What exactly are proteins, and how do they work?
Biology has perfected life for billions of years, but this would not have been possible without the appearance of proteins
You are probably familiar with the fact that we are all made of cells, and that the same applies to all living things on earth. Those cells are tiny capsules that separate life from the dead universe. Have you ever wonder what exactly is happening inside the cells? Or how can those cells combine and build amazing things like human beings, trees, or even cats?
Biology has perfected life for billions of years, but this would not have been possible without the appearance of proteins. Think of proteins as autonomous nano-scale machines that provide cells with energy, workforce, weaponry, and construction material.
Proteins are molecules made up of chains of amino acids, smaller subunits that combine and generate 3D structures. Imagine building lego machines from an unlimited source of 20 different pieces. For a small protein comprising 100 legos (amino acids), you can make 20¹⁰⁰ different machines.
The flexibility of proteins provides biology with a myriad of different functions. In the human body, there are more than 100,000 proteins at work, all serving critical functions. Keratin and collagen are essential components of your body, forming hair, teeth, and connective tissue for bones and muscles. Hemoglobins are vital proteins that store oxygen in your red blood cells.
Enzymes, the most advanced machines in the world
Among the various types of proteins are a class called enzymes. They serve as biological catalysts, meaning that they are the chemical-reaction machines that build molecules or break them down as needed, transforming our world with atomic precision. Thanks to these reactions cells grow, reproduce, and sustain themselves.
Enzyme and protein functions are closely related to their 3D structure. While they float around in the aqueous environment inside the cell, proteins cluster together to form complicated shapes that fit specific molecules or other proteins, creating new complexes or generating distinct chemical reactions.
Evolution did its thing…
Over the years proteins evolved driven by environmental pressure, changing their amino acid sequence and altering their shape.
At some point, billions of years ago, ancient cells needed to move around to search for food or escape from other predatory ones. They developed specific proteins to build long rotatory tails propelled by intricate molecular engines. Eventually, those cells needed fuel to keep up movement, so proteins constructed fuel generating motors like the ATP synthetase.
This evolutionary process went on and on and resulted in the diverse biology we see today. From viruses to elephants, we can even find proteins in our food and medicines.
Proteins & humankind
It was not late in human history that we started to take advantage of proteins. Our forebears produced cheese from milk more than 7,500 years ago, without knowing that they were using enzymes to cut and restructure caseins, another protein in milk.
Beer and winemaking require yeast to transform sugars into alcohol. But if we look carefully at what is happening inside the yeast cell, we’ll notice that sugars are split, processed, and digested by multiple proteins to release flavors and alcohol.
The gelatin in your jello shots and gummy bears is protein — fragments of collagen. Collagen originally evolved to produce structure, organize cells, and provide physical barriers (and now, coincidentally, often finds itself drowning in vodka!). Collagen is in our skin and is the most abundant protein in mammals. This protein can form dense networks, and depending on the number of collagen units and the web’s complexity, it can result in strong and rigid, or soft and melty materials.
And what about medicines? Insulin — you guessed it! — is an essential protein used worldwide to help people with diabetes.
We discover new and exciting proteins every day. Some of them can digest plastics and could help us fight pollution. Others are efficient defense systems that protect our bodies from pathogens.
Proteins already play an essential role in our daily life. But as we face some of the world’s biggest challenges in future, proteins are also one of our best chances to use nature’s own ingenuity (with a bit of help from our protein engineers) to develop sustainable solutions for those problems.
For more interesting proteins check Protein Data Bank molecule of the month.
Leonardo Alvarez | CEO & Co-founder at Protera | Computational Biology | Deep Learning & Proteins.