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Enzymes are biological catalysts Enzymes are proteins that: Increase the rate of reaction by...

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Page 1: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 2: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Enzymes are biological catalysts Enzymes are proteins that: Increase the rate of reaction by

lowering the energy of activation. Catalyze nearly all the chemical

reactions taking place in the cells of the body.

Have unique three-dimentional shapes that fit the shapes of reactants.

Page 3: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 4: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

The name of an enzyme : Usually ends in –ase. Identify the reacting substance. Ex: sucrase catalyzes the reaction of

sucrose. Describes the function of the enzyme. Ex: oxidases catalyze oxidation. Could be a common name , particularly

for the digestion enzymes such as pepsin and trypsin.

Page 5: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

ExamplesExamples

To react with lactoselactose.

lactlactaseaseTo remove carboxylcarboxyl from pyruvatepyruvate.

pyruvate pyruvate decarboxyldecarboxylasease

-ase-ase ending

whatwhat withwith orhowhow

it reacts+

Page 6: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

The active site: Is a region within an enzyme that

fits the shape of molecules called substrates.

Contains amino acid R groups that align and bind the substrate.

Release products when the reaction is complete.

Page 7: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 8: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

The proper fit of a substrate (S) in an active site forms an enzyme-substrate (ES) complex.

E + S ES Within the (ES) complex, the reaction occurs

to convert substrate to Product (P).

  ES E + P The products which are no longer attracted

to the active site, are released.  Overall substrate is converted to products.

E + S ES E + P

 

Page 9: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 10: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

animation

Page 11: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Enzymes may recognize and catalyze:

A single substrate. A group of similar substrates. A particular type of bond.

Page 12: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Classification of Enzymes

Enzymes are classified by the reaction they catalyze.Class Type of Reactions catalyzedOxidoreductases Oxidation-reductionTransferases Transfer groups of atomsHydrolases HydrolysisLyases Add atoms/remove atoms to or

from a double bondIsomerases Rearrange atomsLigases Use ATP to combine small molecules

Page 13: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Oxidoreductases and Transferases

Page 14: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Hydrolases and Lyases

Page 15: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Isomerases and Ligases

Page 16: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Isoenzymes

Catalyze the same reaction in different tissues in the body.

LDH, which converts Lactate to Pyrovate, have 5 isoenzymes.

Page 17: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Isoenzymes

Page 18: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Diagnostic Enzymes The levels of diagnostic enzymes determine the amount

of damage in tissues.

Page 19: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Diagnostic Enzymes

Levels of enzymes CK, LDH, and AST Are elevated following

a heart attack. Are used to determine

the severity of the attack.

Page 20: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 21: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 22: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Lock and key model In the lock and key model of

enzyme action: The active site have a rigid shape. Only substrates with the matching

shape can fit. The substrate is a key that fits the

lock of the active site.

Page 23: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 24: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Induced fit model In the induced fit model: The active site is flexible, not rigid. The shape of the enzyme active site

and substrate adjust to maximum the fit, which improve catalysis.

There is a greater range of substrate specificity.

Page 25: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.
Page 26: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Temperature. pH. Substrate concentration. Inhibitors.

Page 27: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

COMPETITIVE INHIBITION

Page 28: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

NON-COMPETITIVE INHIBITION

Page 29: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Classification of Enzymes• Oxidoreductases catalyze redox reactions

– Reductases

– Oxidases

• Transferases transfer a group from one molecule to another– Transaminases catalyze transfer of an amino group

– Kinases transfer a phosphate group

Page 30: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Classification of Enzymes

• Hydrolases cleave bonds by adding water

– Phosphatases– Peptidases – Lipases

• Lyases catalyze removal of groups to form double bonds or the reverse break double bonds

– Decarboxylases– Synthases

Page 31: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

Classification of Enzymes• Isomerases catalyze intramolecular

rearrangements – Epimerases – Mutases

• Ligases catalyze a reaction in which a C-C, C-S, C-O, or C-N bond is made or broken

Page 32: Enzymes are biological catalysts Enzymes are proteins that:  Increase the rate of reaction by lowering the energy of activation.  Catalyze nearly all.

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