EnzymesObjective: Identify and understand the role

of enzymes

Chemical Reactions

• A chemical reaction is when bonds are broken and reformed to make different substances.

Reactant/Substrates Products

Ex. C6H12O6 + 6O2 6CO2 + 6H2O

glucose oxygen carbon dioxide water

Role of Enzymes• Increase biochemical reaction

rates• Help regulate cell metabolism

Enzymes

Characteristics of Enzymes:• Name usually ends in suffix –ase,

often derived from name of substrate– Maltase – enzyme that helps split

maltose

What enzyme splits sucrose?______________What enzyme splits lactose?_______________

Enzymes

• Bind to specific substrate(s)• Able to facilitate the reaction of

large quantities of substrate• Enable cell reactions to proceed at

biological temperatures• Work best at certain temperatures

and pH

Enzymes

Enzyme – protein that acts as a biological catalyst

Catalyst – substance that affects a chemical reaction without being used up themselves

Enzymes

Active site – location on the enzyme where reaction occurs

Substrate – substance that an enzyme acts upon

Product – substance that is created

Enzymes

Activation EnergyHow could you speed up this chemical reaction?

Ener

gy a

bsor

bed

Activ

ation

ene

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Reactant

Products

Ene

rgy

rele

ased

Activation EnergyLowering the activation

energy will speed up the reaction En

ergy

abs

orbe

dEn

ergy

rele

ased

Reactant

Products

Activation energy

Activation energy - the minimum energy needed to cause a chemical reaction to occur

Enzymes lower the activation energy!!!!

How Enzymes Work

Two theories of how enzymes bind to substrates• Lock-and-Key Model – substrate molecule

fits into enzyme just like a key fits into a lock

• Induced Fit Model – enzyme’s shape changes slightly to bind with substrate – More widely accepted

How Enzymes Work

• Substrate molecule fits into active site on enzyme– “Enzyme-substrate complex”

• Enzyme shape changes slightly to bind to substrate– “Induced fit”

• Enzyme catalyzes a chemical reaction in the substrate – Involves breaking or forming chemical bonds

• Products are released• Enzyme is ready to bind to another substrate

E + S ES E + P

How Enzymes Work-Order of Business

Enzyme

Active siteSubstrate

Product

Sucrose Glucose + Fructose sucrase

Enzymatic Reaction

Enzyme Substrate Complex