Nicotinamide adenine dinucleotide

Nicotinamide adenine dinucleotide (NAD) is a <a href="/facts/Cofactor_(biochemistry)/AGo0PCUU">coenzyme</a> central to <a href="/facts/Metabolism/WxDrm8k5">metabolism</a>. Found in all living <a href="/facts/Cell_(biology)/bLM9UQvy">cells</a>, NAD is called a dinucleotide because it consists of two <a href="/facts/Nucleotide/pQKEwlJI">nucleotides</a> joined through their <a href="/facts/Phosphate/FDGVCxUG">phosphate</a> groups. One nucleotide contains an <a href="/facts/Adenine/PSeDFBnl">adenine</a> <a href="/facts/Nucleobase/zj1Vl9Qh">nucleobase</a> and the other, <a href="/facts/Nicotinamide/5GQcLC5K">nicotinamide</a>. NAD exists in two forms: an <a href="/facts/Redox/Pyd5RVcj">oxidized and reduced</a> form, abbreviated as NAD+ and NADH (H for <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a>), respectively.
In cellular metabolism, NAD is involved in redox reactions, carrying <a href="/facts/Electron/L0KBo5cW">electrons</a> from one reaction to another, so it is found in two forms: NAD+ is an <a href="/facts/Oxidizing_agent/1FQzB8pQ">oxidizing agent</a>, accepting electrons from other molecules and becoming reduced; with H+, this reaction forms NADH, which can be used as a <a href="/facts/Reducing_agent/CtfSGVXC">reducing agent</a> to donate electrons. These <a href="/facts/Electron_transfer/BIdASS9R">electron transfer</a> reactions are the main function of NAD. It is also used in other cellular processes, most notably as a <a href="/facts/Substrate_(biochemistry)/6MnaV19h">substrate</a> of <a href="/facts/Enzyme/DSI1Fh7y">enzymes</a> in adding or removing <a href="/facts/Chemical_group/GXkSPsjM">chemical groups</a> to or from <a href="/facts/Protein/Jxmagu3E">proteins</a>, in <a href="/facts/Posttranslational_modification/KMUayTIc">posttranslational modifications</a>. Because of the importance of these functions, the enzymes involved in NAD metabolism are targets for <a href="/facts/Drug_discovery/LLdDNvjy">drug discovery</a>.
In organisms, NAD can be <a href="/facts/Organic_synthesis/WLFePEzH">synthesized</a> from simple building-blocks (<a href="/facts/De_novo_synthesis/mDEr4L0K">de novo</a>) from either <a href="/facts/Tryptophan/JcUxlxAh">tryptophan</a> or <a href="/facts/Aspartic_acid/9DFSFPa1">aspartic acid</a>, each a case of an <a href="/facts/Amino_acid/WDxYwBny">amino acid</a>. Alternatively, more complex components of the coenzymes are taken up from nutritive compounds such as <a href="/facts/Nicotinic_acid/UAAqPpk6">nicotinic acid</a>; similar compounds are produced by reactions that break down the structure of NAD, providing a <a href="/facts/Salvage_pathway/Qzd8RKwv">salvage pathway</a> that recycles them back into their respective active form.
In the name NAD+, the <a href="/facts/Subscript_and_superscript/6tExBnkw">superscripted</a> plus sign indicates the positive <a href="/facts/Formal_charge/uqHf9WD7">formal charge</a> on one of its nitrogen atoms.
A biological coenzyme that acts as an electron carrier in enzymatic reactions.
Some NAD is converted into the coenzyme <a href="/facts/Nicotinamide_adenine_dinucleotide_phosphate/BHdLW925">nicotinamide adenine dinucleotide phosphate</a> (NADP), whose chemistry largely parallels that of NAD, though its predominant role is as a coenzyme in <a href="/facts/Anabolic/eH3Q5AHF">anabolic</a> metabolism.
NADP is a reducing agent in anabolic reactions like the Calvin cycle and lipid and nucleic acid syntheses. NADP exists in two forms: NADP+, the oxidized form, and NADPH, the reduced form. NADP is similar to nicotinamide adenine dinucleotide (NAD), but NADP has a phosphate group at the C-2′ position of the adenosyl.

Nicotinamide adenine dinucleotide open-in-new

Nicotinamide adenine dinucleotide