Triphosphopyridine nucleotide
[CAS# 53-59-8]

Identification

• Classification: Biochemical >> Enzymes and coenzymes
• Name: Triphosphopyridine nucleotide
• Synonyms: beta-Nicotinamide adenine dinucleotide phosphate; beta-NADP
• Molecular Formula: C₂₁H₂₈N₇O₁₇P₃
• Molecular Weight: 743.41
• CAS Registry Number: 53-59-8
• EC Number: 200-178-1
• SMILES: C1=CC(=C[N+](=C1)[C@H]2[C@@H]([C@@H]([C@H](O2)COP(=O)([O-])OP(=O)(O)OC[C@@H]3[C@H]([C@H]([C@@H](O3)N4C=NC5=C(N=CN=C54)N)OP(=O)(O)O)O)O)O)C(=O)N

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319

Discovery and Applications

Triphosphopyridine nucleotide, commonly known as nicotinamide adenine dinucleotide phosphate (NADP⁺), is a crucial coenzyme involved in numerous biochemical redox reactions. It is structurally related to nicotinamide adenine dinucleotide (NAD⁺) but contains an additional phosphate group attached to the 2'-hydroxyl of the adenosine ribose moiety, distinguishing it functionally and structurally.

Discovered in the early 20th century during investigations into enzymatic oxidation-reduction processes, NADP⁺ was identified as a key cofactor in anabolic reactions, including lipid and nucleic acid biosynthesis. Its role complements that of NAD⁺, which is predominantly involved in catabolic pathways. The coenzyme exists in two forms: the oxidized form NADP⁺ and the reduced form NADPH, the latter serving as a major cellular reducing agent.

In cells, NADP⁺ participates primarily as an electron acceptor in oxidation-reduction reactions catalyzed by dehydrogenase enzymes. Upon accepting electrons, NADP⁺ is reduced to NADPH, which in turn donates electrons in biosynthetic reactions, such as fatty acid synthesis, cholesterol synthesis, and the detoxification of reactive oxygen species via glutathione reductase. NADPH also plays a vital role in maintaining the cellular redox state and supporting antioxidant defenses.

Biosynthetically, NADP⁺ is formed from NAD⁺ by phosphorylation through the action of NAD kinase enzymes, which transfer a phosphate group from ATP to the 2'-hydroxyl of the adenine-associated ribose. This conversion allows the cell to maintain distinct pools of NAD⁺ and NADP⁺, thereby regulating their specific participation in metabolic pathways.

The molecular structure of triphosphopyridine nucleotide includes two nucleotides linked via their phosphate groups: one containing adenine and the other nicotinamide. The nicotinamide moiety is the redox-active site where hydride transfer occurs. The triphosphate portion, including the additional phosphate in NADP⁺, influences enzyme binding specificity.

Analytical methods for studying NADP⁺ and NADPH include spectrophotometric assays based on their distinct absorbance spectra, with NADPH showing characteristic absorption at 340 nm. High-performance liquid chromatography (HPLC) and mass spectrometry (MS) provide further quantitative and qualitative analysis in biological samples.

In summary, triphosphopyridine nucleotide (NADP⁺) is an essential coenzyme serving as an electron carrier in anabolic reactions and antioxidant defense. Its unique structural feature, the additional phosphate group, differentiates its functional role from NAD⁺ and allows cells to finely regulate redox reactions critical for metabolism and cellular homeostasis.

References

1991. Atomic Structure of Ferredoxin-NADP + Reductase: Prototype for a Structurally Novel Flavoenzyme Family. Science (New York, N.Y.), 251(4989).
DOI: 10.1126/science.1986412

1990. Analysis of the kinetic mechanism of halophilic NADP-dependent glutamate dehydrogenase. Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1036(3).
DOI: 10.1016/0167-4838(90)90289-r

1979. Purification and characterization of mouse glucose 6-phosphate dehydrogenase. Molecular and Cellular Biochemistry, 24(3).
DOI: 10.1007/bf00314887