Without enzymes, we would never function!
Every chemical reaction our bodies need to survive- respiration, digestion, even thinking- all depend on fast reactions maintained by enzymes.
Both chemistry and biology are mad about enzymes, so let’s get going!
1. Question: Who are they?
Answer: Well, enzymes are a type of protein made by cells.
Reminder: A protein (or polypeptide) is a polymer of a chain of specifically ordered amino acids which is then folded.
The amino acid chain is folded and held in place by chemical bonds, giving a unique 3D shape.
For enzymes, the final structure always includes an area called an active site, and the shape always only matches one molecule!
So NO FIT = NO REACTION!
2. Question: What do they do?
Answer: They are biological catalysts!
A catalyst speeds up reactions WITHOUT BEING USED UP
3. Question: How do they work?
Answer: THE LOCK AND KEY HYPOTHESIS:
a. The right specific enzyme is present, with its active site being the right fit for the starting ingredient or substrate.
b. The substrate attaches to the active site, and this match is described as the enzyme-substrate complex
c. The speed of the reaction increases, a product is made and the enzyme is reused
Factors of Reaction
Every enzyme has its own ideal temperature and pH!
Let's start with TEMPERATURE:
There are 3 key points:
- Every enzyme has its favourite temperature
-Changing the temperature will change the number of successful collisions
-Too much heat can denature the active site
So let's break it down:
The chemical bonds holding the amino acids in their 3D shape are sensitive to levels outside the enzyme’s ideal range, and most boiling temperatures damage an active site beyond repair.
So this is where we discuss denaturation!
Being denatured means the active site starts to breakdown because too high a temperature is breaking the chemical bonds.
Denaturation can lead to the whole reaction slowing down and no product being made.
Also, enzyme-substrate complexes are dependent on collisions between the enzyme and the substrate.
The enzyme and the substrate need energy to move around so they have a better chance of hitting each other and reacting.
But if the temperature dips too low, there is less movement and so less chance of successful collisions being made, slowing down the reaction.
And let's not forget pH!
This can also have a big impact on the active site shape, again because of the sensitivity of the chemical bonds between the amino acids in the folded 3D structure.
If the pH makes a huge change outside the enzyme’s comfort zone, the active site will be denatured, the substrate won’t be able to fit, which, you guessed it, slows the reaction right down!