Introduction

Why does protein structure matter? Proteins are the ‘working’ molecules of life. Almost everything that a cell does is carried out or controlled by proteins. It is helpful to think of them as molecular machines, not simply as nutrients. 

Protein structures matter because what a protein does is intrinsically linked to the shape of the protein, and how the protein arranges chemical groups in three dimensional space. If you change the shape of the protein, you often change or even inhibit its function.

For example:

• Structural proteins such as actin and tubulin assemble into long filaments. These filaments give cells their shape and help them move.
• Enzymes are proteins that speed up  chemical reactions. Their structure positions specific chemical groups in three-dimensional-space to facilitate a chemical reaction. Digestive enzymes such as trypsin, pepsin and amylase break food into small usable molecules.
• Many hormones are proteins. Their three-dimensional shape allows them to bind precisely to receptor (also proteins) triggering signals that control communication between cells
• Transport proteins carry important molecules needed for life. Haemoglobin, for example, has pockets perfectly shaped to bind oxygen in the lungs and release it in tissues where oxygen is needed.
• Antibodies are proteins that recognise foreign molecules. Their specific shapes allow them to bind tightly to invaders, helping the immune system detect infection.