respectively) 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 up oxygen.pick up oxygen.

Other enzymes Other enzymes areare s sometimes needed to activate another enzyme.

Our food is made up of:• Carbohydrates: Bread, Pasta, Potato• Protein: Meat, Nuts, Lentils• Fats: Butter, Milk

Our body needs to digest them – turn them into a form that can be absorbed into the blood and used by cells. Enzymes make this possible.

Enzyme video/animation: https://www.youtube.com/watch?v=r1ryDVgx0zw

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Enzymes that work on carbohydrates:

Salivary Amylase + Starch Maltose (in saliva) (in pasta, bread (a form of sugar that

carbohydrate) can be absorbed by the body )

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Enzymes that work on Proteins:

Protease + Proteins Amino Acids (in stomach) (eg. In meat, nuts) (the body can absorb

them and use them)

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Enzymes that work on Fats:

Lipase + Fats Fatty Acids + Glycerol (secreted by pancreas) (Butter, Milk) (can be

absorbed into body)

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