Proteins as enzymes
•There are 6 major classes of enzymes:
•    1.Oxidoreductases, which are involved in oxidation, reduction, and electron or proton transfer reactions;
•   2.Transferases, catalyzing reactions in which groups are transferred;
•   3.Hydrolases that cleave various covalent bonds by hydrolysis;
•   4.Lyases catalyze reactions forming or breaking double bonds;
•   5.Isomerases catalyze isomerization reactions;
•   6.Ligases join constituents together covalently.
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