The Biology Guide: Enzymes
- symthasreeskoganti
- 1 day ago
- 4 min read
Fairfax, VA
Introduction
For students interested in studying living organisms, the AP Biology course or biology courses in general can be useful to sign up for. The content of these courses often presents students with basic scientific skills and a wide range of information, from ecosystems to the principles of life to genetics. One of the most important topics within biology is enzymes, which refers to a specific subset of proteins important for biological reactions across organisms. Every day, thousands of chemical reactions take place inside of you and are sped up by enzymes. These proteins are vital for daily function and therefore are a key foundational concept of biology.
Structure = Function
The mantra of enzymes is that structure equates function. As enzymes are proteins, they are composed of amino acids that determine their primary structure. This chain of amino acids held together by peptide bonds can fold in certain areas into shapes of alpha helices and beta pleats, secured by weak hydrogen bonds. Even this overall structure can be folded further, resulting in the final 3D shape with a unique structure and active site. This site is important as it is critical to the function of an enzyme. It acts as a region for the substrate to bind to, triggering temporary change in the enzyme structure and catalyzation of the reaction. The active site must be complementary to the substrate’s shape, which is why structure is so crucial to an enzyme’s function. Think of a key being inserted into a lock; the type of fit seen in this example is akin to that of a substrate and enzyme. Allosteric sites, different from active sites, are also present on enzymes, and are where certain regulatory molecules can bind to activate or inhibit enzyme function through changing the shape of the enzyme’s active site.
How It Works
An enzyme’s purpose is to speed up a reaction, making it more efficient and allowing for more of a reaction to take place in a given span of time. The main concern of a reaction is something called activation energy, which is essentially the amount of energy needed to be input for the reaction to be carried out. The activation energy is needed to have the substrate, a reactant molecule, reach a state of higher energy (i.e. a transition state). When enzymes bind to the substrate at their active sites, the enzymes work to reduce the needed activation energy, allowing the energy threshold to be overcome faster and the reaction to be carried out more quickly.
There are a few main ways in which this acceleration can happen. Two or more substrates could be bound to an enzyme’s active site, wherein the substrates being in the proper orientation and proximity to react lets them reach that transition state much quicker. In another case, when the substrate binds to the enzyme, the substrate and enzyme can be triggered to have changes in shape. The changes in shape to the substrate through weakening of its bonds allow for it to reach a transition state faster.
A Couple of Barriers
Just like an employee, enzymes can have optimal conditions to be able to function. If an employee is going through lots of stress, they may not be able to work to their fullest capacity. In the same way, changes outside of the optimal pH and temperature range can denature the enzyme, or alter the bonds forming the enzyme’s structure, making it unable to bind to substrates as effectively and carry out its job. Substrate concentration can also affect the rate at which enzymes function; with a decreased amount of materials, a decreased amount of reactions will be carried out. At very high substrate concentrations, the rate of reaction for the enzyme will plateau because the enzymes are already working to their fullest capacity.
You now know how enzymes work!
Take some time to do some active learning to test your understanding:
What is an enzyme? What is it made of and what job does it carry out?
Can you explain why structure is so important for an enzyme?
Enzymes are crucial to our body’s functions. Explain how having a very high fever (ex: 104 C) could affect enzyme activity and contribute to the feeling of being sick.
Do some research! Find one example of an enzyme and understand which method it uses to help the substrate reach the transition state faster.
Key Vocab:
Activation energy -- the minimum amount of energy required to start a chemical reaction
Active site -- region of an enzyme where substrate molecules bind and undergo a chemical reaction
Allosteric site -- regulatory binding location on a protein, distinct from the active site, where molecules can bind to increase or decrease enzyme function
Substrate -- the specific molecule that an enzyme acts upon to catalyze a chemical reaction
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