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Difference Between NADH and NADPH

Main Difference

The main difference between NADH and NADPH is that NADH is used in cellular respiration while during the glycolysis and Krebs cycle to produce ATP via oxidative phosphorylation, whereas, NADPH is used in photosynthesis while during the Calvin cycle to assimilate Carbon dioxide.

NADH vs. NADPH

NADH is used in cellular respiration, while during the glycolysis and Krebs cycle and the reaction, they use an electron transport chain to produce ATP by oxidative phosphorylation, whereas NADPH is used in photosynthesis while during the Calvin cycle in the light reaction to assimilate carbon dioxide. NAD+, when they are subjected to reduction reactions, they form NADH, on the other hand, when NADP+ is reduced, they form NADPH. In the context of reduction reactions, it can be said that NADH is a reduced form of NAD+, whereas NADPH is a reduced form of NADP+.

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NADH also undergoes oxidization as it oxidizes to form NAD+ in the oxidation reaction; on the contrary, NADPH oxidizes to form NADP+ during their oxidation. NADH is involved in cellular respiration processes that can take place in the absence of light; however, NADPH is involved in photosynthesis that takes place in the presence of light. NADH is used in the electron transport chain to produce ATP by oxidative phosphorylation; however, NADPH is used in Calvin’s cycle to assimilate carbon dioxide.

NADH does not include a free group of phosphate; on the other hand, NADPH contains a free phosphate group attached to adenine moiety in 2’ position of ribose. NADH is involved mainly in catabolic reactions only, whereas NADPH is involved in reactions of anabolic. NAD+ is the most abundant form found compared to NADH; however, NADPH is the most abundant form which is found in the cells.

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Comparison Chart

NADHNADPH
NADH is used in cellular respiration while during glycolysis and Kreb’s cycle.NADPH is used in photosynthesis while during the Calvin cycle.
Reduction
NAD+ reduces to form NADH.NADP+ reduces to form NADPH.
Oxidized Form
It oxidizes to form NAD+.It oxidizes to form NADP+.
Involvement
It is involved in Cellular respiration.It is involved in photosynthesis.
Production
It is produced in glycolysis and Kerb’s cycle.It is produced in light reaction of photosynthesis.
Function
It is used in the Electron transport chain to produce ATP by oxidative phosphorylation.It is used in Calvin’s cycle to assimilate carbon dioxide.
Phosphate Group
It does not contain a free phosphate group.It contains a free phosphate group attached to adenine moiety in 2′ position of ribose.
Type of Reactions
These are involved in anabolic reactions.These are involved in catabolic reactions.
Abundance
NAD+ is the most abundant form found compared to NADH.NADPH is the most abundant form which is found in the cells.
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What is NADH?

NADH is referred mostly by its reduced form of NAD. It is one of the most abundant types of co-enzyme that is present inside the cells. These Co-enzymes are involved in carrying out the oxidation-reduction reactions during cellular aspiration. These are involved in carrying out cellular metabolism by serving donors for hydrogens and electrons.

NADH consists of two ribose molecules that are attached by phosphate groups. NADH is most intricate in catabolic processes only. It is produced while glycolysis and the Krebs cycle take place. Most of the dehydrogenase in cells use NAD+ as a co-enzyme in their catabolic reactions, as they donate hydrogen and electrons to form NADH. NADH also undergoes oxidization as it oxidizes to form NAD+ in the oxidation reaction.

In the context of reduction reactions taken the place of both of these co-enzymes, it can be said that NADH is a reduced form of NAD+. NADH is involved in Cellular respiration processes that can take place in the absence of light. NADH is used in the Electron carrying chain to form ATP by oxidative phosphorylation. NAD+ is the most abundant form found compared to NADH.

NADH is used in cellular respiration while during the glycolysis and Krebs cycle, and during the reaction, they use an electron transport chain to produce ATP by oxidative phosphorylation, NAD+ when they are subjected to reduction reactions they form NADH. In glycolysis, two NADH are produced, which can later be used in the conversion of ATPs; however, in the Krebs cycle, six NADH are produced. In addition to NADH produced in the Krebs cycle, two FADH2 are also produced, which serve as another co-enzyme as same as NADH. Both of these molecules can be used for the electron transport chain.

As NADH serves as an electron and hydrogen donor, by donating its electrons to protein membranes in the inner mitochondrial membrane, it serves its purpose. These electrons then later are used in the production of ATP by undergoing a process of Oxidative Phosphorylation.

NADH does not contain a free phosphate group. NADH contains two phosphate groups that are linked to an oxygen molecule; each phosphate group joins a five-carbon ribose sugar along with one of these phosphate group links to an adenine molecule while the other one links a nicotinamide molecule. NADH takes part in its reactions by accepting and donating electrons. NADH is involved mainly in catabolic reactions only.

What is NADPH?

NADPH is preferred mostly by its reduced form of NADP+. This NADP is the most abundant co-enzymes inside the cell. Like NADH and FADH2, it is also one of the most abundant types of co-enzyme that is present inside the cells. This NADPH is intricate in carrying out the oxidation-reduction reactions while the process of photosynthesis takes place.

NADPH is used in photosynthesis while during the Calvin cycle in the light reaction to assimilate carbon dioxide. These are involved in carrying out cellular metabolism by serving donors for hydrogens and electrons. They are mainly involved in carrying out anabolic reactions such as lipid synthesis or nucleic acid formation.

NADPH is the more frequent type of NADPH as compared to NADP. They are capable of donating hydrogens and electrons while in a chemical reaction. NADPH also referred to as the agent of reducing. When NADP+ is reduced, they form NADPH. Where in NADP+ contains two lesser electrons than its reduced form NADPH. This way, it acts as an electron transporting agent while also transporting hydrogen along with it.

Thus supplying electrons required necessarily for electron transport chain. In the context of reduction reactions taken the place of these co-enzymes, it can be said that NADPH is a reduced form of NADP+. NADPH is the most frequent type which is found in the cells. They consist of two ribose molecules which are attached by phosphate groups. NADPH also undergoes oxidization as it oxidizes to form NADP+ during their oxidation.

Each of these attached phosphate group ribose is connected from one side to the adenine group and another one with the nicotinamide group. However, it structurally differs from NADH with the presence of an additional free phosphate group in its structure. This phosphate group is attached to adenine moiety in 2’ position of ribose. NADPH is produced in the presence of light as the photosynthesis reaction takes place by the enzyme ferredoxin-NADP+ reductase.

During the Calvin cycle, the reduction power of NADPH is used to assimilate carbon dioxide. In animals, its function varies as it is used in the pentose phosphate pathway there. NADPH is intricate in anabolic processes. In plants, NADPH is involved in photosynthesis that takes place in the presence of light. NADPH is formed in light processes of plant photosynthesis.

Key Differences

  1. NADH is used in cellular respiration while during the glycolysis and Krebs cycle, whereas NADPH is used in photosynthesis while during the Calvin cycle.
  2. NAD+, when they are subjected to reduction reactions, form NADH; on the other hand, when NADP+ is reduced, they form NADPH.
  3. NADH oxidizes to form NAD+ as an oxidation reaction takes place; on the contrary, NADPH oxidizes to form NADP+ during their oxidation.
  4. NADH is involved in Cellular respiration processes that can take place in the absence of light; however, NADPH is involved in photosynthesis that takes place in the presence of light.
  5. NADH is used in the Electron transport chain to produce ATP by oxidative phosphorylation; however, NADPH is used in Calvin’s cycle to assimilate carbon dioxide.
  6. NADH is produced in glycolysis and Kerb’s cycle; on the flip side, NADPH is produced in light reaction of photosynthesis.
  7. NADH does not contain a free phosphate group; on the other hand, NADPH contains a free phosphate group attached to adenine moiety in 2’ position of ribose.
  8. NADH is involved mainly in catabolic reactions only, whereas NADPH is involved in anabolic reactions.
  9. NAD+ is the most abundant form found compared to NADH; however, NADPH is the most abundant form which is found in the cells.

Conclusion

NADH is used in cellular respiration for driving anabolic reactions during the glycolysis and Krebs cycle to produce ATP via oxidative phosphorylation, whereas NADPH is used in photosynthesis for driving catabolic reactions during the Calvin cycle to assimilate carbon dioxide.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White