Explain the structure of enzymes and discuss their metabolic reactions.
Enzyme, a protein that catalyses a specific reaction. ‘Living cells contain thousands of different enzymes’ (Elliott, p.214), each of which catalyses (that is, accelerates without itself being changed) just one kind of reaction. In some of these reactions, small organic molecules such as amino acids, sugars, nucleotides, and lipids are broken down to provide energy for the cell. In other reactions, small molecules are built into complex macromolecules, such as proteins, DNA, RNA, and polysaccharides, or used to carry signals, or to control cell movements or gene expression. Enzyme-catalysed …show more content…
Some cells also contain enzyme inhibitors, known as anti-enzymes, which prevent the action of an enzyme upon a substrate.
Enzymes are classified into several broad categories, such as hydrolytic, oxidising, and reducing, depending on the type of reaction they control. Hydrolytic enzymes accelerate reactions in which a substance is broken down into simpler compounds through reaction with water molecules. Oxidising enzymes, known as oxidises, accelerate oxidation reactions; reducing enzymes speed up reduction reactions, in which oxygen is removed. Many other enzymes catalyse other types of reactions.
The different levels of protein structure are known as primary, secondary, tertiary, and quaternary structure. There are 20 common amino acids classified by their functional group, or their "R" group. When the weak hydrogen bonds that help the enzyme take its shape break because of the heat the enzymes have become denatured.
The primary structure is the sequence of amino acids that make up a polypeptide chain. 20 different amino acids are found in proteins. The exact order of the amino acids in a specific protein is the primary sequence for that protein.
Secondary structure - The amino acids form regular repeating patterns folding along the protein back bone. There are two common structures, the alpha helix and the beta pleated sheet.
In an alpha helix, ‘the