Biology basics: Proteins

Proteins are present in biology everywhere. Without we wouldn't exist. Nor would bacteria, fungi, viruses, pet dogs and our gold fishes..... Proteins are essential to all forms of life and this is why it is important to understand them.

What is a protein?

Proteins are long molecules that consist of reoccurring subunits called amino acids. Proteins are needed for our bodies and the cells in our bodies to function properly. Our body structures: cells, tissues and organs cannot exist without proteins.

Enzymes, many hormones and antibodies that we hear about are proteins. Hemoglobin which carries oxygen in the blood are also proteins. Many neurotrasmitters, involved in the transmission of messages between nerve cells, are also proteins.

Almost every biological process involves, in one way or another, proteins. Examples of the functions of proteins in the human body are:

• Enzymes which makes biochemical reactions occur faster
• As antibodies for our immune system
• As hormones, which help cells signal between each other and coordinate events in the body (such as menstruation in females.
• The hemoglobin protein transports oxygen through the blood.
• The rhodopsin is a protein in the eye is vital for vision
• Muscle contractions involves two types of proteins (actin and myosin) are involved in muscle contraction and movement.

What are amino acids?

These 20 amino acids are make up proteins can be arranged in many different ways to create millions of different proteins, each one with a specific shape and specialised function in the body. Anfinsen showed that the sequence of amino acids (primary structure) was what determined the final shape of the protein. The twenty amino acids are:

• Alanine
• Arginine
• Asparagine
• Aspartate
• Cysteine
• Glutamate
• Glutamine
• Glycine
• Histidine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Proline
• Serine
• Threonine
• Tryptophan
• Tyrosine
• Valine

How proteins fold?

Proteins need to fold into specific three-dimensional shapes to work properly. Anfinsen's experiment showed that many proteins can fold without help. Some proteins can still need a bit of help from special proteins called chaperones. These protein separate the folding protein from other cellular components so the protein can fold in peace, without being disrupted by multitude of other things present in the cell. To get a feel of how proteins fold, have a look at the video below that shows a protein folding.

This simulation requires lots and lots of computational power. The simulation was made possible with folding@home, where more than 280,000 people all around the world donated unused computer power (when their computer was idling). Protein folding is very sophisticated and often does require the combined power of 280,000 to model.

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From their website:

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Get support, join a team, and learn how your computer and (as of today) 281,427 others contribute to finding cures for some of life’s most threatening illnesses.

Visit their site at http://folding.stanford.edu/. I think it's a lovely movement. Hundreds of thousands of people uniting to fight disease. Sounds incredible, doesn't it?