Protein: What is it?

Protein: What is it?

In previous articles I talked about some of the structural and functional roles that proteins have in the body – there are many many more – later articles will explore some of the other roles that proteins have in our bodies. But for now let’s step back to the definition of protein in the Merriam-Webster dictionary: “any of various naturally occurring extremely complex substances that consist of amino-acid residues joined by peptide bonds, contain the elements carbon, hydrogen, nitrogen, oxygen, usually sulfur, and occasionally other elements (such as phosphorus or iron), and include many essential biological compounds (such as enzymes, hormones, or antibodies)”.

Lots to unpack from that definition.

The dictionary says that proteins are “naturally occurring”.  Proteins can be synthesized in a lab – I will discuss this topic in a later article – but for the most part all of the protein we eat was made by another animal, a plant or microorganism. All living organisms make protein. A “sort of exception” to this would be viruses. Viruses use the protein making factories of a living cell to make their proteins and replicate. Many biologists don’t consider viruses “living organisms” in part because of this fact.

Next let’s pull out the phrase “amino-acid residues joined by peptide bonds”. So what are “amino-acid residues”? A residue of anything is what is leftover after something is removed.

When proteins are being assembled by an organism the process involves removing a portion of the amino acid structure before what is leftover is connected to another amino acid residue by a new chemical bond.

Amino acids are, by name: “acids”.  When many people hear the word acid they think of danger; like what is implied in the standard warning symbol below you have seen on labels of chemicals.

It might seem odd to you that we would want to be eating acid containing foods and some might wonder if eating too much protein would make you too acidic (more on that later). Why amino acids or any other substance are called acids is beyond our discussion today. If you are really interested in why something is called an acid check out my page on biochemistry.

Our protein making machinery takes amino acids and joins them together with a new bond called a “peptide bond”. 

This bond is formed by removing an oxygen and hydrogen from one amino acid and a hydrogen from another amino acid and then bonding a carbon from one amino acid to the nitrogen of another amino acid. The “waste product” of this process is H2O.

Kind of cool to think we make water as a byproduct of making proteins.

The way our cells make proteins is very much the same way that a plant makes proteins or even the simplest one cell organism such as  bacteria makes proteins. That is not to say that making proteins is a simple process. Proteins; as the definition states, are “extremely complex substances” – the process, while very similar in all creatures living today – is not simple. How every single living organism makes proteins is mind bogglingly complex and absolutely amazing. We can explore this fascinating process in a later article.

Proteins are made up of many different elements, however the star player is nitrogen. As many in the agricultural business know nitrogen is essential for growth. The “Nitrogen Cycle” is one of the most important concepts taught in biology. The nitrogen cycle is key to our existence – for more information check out my page on biochemistry.

The next article in this series will continue with more discussion about the different amino acids we need to make proteins. If you are ready to read that article now click here. Otherwise I will send it out to my subscribers and post it to Facebook in a week or so.

Russ