【精品】PPT课件 Chapter 16 Amino Acids, Proteins, and Enzymes.ppt

Chapter 16 Amino Acids, Proteins, and Enzymes
Enzymes
Enzyme Action
1
Enzymes are Biological Catalysts
Enzymes are proteins that
Catalyze nearly all the chemical reactions taking place in the cells of the body.
Increase the rate of reaction by lowering the energy of activation.
2
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 mon name, particularly for the digestion enzymes such as pepsin and trypsin.
Names of Enzymes
3
Enzymes are classified by the reaction they catalyze.
Class Type of Reactions catalyzed
Oxidoreductases Oxidation-reduction
Transferases Transfer groups of atoms
Hydrolases Hydrolysis
Lyases Add atoms/remove atoms to or
from a double bond
Isomerases Rearrange atoms
Ligases Use ATP bine small molecules
Classification of Enzymes
4
Match the type of reaction with an enzyme.
1) aminase 2) dehydrogenase
3) isomerase 4) synthetase
A. Converts a cis-fatty acid to a trans-fatty acid.
B. Removes 2 H atoms to form double bond.
C. Combines two molecules to make a pound.
D. Adds NH3.
Learning Check
5
Match the type of reaction with an enzyme
1) aminase 2) dehydrogenase
3) isomerase 4) synthetase
A. 3 Converts a cis-fatty acid to a trans-fatty acid.
B. 2 Removes 2 H atoms to form double bond.
C. bines two molecules to make a pound.
D. 1 Adds NH3.
Solution
6
The active site
is a region within an enzyme that fits the shape of the reacting molecule called a substrate.
contains amino acid R groups that bind the substrate.
releases products when the reaction plete.
Active Site
7
Enzyme Catalyzed Reaction
In an enzyme-catalyzed
reaction
a substrate attaches to the active site.
an enzyme-substrate (ES) complex forms.
reaction occurs and products are released.
an enzyme is used over and over.
E + S ES E + P
8
Lock and Key Model
In the lock