BIOC 1303 Lecture Notes - Lecture 10: Pyridoxal Phosphate, Pyridoxal, Flavin Adenine Dinucleotide
28 Jun 2018
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Introduction to Organic and Biological Chemistry for Health Sciences
Chapter 20 Enzymes and Vitamins
20.1 Enzymes
Learning Goals → Describe how enzymes function as biological catalysts.
→ Name and classify them.
Enzymes are Biological Catalysts - pg 711
- Enzymes are proteins that increase the rate of reaction by lowering the
energy of activation.
- Enzymes catalyze nearly all the chemical reactions taking place in the
cells of the body.
- Enzymes have unique three dimensional shapes that fit the shapes of
reactants.
20.2 Enzyme Action
- The name of an enzyme usually ends in – ase.
- Identifies the reacting substance. For example, sucrase catalyzes the reaction of
sucrose.
- Describes the function of the enzyme. For example, oxidases catalyze oxidation.
- Could be a common name, particularly for the digestion enzymes such as pepsin and
trypsin.
Classification of Enzyme - Pg. 712
- Enzymes are classified according to the reaction they catalyze.
Class Reactions Catalysts
1. Oxidoreductase
2. Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases
Oxidation-reduction.
Transfer groups of atoms.
Hydrolysis.
Add atoms/remove atoms to/from a double bond.
Rearrange atoms.
Use ATP to combine molecules.
Enzyme Classification Summary 1: Oxidoreductases and Transferases
Enzyme Classification
Summary 2:
Hydrolases and Lyases
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- Pg. 712
Enzyme Classification
Summary 3: Isomerases and
Ligases - Pg. 712
20.1 Learning Check: Classification of Enzymes
20.2 Enzyme Action Learning Goal
Learning Goal → Describe the role of an enzyme in an enzyme-catalyzed reaction.
Active Site - Pg. 714
- Is a region within an enzyme that fits the shape of molecules called substrates.
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- Contains amino acid R groups that align and bind the substrate.
- Releases products when the reaction is complete.
Lock-and-Key Model - Pg. 715
→ In the lock-and-key model of enzyme action:
- The active site has a rigid shape.
- Only substrates with the matching shape can fit.
- The substrate is a key that fits the lock of the active site.
Induced-Fit Model - Pg. 715
→ In the induced-fit model of enzyme action:
- The active site is flexible , not rigid.
- The shapes of the enzyme, active site, and substrate adjust to
maximum the fit, which improves catalysis.
- There is a greater range of substrate specificity.
Enzyme Catalyzed Reaction - English
- 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 convert to product.
E + S ⇌ES → E + P
Diagnostic Enzymes - Pg. 716-717
- The levels of diagnostic enzymes determine the amount of damage in tissue.
Isoenzymes - Pg. 716
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Document Summary
Introduction to organic and biological chemistry for health sciences. Learning goals describe how enzymes function as biological catalysts. Enzymes are proteins that increase the rate of reaction by lowering the energy of activation. Enzymes catalyze nearly all the chemical reactions taking place in the cells of the body. Enzymes have unique three dimensional shapes that fit the shapes of reactants. The name of an enzyme usually ends in ase. For example, sucrase catalyzes the reaction of sucrose. Could be a common name, particularly for the digestion enzymes such as pepsin and trypsin. Enzymes are classified according to the reaction they catalyze. Learning goal describe the role of an enzyme in an enzyme-catalyzed reaction. 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. Releases products when the reaction is complete. In the lock-and-key model of enzyme action: Only substrates with the matching shape can fit.
