Difference Between NAD and FAD

Difference Between NAD and FAD

Coenzymes are essential for the proper functioning of the many processes that take place in our bodies. Coenzymes are molecules that function as catalysts in chemical processes and aid in the production of energy. It serves as a catalyst, accelerating the rate of the reaction. Coenzymes are chemical substances that are complex in nature and are formed from vitamins and other critical elements that our bodies need in little quantities. NAD and FAD, two coenzymes that are essential for a variety of processes, are required.


It is important to note that the primary difference between NAD and FAD is that NAD can only receive one hydrogen atom, while FAD can accept two hydrogen atoms. NAD is an abbreviation for Nicotinamide Adenine Dinucleotide, whereas FAD is an abbreviation for Flavin Adenine Dinucleotide. The activities of the two coenzymes are distinct; for example, NAD is a coenzyme that is present in all living organisms, whereas FAD is a cofactor that is involved in a variety of metabolic and complicated processes.

NAD (nicotinamide adenine dinucleotide) is a coenzyme that is very important for our metabolic process. It may be present in all of the cells in the body that are still alive. In accordance with its name, a dinucleotide is composed of two nucleotides that are linked together by phosphate groups. NAD may be found in two different states or forms, namely, the oxidized form and the reduced form or state. It is also engaged in other activities, including redox reactions, which transport electrons from one end of the cell to the other end of the cell.

FAD is an abbreviation for When it comes to metabolism, the flavin adenine dinucleotide cofactor, which is also known as a coenzyme, plays a role in a variety of enzymatic processes that are required for the process. There are many members of the Flavin group. If a protein component is present, the group becomes known as flavoprotein. If flavin occurs in another form, then the group is referred to as flavin mononucleotide. It exists in four different redox states. It may become stable by accepting or donating one electron, depending on the situation.

What is NAD?

Nicotinamide The adenine dinucleotide, often known as NAD, is made up of two nucleotides that are bonded together by a phosphate group. It is used in DNA replication. Depending on its condition, it may exist in either an oxidized or a reduced form (NADH or NAD+), depending on its function. Because its cofactor may be present in both oxidizing and reducing cells, it can function as both oxidizing and reducing agents. Essentially, NAD’s primary job is the transport of electrons from one location to another.

The nucleotides adenine nucleobase and nicotinamide are the two types of nucleotides. Besides assisting in electron transmission, it also contributes to the cellular process by serving as a catalyst or reagent for enzymes, and it may also add and delete chemical groups from the protein itself. NAD and its enzymes are so critical in the body that they are becoming more significant in drug development. The molecular formula for this substance is C21H27N7O14P2.

It has a molar mass of 663.43g/molecule and is a cationic compound. Its melting point is 60 degrees Celsius (320 degrees Fahrenheit; 433 degrees Kelvin). Regardless of its condition, it has the appearance of a white powder and is both hygroscopic and extremely water-soluble(highly) in nature. Because of the presence of adenine in it, it has the ability to absorb UV light. It does not pose a threat. It functions as a donor molecule and messenger molecule for ADP ribose in the body. It also serves as a substrate for the replication of DNA and other extracellular processes.

What is FAD?

Flavin adenine dinucleotide (commonly known as FAD) is a nucleotide that is very important in the area of biochemistry. It is a redox-active coenzyme that has been shown to be related to a variety of different protein types. It may occur in four different states: quinone, semiquinone, flavin-N(5)-oxide, and hydroquinone, to name a few examples. In its oxidation state, FAD takes two protons and two electrons to form FADH2, which is the product of the reaction.

Similar to NAD, FAD is made up of two components: the adenine nucleotide and the flavin mononucleotide (FMN), which are linked together by phosphate groups. When two hydrogen atoms and two electrons are accepted by FAD, it may be reduced to generate FADH2. Afterward, FADH2 may be oxidized to generate a more stable form of FADH by giving one hydrogen and one electron atom each. The formation of FAD may be accomplished by a variety of methods, including reduction, oxidation, and dehydration.

FAD appears in a variety of hues depending on its status. It becomes yellow-orange, just as it would if it were in a severely oxidized condition. When completely oxidized, it takes on a yellow appearance. In its half-reduced state, it has a pH that is either red or blue in hue, and when entirely reduced, it becomes colorless. It is represented by the chemical formula C27H33N9O15P2. 785.557 grams per mole (molecular mass) is the molar mass of this compound.

Difference between NAD and FAD

  • One kind of NAD is a Nicotinamide Adenine Dinucleotide, which is composed of adenine nucleobase and nicotinamide that are linked together by phosphate groups. Flavin adenine dinucleotide (FAD) is a nucleotide composed of a flavin group or a flavin mononucleotide that is linked together by phosphate groups.
  • NAD is a coenzyme that is present in the mitochondria of living cells. In addition to being a redox cofactor, FAD is engaged in a variety of metabolic and complicated processes.
  • When NAD is created during the glycolysis and Krebs cycles, it is reduced to NADH, which is then recycled.
  • When FAD is created exclusively during the Krebs cycle, it is reduced to FADH2.
  • NAD can only take one hydrogen atom at a time. FAD has the ability to receive two hydrogen atoms.
  • NAD donates an electron to Cytochrome Complex 1, resulting in the production of three ATP for every NADH generated. FAD donates an electron to Cytochrome Complex 2 and generates two ATP for every molecule of FDH2 generated.


Both NAD and FAD are involved in the process of cellular respiration in a significant way. Both are produced from proteins and are capable of accepting and transporting high-energy electrons to the electron transport chain. The enzymes NAD and FAD are both involved in the synthesis of ATP molecules. NAD is generated from a molecule known as Niacin, which is sometimes referred to as Vitamin B3. FAD is generated from a chemical substance known as riboflavin, which is also known as Vitamin B2 in certain circles.

Both are coenzymes, which means they work together. NAD is critical for the transport and delivery of hydrogen and electrons during the metabolic reaction, while FAD is responsible for the production of ATP via the usage of electrons and hydrogen. Through the processes of oxidation and reduction, both are engaged in the catabolic and anabolic processes.

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