In this video, we're going to begin our lesson on enzyme binding factors by introducing the enzyme substrate complex. And so when an enzyme interacts with its substrate, the substrate is going to bind to the enzyme specifically at a region called the active site. And so when the substrate binds to the enzyme at the active site, this ends up forming the enzyme substrate complex. And the enzyme substrate complex is commonly abbreviated as just ES. So I'll put ES here. And so the active site, once again, is defined as a very specific region of an enzyme that binds the substrates. So let's take a look at our image down below to look at how substrate binding forms the enzyme substrate complex. And so notice over here on the far left, we're showing the enzyme over here in red, and the enzyme is commonly abbreviated with just an 'e'. And then notice that in black right here, we're showing you the substrate which is really acting as the reactant for this enzyme catalyzed reaction, And substrates are commonly abbreviated with just the letter 's'. And so notice that when the substrate active site. And the active site is just the specific region of the enzyme that binds the substrate. And so the substrate here is going to bind to the active site of the enzyme, which the active site of the enzyme is just this region that we see right here. And so, this other region over here is not going to be the active site. The active site is this region right here. So the active site is just a specific region on the enzyme that binds the substrate. And so once the enzyme is bound to the substrate, it ends up forming the enzyme substrate complex. And so here in the middle, we can see the substrate is bound to the enzyme, and they are making this fit together. And so, the enzyme substrate complex is commonly abbreviated as just ES complex. Now after enzyme catalysis, it's the products that are going to be released from the active site, and the enzyme is going to remain unchanged in the reaction. And so notice that after enzyme catalysis, which would be represented by this arrow right here, the substrate in black is being converted into the product over here, which is in green, and the products are commonly abbreviated with just a 'p'. But notice that the enzyme is actually unaltered, it is unchanged by the end of the reaction. And so the enzyme still takes on the original form that it had before the reaction even took place. And so this is what we mean by the enzyme being unchanged. And because the enzyme is unchanged, it means that it can continuously catalyze this reaction over and over and over again to continuously make more and more product over time. And so this here concludes our introduction to the enzyme substrate complex. And as we move forward, we'll be able to talk about some more enzyme binding factors. So I'll see you all in our next video.
Enzyme Binding Factors - Online Tutor, Practice Problems & Exam Prep
Enzymes catalyze reactions by forming an enzyme-substrate complex (ES) at the active site, where the substrate binds specifically. Some enzymes require cofactors, non-protein substances that assist in catalysis, such as metal ions. Coenzymes, a type of cofactor, are organic molecules derived from vitamins. Cofactors enhance substrate binding, enabling the enzyme to convert substrates into products while remaining unchanged, allowing for repeated catalysis. Understanding these interactions is crucial for grasping enzyme functionality and metabolic processes.
Enzyme-Substrate Complex
Video transcript
Cofactors
Video transcript
In this video, we're going to introduce cofactors. Some enzymes require what are known as cofactors. Cofactors are defined as non-protein substances that are required by an enzyme for catalysis to occur. If there is no cofactor, in some substances, no enzyme catalysis can take place. You can think of cofactors as basically little enzyme helpers. They help the enzyme perform enzyme catalysis. Not all enzymes have cofactors, but some enzymes do. An example of cofactors includes metal ions. Some enzymes will not be able to perform catalysis without metal ions. Metal ions are non-protein because they're not made up of amino acids like proteins are. Instead, they're just metal ions. Cofactors are not consumed in the reaction, which means that at the beginning of the reaction and by the end of the reaction, the cofactor remains the same. Cofactors can actually assist with enzyme catalysis in many different ways, and we'll be able to see an example of how they can assist down below in our image.
A coenzyme sounds a lot like a cofactor and that's because it is a cofactor. A coenzyme is a very specific type of cofactor. A coenzyme is defined as an organic molecule cofactor. If the cofactor is an organic molecule, meaning that it's containing carbon and hydrogen atoms, then we refer to it as a coenzyme. Not all cofactors are coenzymes because not all cofactors are organic molecules. For example, metal ions are just made up of metal atoms. They're not containing carbon and hydrogen atoms. Thus, it's only the cofactors that are organic molecules that we call coenzymes. Coenzymes tend to be derived from vitamins.
Let's take a look at our example down below to get a better understanding of how cofactors can assist enzymes with catalysis. Some cofactors can assist in substrate binding. When we look at our image down below on the left-hand side, notice that the enzyme is shown here in red and the substrate is shown here in black. But notice that the enzyme's active site here is not really tailored for this substrate. Perhaps, in some scenarios, the substrate could not bind to the active site because the active site is not perfectly tailored for the substrate. If that happens, then the enzyme will not be able to perform catalysis. However, if a cofactor is present, such as this orange structure right here representing the cofactor, then the cofactor can come and bind into the active site. Notice here, the cofactor is bound to the active site, which could make the active site better suited and better tailored for the substrate. Only in the presence of the cofactor will the substrate actually be able to bind into the active site. Once the substrate has bound into the active site, as we have over here on the far right, then enzyme catalysis can proceed, and the enzyme can convert the substrate into the product, which is not being shown here, but you can imagine the reaction continuing here as normal.
This concludes our introduction to cofactors and how they are non-protein substances that are required to help enzymes perform catalysis. We'll be able to get some practice applying these concepts as we move forward in our course, so I'll see you all in our next video.
The organic non-protein components that aid in enzyme catalysis are called:
Reactants.
Cofactors.
Coenzymes.
Substrates.
Products.
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