Enzymes

1
Enzymes
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2
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• Reaction accelerators
• 1,000,000 to 100,000,000 times increase
• Fly from NYC to LA in 1/100 of a second
• Build Hoover Dam in 30 seconds

3
Famous Enzyme Chemists
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• Pasteur First scientist to study
  enzyme-catalyzed reactions. "Fermentations"
• Buchner Ground yeast cells and made a cell-free
  media proving that living cells were not
  necessary for enzyme activity.

4
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• Enzymes are essential for life, reactions are
  normally too slow.
• Types of enzymes
• a. Simple polypeptides
• b. Complex polypeptides
• (1) Co-factors proteins and coenzymes
• (2) Trace elements Mn2, Mg2, Fe2
• c. RNA

5
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• Enzymes are LARGE
• Substrates are small
• active site

6
Enzyme Nomenclature
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• Oxidoreductases
• Transferases
• Hydrolases
• Lyases
• Isomerases
• Ligases
• EC 1.2.3.4 an oxidoreductase

7
Specificity
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• Lock and Key
• Induced Fit
• Stereospecificity chiral molecules

8
Enzymes and Temperature
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9
Enzymes and pH
0
10
Enzyme Mechanism

• Michaelis constant, KM
• Strength of attraction between enzyme and
  substrate
• Pick up oranges with left hand and peel them with
  right hand
• Maximum velocity, Vmax
• Maximum speed of the reaction
• Put orange down and pick up a new one

11
Enzyme Regulation
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• Inhibition (Reversible and Irreversible)
• Competitive
• Compete for active site, affects KM
• Add plastic balls to the bin of oranges
• Non-competitive
• Alters enzyme at site other than active
• Changes Vmax
• Put glove on right hand, slows peeling rate

12

• Allosteric enzymes binding of substrate to one
  domain affects the binding to other parts of a
  quaternary structure
• Positive and negative effectors
• Feedback and feedforward control
• Zymogens
• pepsinogen pepsin
• chymotrypsinogen chymotrypsin

13
Medical Enzymes
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• Certain enzymes are in high concentration in
  certain organs. When cell damage happens in that
  organ, the enzymes are leaked into the blood. By
  testing the blood for the presence of these
  enzymes, diseases can be detected quickly and
  accurately.

14
Creatinine phosphokinase EC 2.7.3.2
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• Present in skeletal muscle, cardiac muscle and
  brain tissue. This enzyme has two polypeptide
  chains M and B
• Isozymes
• CPK1 (BB) brain tissue
• CPK2 (MB) myocardium
• CPK3 (MM) skeletal muscle

15
Lactate dehydrogenaseEC 1.1.1.27
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• Present in most cells, cardiac muscle has only
  two of the isozymes. This enzyme has four
  polypeptide chains composed of H's and M's
• Isozymes
• LDH1 (HHHH)
• LDH2 (HHHM)
• LDH3 (HHMM)
• LDH4 (HMMM)
• LDH5 (MMMM)

16
Prostatic Acid PhosphataseEC 3.1.3.2
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• Produced in the prostate, PAP is present in
  semen. It is frequently used as a preliminary
  test for the identification of seminal material
  in rape cases.
• A test for PAP is to place the material into
  phenylphosphate, allow the enzyme to remove the
  phosphate group and then test for the phenol that
  remains with FeCl3 which produces a purple color.

17
0
Clear solution turns purple when FeCl3 is added
in the presence of the phenol.
18

• End of
• Chapter 22