Proteins have so many roles in living things – from enzymes which do chemical reactions, to ‘cell messengers’ that cells use to communicate with each other, to structural elements that make up the ‘skeleton’ of cells. Collagen is a protein that along with calcium phosphate is what your bones are made of. Your hair and nails are made of a protein called keratin. Antibodies are proteins which recognize foreign invaders such as bacteria and viruses when you get an infection. Proteins can be so different in function – from the transparent lens of your eye, to the fibres in your muscle tissue.
Obviously with all these proteins flying around, proteins themselves can be used to effect the workings of the human body. People with diabetes can take insulin, for example, which is a protein messenger that regulates how the body uses sugar. Alzheimer’s disease is thought to potentially be due the presence of ‘misfolded’ proteins in the brain. There are toxic proteins, such as botulinum toxic (from the bacterium Clostridium botulinum) and ricin (from the castor oil plant) of which a minuscule amount will certainly kill you.
It’s amazing to think that all this variety comes from chains made from only 20 types of amino acids linked together in different combinations. This is why I think proteins are so interesting, and making them is so fun!