NADH is the abbreviation for “nicotinamide adenine dinucleotide hydrogen,” which is a molecule that plays an important role in the energy metabolism of cells. This molecule is the reduced form of a coenzyme called nicotinamide adenine dinucleotide (NAD+).
NADH releases high-energy electrons as it travels along the electron transport chain, contributing to the synthesis of ATP, the energy molecules. Therefore, NADH plays a critical role in meeting the energy needs of cells.
Free radicals, or more precisely oxygen free radicals, are unstable toxic compounds that are produced during metabolism in the body. If these compounds are not eliminated by antioxidants, they can easily cause damage to tissues, leading to potentially fatal consequences.
This molecule also possesses antioxidant properties. It can help reduce oxidative stress in cells and prevent cellular damage. The antioxidant effects of NADH are achieved through the neutralization of free radicals and the preservation of normal cellular functions.
In cells, NADH is produced during the oxidation of nutrients. The molecule is then transported to energy-producing regions within the cell, such as the mitochondria, where it releases electrons and contributes to ATP synthesis. ATP is the fundamental energy molecule in cellular energy transport and utilization processes.
NADH is an important electron carrier in redox reactions. It catalyzes oxidation and reduction processes by transferring electrons in many biochemical reactions. These reactions play a critical role in the regulation of cellular metabolism, digestion of nutrients, biosynthesis, and other metabolic processes.
NADH also affects cell cycle and signal transmission, playing a role in the regulation of cell division, growth, and the modulation of gene expression.
Balanced levels of NADH are important for healthy metabolic function. Deficiencies or imbalances of this molecule have been associated with energy metabolism disorders, neurodegenerative diseases, oxidative stress, and other health issues.
In cells, NADH is produced during the oxidation of nutrients and participates in a series of reactions in energy metabolism. Some chemical events that explain the role of this molecule in energy metabolism are as follows:
Cellular Respiration: In energy-producing regions of cells such as mitochondria, NADH transfers its electrons to the electron transport chain. These electrons are transported through proteins in the electron transport chain, resulting in the synthesis of ATP along with the release of free energy. This process is called oxidative phosphorylation and is the main mechanism of energy production.
Glycolysis: In a metabolic pathway called glycolysis, glucose molecules are broken down to produce ATP and NADH. During the oxidation of glucose, NAD+ molecules are reduced to NADH. This molecule is then transported to the mitochondria and participates in cellular respiration.
Krebs Cycle: NADH acts as an electron carrier in the Krebs cycle (also known as the citric acid cycle) and participates in oxidation reactions throughout this cycle, producing more NAD+. These reactions release free energy and synthesize a series of intermediate products.
Beta Oxidation: NADH is produced during the oxidation of fatty acids. In a process called beta oxidation, fatty acids are broken down to acetyl-CoA, resulting in the production of NADH. Acetyl-CoA then enters the Krebs cycle and contributes to the production of this molecule.
These effects of NADH on energy metabolism allow it to play a critical role in meeting the energy needs of cells and contributing to ATP synthesis. Its role as an electron carrier in oxidation-reduction reactions regulates cellular energy production processes and maintains energy balance.
References:
Xie, N., Zhang, L., Gao, W. et al. NAD+ metabolism: pathophysiologic mechanisms and therapeutic potential. Sig Transduct Target Ther 5, 227 (2020). https://doi.org/10.1038/s41392-020-00311-7
Free Radicals and Antioxidant Vitamins Optimizing the Health of the Athlete Laursen, Paul B. MSc Strength and Conditioning Journal 23(2):p 17, April 2001.
Yuan, X., Liu, Y., Bijonowski, B.M. et al. NAD+/NADH redox alterations reconfigure metabolism and rejuvenate senescent human mesenchymal stem cells in vitro. Commun Biol 3, 774 (2020). https://doi.org/10.1038/s42003-020-01514-y
Role of NAD+ in regulating cellular and metabolic signaling pathways. Sara Amjad, Sabah Nisar, Ajaz A Bhat, Metab. 2021 Jul:49:101195. doi: 10.1016/j.molmet.2021.101195. Epub 2021 Feb 17.
Xie, N., Zhang, L., Gao, W. et al. NAD+ metabolism: pathophysiologic mechanisms and therapeutic potential. Sig Transduct Target Ther 5, 227 (2020). https://doi.org/10.1038/s41392-020-00311-7
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