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Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine nucleobase and the other, nicotinamide. NAD exists in two forms: an oxidized and reduced form, abbreviated as NAD + and NADH (H for hydrogen), respectively.
When sufficient oxygen is not present in the muscle cells for further oxidation of pyruvate and NADH produced in glycolysis, NAD+ is regenerated from NADH by reduction of pyruvate to lactate. [4] Lactate is converted to pyruvate by the enzyme lactate dehydrogenase. [3] The standard free energy change of the reaction is -25.1 kJ/mol. [6]
Cellular respiration is a vital process that occurs in the cells of all [[plants and some bacteria ]]. [ 2 ] [ better source needed ] Respiration can be either aerobic, requiring oxygen, or anaerobic; some organisms can switch between aerobic and anaerobic respiration.
NAD is commonly called by other names, including NAD+ or NADH. These are both forms of NAD — NAD+ is the positively charged form, which has lost an electron, and NADH is the neutral form which ...
Glycolysis is the metabolic pathway that converts glucose (C 6 H 12 O 6) into pyruvate and, in most organisms, occurs in the liquid part of cells (the cytosol). The free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide (NADH). [1]
The glycerol-3-phosphate shuttle is a mechanism used in skeletal muscle and the brain [1] that regenerates NAD + from NADH, a by-product of glycolysis. NADH is a reducing equivalent that stores electrons generated in the cytoplasm during glycolysis. NADH must be transported into the mitochondria to enter the oxidative phosphorylation pathway.
The two substrates of this enzyme are sn-glycerol 3-phosphate and NAD +, whereas its 3 products are glycerone phosphate, NADH, and H +. This enzyme belongs to the family of oxidoreductases , specifically those acting on the CH-OH group of donor with NAD + or NADP + as acceptor.
Nicotinamide adenine dinucleotide phosphate, abbreviated NADP [1] [2] or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NADPH as a reducing agent ('hydrogen source').