State and describe the roles of the six classes of enzymes, giving three examples each

Human Biology (MindTap Course List)
11th Edition
ISBN:9781305112100
Author:Cecie Starr, Beverly McMillan
Publisher:Cecie Starr, Beverly McMillan
Chapter3: Cells And How They Work
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State and describe the roles of the six classes of enzymes, giving three examples each

Expert Solution
Introduction

Enzymes are essential proteins prepared and required by the cell to catalyze various metabolic reactions. They act by lowering the activation energy of the reaction so that the reactions that are otherwise impossible to take place or have a very slow rate in normal conditions could be carried out easily. As almost all the biochemical reactions in the living systems are catalyzed by enzymes, they are crucial for survival.

Explanation

Enzymes are biomolecules that speed up or catalyze the reactions taking place in biological systems. There are more than 1000 different enzymes present in humans. They are classified into six different categories based on their roles.

1. Oxidoreductases: These enzymes catalyze the reactions that involve the oxidation-reduction process. They transfer the electron in the form of hydride ions or hydrogen from the donor molecules or reductants to the acceptor molecules or oxidants. Peroxidases, oxygenases, and hydroxylases belong to the group of oxidoreductases. 

2. Transferases: The enzymes that catalyze the reactions involving the transfer of a functional group from one molecule to another are known as transferases. Most of the transfer requires cofactors to function. Transaminases, kinases, and acetyltransferases belong to this group.

3. Hydrolases: These group of enzymes carries out hydrolysis of the various complex biomolecules by cleaving the covalent bonds and transferring functional group to water. It is a digestive enzyme. Proteases, lipases, and nucleases are hydrolases.

4. Lyases: These are the enzymes that catalyze the addition or elimination reactions of a functional group. Lyases do not need water for split reactions. Decarboxylases, dehydratases, and aldolases belong to this group.

5. Isomerases: The enzymes responsible for intramolecular structural rearrangements are known as isomerases. They convert one isomer to the other by breaking and forming the bonds in the molecule in a way that molecule has the same molecular formula but different geometrical structure. Mutases, racemases, and epimerases belong to this group.

6. Ligases: The enzymes that join two molecules using ATP and forming a new bond between them are known as ligases. The two substrates involve are usually large biomolecules. They are also known as synthetase as they are involved in the process of synthesis. Amide synthetases, argininosuccinate synthetase, and peptide synthetases.

Translocases are also one group of enzymes that is responsible for the translocation of molecules or ions across the cell membrane.

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ISBN:
9781305112100
Author:
Cecie Starr, Beverly McMillan
Publisher:
Cengage Learning