Chemical Reactions and Enzymes

I. What are enzymes?

Y

our body has lots of reactions!

E

nzymes: special protein catalysts that speed

up specific reactions

E

nd in ASE • Ex. Lactase digest lactose

Activation Energy:The energy needed to get a reaction started

III. Lower the Activation Energy

• Activation energy is

the “start up” energy of a reaction

• They do not raise the temp!

• Increase the frequency that the reactants come together to react!

FreeEnergy

Progress of the reaction

Reactants

Products

Free energy of activationFree energy of activation

Without Enzyme

With Enzyme

EnzymesEnzymes

IV. Enzymes are Specific

The shape of each enzyme fits the

shape of what its acting on

SUBSTRATE:

the reactant that connects with

enzyme

ACTIVE SITE:

area where the substrate and

enzyme meet up

V. Lock and key model

L

ock is the enzyme

K

ey is the substrate

T

he lock hole is the

active site

Enzymes can only catalyze 1 reaction because they only

allow substrates with one particular shape to bond

oes not fit!

Factors that Affect the Enzyme Performance

Temperature

pH

Salinity

Concentration of enzyme or substrate

TemperatureE

nzymes are PROTEIN

H

eat too high they can denature

Enzymes work best at

an ‘optimal’ pH

Proteins they can

denature

pH

SalinityT

oo much salt will cause the enzyme

(protein) to denature, changing its shape

so it will

not function

Other factors

C

oncentration of enzyme and concentration of

substrate will affect how many reactions can

occur.

R

eactions depend on the limiting factor!

Enzymes are Reusable

Enzymes will speed the

reaction for a substrate

It will release the

product and will work on

another substrate

Examples L

ipase

P

rotease

L

actase

S

ucrase

A

mylase

L

ife is not possible without enzymes! !!!!!!!