Enzymes€¦ · 4) Enzymes lower activation energy & speed up reactions by: • acting as...

Enzymes

Learning Goals• Understand how enzymes do and how they

function

• Understand factors affecting enzyme activity

What is an Enzyme?•

Lock and Key Model• Enzymes are specific to their substrate(s)

Enzyme-Substrate Complex• Substrates bind to an active site

Forms an

• Active site undergoes a

to better accommodate the substrate

Why Enzymes?• Heat usually speeds up reactions.

•

Enzyme Energy Profile

Enzyme Energy Profile

An

abo

lic

Rea

ctio

ns 1) Substrate binds to active site

2) Enzyme changes shape to

“embrace” substrate (Induced Fit)3) Substrates held in active

site by weak interactions:

- H-bonds

- Ionic bonds

4) Enzymes lower

activation energy &

speed up reactions by:

• acting as template for

substrate orientation

• Stressing substrate &

stabilizing transition

state

• Providing favorable

microenvironment

• Participating in

catalytic reaction

5) Substrates converted into products6) Products are

released

7) Active

site

available

again

Cat

abo

lic

Rea

ctio

ns

ATP ADP + Pi

ENZYME(ATPase)

Factors that Affect Enzyme Activity

Factors that Affect Enzyme Activity

Enzyme Cofactors• Activate enzyme/protein

• Coenzyme -

Allosteric Regulation

Competitive Inhibitors

Fee

db

ack

In

hib

itio

n

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