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ENZYME
1. Structure and properties
2. Enzymes Classification
3. Activities
4. Enzyme Application
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STRUCTURE AND PROPERTIES
Enzyme = protein protein
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Hierarchical nature of protein
structure stucture
Primary structure(Amino acid sequence)
Secondary structure -helix, -sheet
Tertiary structure Three-dimensional structureformed by assembly
of secondary structures
Quaternary structure Structure formed by morethan one
polypeptide chains
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Catalyst- speeds up attainment of reaction
equilibrium CATALYST
Enzymatic reactions- 103to 1017faster than
the corresponding uncatalyzed reactions
Substrates- highly specific reactants forenzymes SPESIFICITY
Properties of enzymes
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Properties of enzymes (continued)
Stereospecificity- many enzymes act upon
only one stereoisomer of a substrate
STEREOSPESIFICITY
Reaction specificity - enzyme product yields
are essentially 100% (there is no formation of
wasteful byproducts)
Active site- where enzyme reactions take place
ACTIVE SITE
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Enzyme Nomenclature and Classification
Trivial named, based on existed ancient name;
Examples: trypsin, pepsin, ptyalin, papain
Systematic named, Based on the reaction theycatalyze, add suffix
-ase. Examples: urease acts on
urea, argininase on arginine, tyrosinase on tyrosine.
International Commission on Enzymesnamed, Enzymes are classified
into 6 classesbased on the kind of reaction they catalyze
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The Six Classes of Enzymes
1.Oxidoreductases(dehydrogenases)
2.Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases (synthetases)
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1.Oxidoreductases(dehydrogenases)
Catalyze oxidation-reduction reactions
EC 1.1.1.27
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2.Transferases
Catalyze group transfer reactions
EC 2.6.1.2
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3.Hydrolases
Catalyze hydrolysis reactions where water is
the acceptor of the transferred group
EC 3.6.1.1
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4. Lyases
Catalyze lysis of a substrate, generating adouble bond in a
nonhydrolytic, nonoxidative
elimination (Synthasescatalyze the addition to
a double bond, the reverse reaction of a lyase)
EC 4.1.1.1
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5. Isomerases
Catalyze isomerization reactions
EC 5.1.1.1
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6. Ligases (synthetases)
Catalyze ligation, or joining of two substrates
Require chemical energy (e.g. ATP)
EC 6.3.1.2
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