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Enzymes . What are they?. Organic/Biological Catalysts Proteins Reusable There’s over 40,000 found in humans Usually end in the suffix – ase Named after what it “eats” (ex: if an enzyme is meant to eat lact ose the enzyme is lact ase ). How do they work?.

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Presentation Transcript
what are they
What are they?
  • Organic/Biological Catalysts
  • Proteins
  • Reusable
  • There’s over 40,000 found in humans
  • Usually end in the suffix –ase
  • Named after what it “eats” (ex: if an enzyme is meant to eat lactose the enzyme is lactase)
how do they work
How do they work?
  • Enzymes possess an active site (which is like a cleft in the molecule)
  • The active site is where its food (substrate) goes into
  • When the substrate binds to the enzyme it is called an enzyme substrate complex
  • A new substrate will then be synthesized (created) or the old one will be split
  • Enzymes DO NOT change in the process
reactions
Reactions
  • Enzymes CANNOT create reactions they only speed them up
  • Enzymes speed up reactions by lowering the activation energy (energy needed to get the reaction to take place)
  • There are two parts to a chemical reaction: reactants (what goes in) and products (what comes out)
  • Example: Carbonic anhydrase is an enzyme found in RBCs where it catalyzes the reaction CO2 + H2O ↔ H+ + HCO3− this allows blood to transport CO2 from the tissues to the lungs (one molecule of this enzyme can process one million molecules of CO2 each second
slide8

Enzymes

Specific

Properties

Increase rate of the reaction

Unchanged at the end of the reaction

Reactions too slow to maintain life

Need them

Can’t increase temperatures/pressure in cells (fatal)

molecule geometry
Molecule Geometry
  • Substrate molecule fits into the enzyme like a lock & key.
  • Enzyme shape distorts or changes other factors to make the reaction happen
  • However certain substances canbind to the enzyme at sites other than the active site and modify its activity (inhibitors/co-factors)
  • Idea that the enzyme is flexible (induced fit)
activation energy
Activation Energy
  • In a ‘natural’ reaction the product has a lower energy than the substrate so equilibrium will take it in the direction of the product.
  • However there is an energy ‘barrier’ to be overcome
  • Enzymes lower the activation energy required to bring about a reaction.
  • Activation energy- the minimum amount of energy needed to start a reaction
slide11

High energy

intermediate

Activation energy

Energy

Substrates

Products

Progress of reaction

slide12

Enzyme activity

Temperature

pH

Four Variables

Enzyme Concentration

Substrate Concentration

optimum condition
Optimum Condition

Enzymes function best or are most active in specific conditions known as optimum

conditions.

slide14

Temperature

5- 40oC

Increase in Activity

40oC - denatures

Rate of Reaction

0

10

20

30

40

50

60

<5oC - inactive

slide15

pH

Narrow pH optima

Disrupt Ionic bonds - Structure

Rate of Reaction

Effect charged residues at active

site

1

5

7

8

9

2

3

4

6

slide16

Enzyme Concentration

Rate of Reaction

Enzyme Concentration

slide17

Substrate Concentration

Active sites full- maximum turnover

Rate of Reaction

Substrate Concentration