Lock and Key Hypothesis: Understanding Enzymes

Enzyme Catalase, A Very Important Antioxidant In OrganismThe enzymes in living organisms are very large molecules that are essentially responsible for sustaining human life. Enzymes perform thousands of metabolic processes that keep a living organism alive, but there is no guaranteed explanation for how it works. What makes enzymes even more interesting is the fact that they are highly selective. An enzyme isn’t activated by just any substrate. In fact, enzymes only catalyze certain reactions and it chooses specific substrates involved in the reactions.

Enzymes are complicated molecules, but they only make up one component of the various things that go on in living organisms on a molecular level. If you’re interested in learning more about molecular organisms and how they help sustain life, then you should check out the Udemy course, An Introduction to Basic Biology. 

Characteristics of Enzymes 

Enzymes work in a very unique manner. The way that an enzyme catalyzes a chemical reaction is to start by building a substrate or several substrates to an active site on the enzyme. This active site is the region on an enzyme that combines with the substrate. When a substrate and an enzyme bind, the actions cause the distribution of electrons in chemical bonds of the substrate to change. This eventually leads to a chemical reaction, which leads to the product.

When the product is made, the enzyme releases it and it begins to regenerate for another cycle of chemical reactions.

The lock and key hypothesis is focused on the active site. The active site of an enzyme has a very unique geometric shape and it is only complementary to a specific substrate molecule. Imagine a puzzle piece. There are only a few pieces that fit with that one piece. Because the active sites are so geometrically unique, an enzyme can only work with a few or just one substrate.

The study of enzymes is very detailed, and there are several aspects to it. For a research in biology, enzymes are always a good topic to use. If you’re writing for a biology class, and you want to create a great paper about enzymes, then you should check out the Udemy course A+ Research Paper in Biology.  

Lock and Key Hypothesis

In order to explain why enzymes have such a high level of specificity, Emil Fischer in 1894 suggested that both a substrate and an enzyme have specific geometric shapes that fit exactly into each other. This idea of both substrates and enzymes having a natural geometric fit has been called the lock and key hypothesis.

The problem with this hypothesis is that it doesn’t explain the stabilization of the enzyme. When an enzyme has a substrate enter into its active site, the enzyme will change its shape slightly to match the substrate. If the enzymes were to be specifically designed to fit a substrate, then there would be no need for it to have to adjust its shape.

In 1958, another scientist named Daniel Koshland suggested a slight modification to the lock and key hypothesis. Koshland’s suggestion was that since enzymes were so flexible, the active site is constantly being reshaped by its interaction with the substrate.

Koshland suggested that substrate doesn’t bind to an active site as if it were specifically the right shape, but that the amino acid side-chains that are a part of the active site are molded into a specific position. This position allows the enzyme to start the catalyzing process. Koshland’s modified suggestion has been called the induced fit theory. 

The Way Enzymes and Substrates Interact 

Since these processes occur on a molecular level, it can be difficult to determine how things work. Enzymes vary in their specificity. While there are some enzymes that are only compatible with a single substrate, there are other enzymes that are compatible with several substrates, such as those with similar side chains, positions on a chain, or functional groups.

The enzymes that are least specific will catalyze a reaction no matter what the structural feature maybe as long as it matches a specific chemical bond.

There’s quite a bit of experimentation that goes into understanding how enzymes and substrates interact with each other and what makes them function in such a unique way.

Even more surprising is that outside of the lock and key hypothesis or the induced fit theory, there are various factors that have an impact on enzyme activity. For example, the temperature at which enzymes work is anywhere between 0 to 60 degrees Celsius with the optimum temperature being approximately the body temperature.

In the case of the temperature being too high, the shape of the active site on an enzyme gets altered, which makes it impossible for the substrate to fit. If the temperature is too low, the substrate just doesn’t have enough energy to move into the active site.

Not only that, but there are six types of enzymes that all have different characteristics and functions. With all of these different factors, and the fact that enzymes do thousands of processes a day, it can be hard to definitively determine what makes enzymes so specific to substrates. Until then the best conclusion that has been made is the lock and key theory.

Learning More about Biology 

Enzymes are vital to not just your life, but the lives of every living organism in the world. Without the actions of enzymes, it would be impossible to do anything. Understanding how they work is one of the most difficult things to do in biology. It can be hard to just learn the basics about these molecules. If you’re interested in learning more about enzymes and the way they work as well as other subjects in biology, then you should check out the Udemy course on GCSE Biology.

Unfortunately though, the information can get complicated from time to time, and retaining all the information may become a hassle. If you’re having trouble learning complicated topics in biology and other courses, then check out the Study Tips course that Udemy offers for students, or any other individual that wants to boost their learning skills.