Cells

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Enzyme Structure

Enzymes are essentially chains of amino acids that fold to form a unique shape specific to their function.

An enzyme is a biological catalyst. What do catalysts do?

Enzymes are able to perform their function in catalysing reactions because of their physical shape.

All enzymes are types of proteins, just like other biological structures, for example muscle fibres. So what do we call the building blocks of enzymes?

The order (sequence) of the amino acids in a protein is controlled by a single gene. This unique sequence gives the protein its unique properties.

All enzymes, gain their physical and chemical properties from the sequence of the amino acids that make up their long chains.

They are all made from a mixture of 22 naturally occurring amino acids! Enzymes do not have to use all 22 amino acids. A single chain may be thousands of amino acids long.

Looking at the two simplified enzymes in the example above, what is different about them?

A) The types of amino acids used B) The sequence of amino acids C) Type of chemical produced

Enzymes and other proteins don't differ in terms of which amino acids they employ in their chains. However, they do differ in the sequence of these amino acids, and they differ in the shape that that chain ultimately takes when it twists and folds.

This shows an enzyme

Internal forces have twisted and folded the protein strand into a unique shape that allows the enzyme to perform its unique function.

The internal forces that cause a protein strand to twist and fold are caused by each amino acid producing a small push or pull on the molecules around it. This folds the chain to make the final shape of the enzyme. If the amino acids were linked together in the wrong sequence, would that be a problem?

Which of these is most important for an enzyme to be able to perform its function?

The overall shape of the enzyme is important, but actually it is the structure of one particular part, called the active site, that is most significant. This is where all the reactions take place, so if that part is the wrong shape, the enzyme won't function.