3.1 Enzyme Structure

Introduction

Enzymes are biological catalysts that speed up biochemical reactions without being consumed. They are essential for life because almost all chemical reactions in cells require enzymes. Understanding enzyme structure is fundamental to understanding how enzymes work.

Definition

Enzymes: Enzymes are biological polymers that catalyse biochemical reactions.

In simple words: Enzymes are biological molecules (usually proteins) that speed up chemical reactions in living organisms.

Core Concept

• There is complete check and balance on the chemistry of the cell.
• This is exhibited through various enzymatic reactions going on within a cell.
• The sum of all the chemical reactions going on in a cell is known as metabolism.
• These reactions have to be carried out very quickly so that their products can be utilized in various life activities in the cells.
• Enzymes are biological catalysts and therefore they speed up the biochemical reaction without being consumed.
• The enzymes exist in the cell as colloids.

Detailed Explanation

Historical Background

Science Tidbits (from textbook):

During the early nineteenth century, two French chemists, Payen and Persoz, grounded up barley seeds in water to make a crude mixture that would digest starch. They gave the name diastase to whatever it was that digested the starch.

Note: Diastase was the first enzyme discovered. It is now known as amylase.

Definition of Enzymes

We can define enzymes as:

"Biological polymers that catalyse biochemical reactions."

Structure of Enzymes

1. All enzymes are globular proteins which are made up of one or more polypeptides.

2. Ribozymes are the only exception which consist of RNA and are found in ribosomes. - For example, peptidyl transferase is a ribozyme which forms peptide bonds during protein synthesis.

3. The enzyme consists of a linear chain of amino acids, which form the three-dimensional structure of an enzyme.