ENZYMES

ACTIVATION ENERGY

&

REACTION GRAPHS

ADDITIONAL GRAPHS &

PRACTICE PROBLEMS

An enzyme:

• is a protein

• is a biologic catalyst

• is very specific

• is not used up in a chemical reaction

• has an active site that its substrate binds to

• lowers the activation energy of a reaction

Enzymes

Enzymes

Types of Chemical Reactions

ENDERGONIC

• REACTIONS IN WHICH

THE ENERGY OF THE

PRODUCT(S) IS

GREATER THAN THE

ENERGY OF THE

REACTANTS

• THAT IS: ENERGY HAS

BEEN ABSORBED IN

THE REACTION

EXERGONIC

• REACTIONS IN WHICH

THE ENERGY OF THE

REACTANTSIS

GREATER THAN

ENERGY OF THE

PRODUCTS

• THAT IS: ENERGY HAS

BEEN RELEASED IN

THE REACTION

(don’t worry about ∆G in diagram below)

Endergonic & Exergonic Energy

Graphs

What is activation energy?

• It is the nrg necessary to get the reaction to go

forward (even if it is an exergonic reaction).

What is activation energy?

Enzymes Lower the Activation Energy

so the Reaction occurs faster & requires

less energy

• Red line in graph

represents how much

energy needed to get

from reactants

products

• Blue line represents

how much energy

needed when an enzyme

is present

Enzymes Lower the Activation Energy

so the Reaction occurs faster & requires

less energy

• The peak of the red line

(or blue line) coincides

with the point where the

bonds in the reactants of

the reaction are weakest.

It is also called a

transition state

• http://www.youtube.com/watch?v=VbIaK6PLrR

M

• http://www.stolaf.edu/people/giannini/flashani

mat/enzymes/transition%20state.swf

http://www.youtube.com/watch?v=VbIaK6PLrRMhttp://www.stolaf.edu/people/giannini/flashanimat/enzymes/transition state.swf