enzymes structrure and functions

2.  Life requires energy.
 Almost all energy for life is derived from the sun.
 Living Things undergo many thousand of Chemical
Reactions as part of their life process.
 In a Chemical Reaction, Bonds present in the
Reactants are Broken. The Elements are
Rearranged, and NEW Compounds are formed as
the Products.
 Much of the Energy our body need is provided by
Sugars from Food.
 Body undergoes a series of Chemical Reactions in
which Sugars are broken down to Carbon Dioxide
and Water. In this process, energy is released for
use by the body.

3.  Chemical Reaction that involve a Net Release of Free
Energy are called EXERGONIC REACTIONS.
 Reactions that involve a Net Absorption of Free
energy are called ENDERGONIC REACTIONS.
 For most Chemical Reactions to begin, Energy Must
Be Added to the Reactants.
 In many Chemical Reactions, the amount of Energy
NEEDED to START the Reaction, called ACTIVATION
ENERGY, IS HIGH.

4. Certain Chemical Substances, known as CATALYSTS, Reduce
the amount of Activation energy Needed. A Reaction in the
presence of a Catalyst will proceed Spontaneously or with the
addition of a small amount of Energy.

5. Enzymes
• What Are Enzymes?
• Enzymes are biological catalysts – substances that
speed a reaction without being altered in the reaction.
• Enzymes are specific for one particular reaction or
group of related reactions.
• Enzymes increases the rate of reaction.
• Enzymes are usually proteins. Enzymes possess
tertiary and sometimes quaternary structure.
Hydrogen bonding, disulfide bridges, hydrophobic
interactions, and ionic interactions hold the enzymes
in its conformation.

8.  All Enzymes are proteins.
 They have a globular shape.
 Enzymes are specific to their
substrates
 The specificity is determined
by the active site A complex 3-D structure
Human pancreatic amylase

12. Some proteins can change their shape (conformation)
When a substrate combines with an enzyme, it induces
a change in the enzyme’s conformation.
The active site is then moulded into a precise
conformation making the chemical environment suitable
for the reaction.

14. Cofactors
 An additional non-protein molecule that is needed by
some enzymes to help the reaction
 Tightly bound.
 Cofactors that are bound and released easily are
called coenzymes.
 Many vitamins are coenzymes.

16. Factors affecting Enzymes
 substrate concentration
 pH
 temperature
 inhibitors

17. Substrate concentration: Enzymic reactions
 Faster reaction but it reaches a saturation point
when all the enzyme molecules are occupied.
Reaction
velocity
Substrate concentration
Vmax

19. Inhibitors
 Inhibitors are chemicals that reduce the
rate of enzymic reactions.
 The are usually specific and they work at
low concentrations.
 They block the enzyme but they do not
usually destroy it.