Tuesday, 8/27

•Enzyme Notes•BIO WQ•Check Water WS and Bio WQ•Work on and check SG•Test tomorrow!

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EnzymesEnzymes

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What Are Enzymes?What Are Enzymes?

• Enzymes are Proteins that act as a Catalyst to accelerate a chemical reaction.

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EnzymesEnzymes• Enzymes are

specific for certain substance. (They are made for a specific chemical)

• They are reusable!

• Their names end is Their names end is –ase. Example: –ase. Example: Lactase Lactase

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How do enzymes Work?How do enzymes Work?

Enzymes work by weakening bonds and lowering the activation energy of a reaction.

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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

or reactant chemical the enzyme works on is called the substrate.

EnzymeSubstrate

Joins

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Active SiteActive Site• The substrate bonds to the active

site of the enzyme.

EnzymeSubstrate

Active Site

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Enzyme ActivityEnzyme Activity•Once the substrate bonds, the enzyme changes shape to induce the reaction

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Enzyme ActivityEnzyme Activity

• The substrate is chemically changed then released, and the enzyme returns to normal. It can now move on to a new substrate.

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. Extreme temperatures can 1. Extreme temperatures can damage or denature enzymesdamage or denature enzymes

2.2. Strong changes in pH (in either direction) can also denature enzymes

3.3. Too many ions (salts) can also denature enzymes.

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2. Cofactors and Coenzymes2. Cofactors and Coenzymes

• Inorganic substances Inorganic substances (zinc, iron)(zinc, iron) and vitaminsvitamins 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. Without Iron, it doesn’t work.

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Enzyme InhibitorsEnzyme Inhibitors

a. a. Inhibitors:Inhibitors: chemicals that pretend to be the enzyme’s substrate (but won’t react) or bond to the enzyme at a different point to “shut it off” keep enzymes from working until needed.

Enzyme

Competitive inhibitor

Substrate