Intro to Coenzymes: Study with Video Lessons, Practice Problems & Examples

Coenzymes play a crucial role in enzymatic reactions, particularly in redox reactions catalyzed by dehydrogenases. Key coenzymes include ATP (adenosine triphosphate), which stores energy in its phosphate bonds; NAD⁺ (nicotinamide adenine dinucleotide), involved in oxidation-reduction reactions; FAD (flavin adenine dinucleotide), which participates in various metabolic processes; and coenzyme A, essential for acyl transfer reactions. Understanding these coenzymes is vital for grasping metabolic pathways and energy transfer in biological systems.

Intro to Coenzymes Concept 1

Hey everyone. In this video, let's take a tour of some common types of coenzymes. Now here we're going to say that many reactions we see will involve redox reactions catalyzed by dehydrogenases. These are our redox enzymes and they require these enzymes to become active. Now the types of coenzymes we're going to discuss here, the most common ones we all need to know are the following.

So here we have the coenzyme and then we have its structure. ATP, which we know is adenosine triphosphate. So we have our adenosine portion, which is our ribose sugar, connected to this nitrogenous base adenine. On carbon number 6 of the ribose sugar, we have these 3 phosphates connected to them. The energy of ATP is stored within these phosphorus-oxygen bonds.

Another type of coenzyme is NAD⁺. Here we have Nicotinamide Adenine Dinucleotide. So we still have our ribose sugar. We have ADP now instead of ATP. And then we have our Nicotinamide right here. Here we have basically a nitrogen group here.

It is protonated on this nitrogen, and here we have an amide group. FAD, flavin adenine dinucleotide. So we have our flavin here which is connected to ribitol and then again ADP. And then finally, coenzyme A, its name is there, coenzyme A. We have our Aminoethane Thiol.

We have our Pantothenic acid, and then again ADP. Notice that ADP is a recurring portion of many of these coenzymes. And when it comes to the coenzymes, these are the ones that you should remember. There's more than these, but these are the ones that are of importance within this course.

Intro to Coenzymes Example 1

In this example, we have to identify the substrate, coenzyme, and product for the following reaction which involves the enzyme Succinate dehydrogenase. Alright. So, we're going to say here, Succinate would have to be our substrate because we said earlier that one of our common coenzymes is FAD. The question doesn't ask this, but we know that this ends with ACE, so this would represent our enzyme. The enzyme and this coenzyme put together make it active in order to change our substrate, succinate, into fumarate.

Fumarate here would have to be our product. In this process, we've created FADH₂. So FAD has been transformed into FADH₂. Here, this is just another product but not the main product that we're concerned with. So, here again, Succinate will be our substrate.

FAD is one of our common coenzymes. We have our enzyme that works in conjunction with it to create fumarate which is our product.