Enzymes

1
Enzymes

• Protein molecules that act as catalysts

2
Catalysts

• Speed up the rate of reactions
• Are not permanently changed or used up
• Reactants what the catalysts change

• To the right is a Scanning Electron Microscope
  image of rutile crystals grown using Altair's
  process.

3
Jobs enzymes do

• Join monomers to make polymers
• Break down polymers
• Phosphorylate molecules
• Bring atoms together so they can trade electrons
• What kind of bonding is this?

• polypropylene can be widely found in items such
  as plastic bottles and boxes, dishwasher-safe
  food containers, patio furniture, rope,
  upholstery, diapers, and carpeting.
• It did not become commercially viable until a
  catalyst that increased its production could be
  found

4
(No Transcript)
5
Naming enzymes

• Depends on substrates and kinds of reactions
• Nearly all enzymes end in Ase
• Polycarbonate seen under a microscope

6
Activation energy

• Adding energy to a substance makes it more
  reactive
• For different reactions different energy
  thresholds are needed
• Enzymes lower that threshold

7
Enzyme substrate complexes

• Functional groups determine an enzymes shape
• The part the substrate binds to is the active
  site
• It looks like a pocket or groove
• This means that an enzyme is very specific

8
Helper molecules

• Some enzymes need to contain an additional
  molecule or ion to do their job
• Cofactors are helpers held on by ionic or other
  kinds of bonds
• Coenzymes are non-protein organic molecules
• Like vitamins
• They dont get used up so we dont need too many

9
Factors that effect enzyme activity

• Vmax this is the fastest number of substrates an
  enzyme can process
• Competitive inhibitors look like the enzymes
  substrate so they block up the active site
• More substrate can reduce their effects

10
Factors that effect enzyme activity

• Noncompetitive inhibitors effects dont reverse
• Cyanide, prevents Iron from doing its job in
  breathing
• Thats why its fatal

11
Allosteric enzymes

• Have 2 or more binding sites
• Binding to a regulatory site changes the shape of
  the inactive enzyme, either stimulating or
  inhibiting enzymatic reaction

12
from Drug Discovery Today 11 481-493 (2006)
13
statins Inhibitors of the enzyme HMG CoA
reductase The first enzyme in the pathway that
makes cholesterol
14
Metabolic syndrome

• a combination of medical disorders that increase
  one's risk for cardiovascular disease and
  diabetes.
• Leads to
• 1. Obesity, particularly around the waist (having
  an "apple shape")
• 2. Elevated blood pressure
• 3. An elevated level of triglycerides and a low
  level
• of high-density lipoprotein (HDL) the "good"
  cholesterol
• 4. Resistance to insulin

15
Complex interplay between glucose/fat/cholesterol
metabolism
16
Enzymes?

• Biological washing powders
• Drug targets
• Tests for disease/test kits
• Clinical tests for liver damage

17
Biological washing powders
Contain lipases and proteases to digest fat and
protein in stains Work at lower temperatures
18
Energy and Enzymes
Life requires energy.
Almost all energy for life is derived from the
sun.
A factoid -
The suns energy that strikes Earth each day is
equivalent to one million Hiroshima-sized atomic
bombs.
Photosynthesis harnesses about 1 of that energy
10,000 atomic bomb equivalents per day.
19
Chemistry and Life
One unromantic but productive way of viewing life
is to see it as a set of coordinated chemical
reactions.
This leads to an obvious question What
determines what chemical reactions are possible?
20
Chemical Reactions
Whether a chemical reaction will or wont occur
under particular conditions is determined by the
laws of thermodynamics.
Keeping it simple -
If the overall amount of order is decreased by a
reaction, the reaction is favored.
Generally, if energy is released in a reaction,
the reaction is favored.
21
The Direction of Spontaneous Reactions (and what
it takes to go the other way)
22
Life Requires Lots of Unfavorable Reactions How
Is This Possible?
favorable reactions
unfavorable reactions
23
The Nature of Life Coupling Favorable to
Unfavorable Reactions
24
ATP - Lifes Energy Currency
Energy is released when ATP is hydrolyzed
(broken down) to ADP.
ATP is restored from ADP and an input of energy.
ATPs energy is used to drive endergonic
(energy-requiring) reactions.
25
The Way ATP Often Works
26
Enzymes Speed Biochemical Reactions
Enzymes are biological catalysts substances
that speed a reaction without being altered in
the reaction.
Most enzymes are proteins, some are RNA.
Enzymes are essential for life.
27
Enzymes Lower a Reactions Activation Energy
28
Enzyme Action
29
The Fit Between Enzyme and Substrate is Critical
and Precise
30
Many Enzymes Work by Altering the Shape of Their
Substrates
The active site of an enzyme is where substrate
is bound.
31
Enzyme Deficiency and Health
Most genetic disorders are due to a deficiency in
enzyme function.
This archival photo shows three children with the
enzyme deficiency that causes phenylketonuria.
32
Metabolic Pathways
The synthesis of biological molecules often
requires many enzyme-catalyzed steps.
The entire set of steps is a metabolic pathway.
33
Metabolic Pathways
The metabolic pathway that produces tryptophan
an amino acid. This is one of hundreds of
metabolic pathways essential for life.
34
Enzyme Activity is Often Regulated
Feedback inhibition - a common form of enzyme
regulation in which the product inhibits the
enzyme .