Introduction
Enzymes are biological catalysts. Catalysts are substances that increase the rate of chemical reactions without being used up themselves. Enzymes are also proteins. They all have different and complex shapes that allow smaller molecules to fit into them. The place where these substrate molecules fit is called the active site. The shape of an enzyme can change; its active site may no longer work. It is said the enzyme is denatured. They can be denatured by high temperatures or extremes of pH.
Like all other proteins, enzymes are made of amino acids. Each enzyme is made of between 100 to 1 million amino acids placed like pearls on a string. Each amino acid is bonded to the next by chemical bonds. Some enzymes can be made from 20 different kinds of amino acids. No two enzymes are alike. Each enzyme has its own unique sequence of amino acids, which is determined by the genes in the cells.
Enzymes consist of millions of amino acids placed one after the other, however, do not look like a long string of amino acids. In most enzymes the string is coiled and folded thousands of times to form a highly complex three-dimensional structure. It is the chemical interactions between the amino acids that force the enzymes into their three-dimensional structure, which is held together by the many different links between the different amino acids. Each enzyme has its own unique three-dimensional structure that determines the function of the enzyme. The three-dimensional structure of enzymes is determined by the order of the amino acids. Even slight changes of the sequence of amino acids will have a big impact on the structure of the protein. An enzyme may not only look different, but also act different. With only a slight change in the sequence of the amino acids, an enzyme may be converted into working on other biological molecules or treating them differently.
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