Biochemistry: Enzymes

It's a day like any other, and in Stomach and Duodenum, the citizens are having a great time. But what is this? Things start falling from above. Everyone needs to act fast! Only superheroes can handle this!

It’s time to call the Enzyme Squad! This is not an action movie; this actually happens in your body, all the time! Enzymes are proteins that regulate many of the processes going on in your body. With their superpowers they are able to speed up different chemical reactions that would normally happen at a very slow pace. They are catalysts.

Each enzyme is specialized for a specific reaction, and can handle only this. For example amylase is really good at splitting up starch molecules into sugars. But it can’t handle any other opponents, for example proteins. The enzyme that can deal with proteins is protease, which splits them into amino acids. Other enzymes are specialised for joining different molecules together to form longer chains and more complicated substances.

Often chemical reactions are more complex and occur in several steps, so some enzymes must work in teams to complete a mission. Glycogen synthase, for example, joins forces with other enzymes to turn glucose into glycogen. Just like all real superheroes, some enzymes also have their sidekicks, other non-enzyme molecules which activate the enzymes, and help them do their job - cofactors. But have you noticed something special about their names - amylase, protease, synthase...? They all end with “-ase”!

The first part of each enzyme's name tells us what process or what substance — substrate — it deals with. But the enzymes mentioned here are not the only ones. There are hundreds of different enzymes inside your body working all around the clock! Let’s look at one of them in action! This lactose molecule found in milk is too big to be absorbed in the small intestine.

If it’s not broken down, it will pass all the way to the colon. There, it will be fermented by bacteria, which can cause some very unpleasant symptoms such as bloating, stomach pain, gases, or even diarrhea. But here comes lactase from the Enzyme Squad! The enzyme lactase has a unique shape with a region called active site, into which lactose molecules fit perfectly. Lactose and lactase bind together to form an enzyme-substrate complex.

Lactase applies its superpower and accelerates the reaction that splits the lactose molecule into simple sugars - glucose and galactose. These simple molecules are the products of the reaction that just took place. When the reaction is completed, lactase releases the products, which can now be absorbed by the body. The enzyme remains unchanged, and can move onto other lactose molecules. Unfortunately, these superheroes have a weakness.

They are very sensitive, and can only do their job in very specific - or optimal conditions, such as the right temperature and right acidity. Outside these optimal conditions, their activity decreases significantly. If the temperature becomes too high, or the environment becomes extreme, an enzyme can change and become unable to perform its function anymore. It will become denatured. Most of the time, your body maintains a constant temperature, so that enzymes can thrive.

But enzymes exist outside the human body too. They are often used to catalyse chemical reactions, for example, in the food industry. The situation in Stomach and Duodenum has been contained for now. Thank you Enzyme Squad for a job well-done! What would the world do without superheroes like you?