ELI5: Explain Like I'm 5

Enzyme Commission number

Have you ever helped your mom bake a cake? Do you remember adding some ingredients like sugar, flour, and eggs, and mixing them together? Think of the cake recipe as a set of instructions to make the cake. Similarly, the cells in our body also have sets of instructions called enzymes that help them do their job.

But, what happens when the cells need to do something complicated, like breaking down a big molecule into smaller pieces so they can use it for energy? That's where Enzyme Commission Numbers (EC numbers) come in handy.

EC numbers are like a set of instructions for enzymes. They are used to describe what type of chemical reaction an enzyme can do. An EC number has four parts, like this - 1.2.1.4.

The first number (1) tells us what type of reaction the enzyme does. For example, all enzymes that start with 1 are oxidoreductases which means that they can add or remove electrons from a molecule.

The second number (2) gives more details about the type of molecule the enzyme works on. For example, if the second number is 3, it means that the enzyme works on carbohydrates.

The third number (1) tells us even more about the specific type of reaction. For example, if the third number is 2, it means that the enzyme is involved in transferring a molecule from one place to another.

Finally, the fourth number (4) specifies which molecule is being acted on. For example, if the fourth number is 6, it means that the enzyme works on alcohols.

Putting all of these numbers together gives us a unique code that tells us exactly what chemical reaction the enzyme can do.

So, just like a recipe helps us make a cake, EC numbers help cells know what enzyme to use for different reactions. And just like how we need to follow the recipe to get a tasty cake, cells need to use the right enzyme with the correct EC number to keep their body working properly.