AHK-Cu (Copper Tripeptide-3) vs NAD+ (Nicotinamide Adenine Dinucleotide)

AHK-Cu (Copper Tripeptide-3)

AHK-Cu is a copper(II) complex of the synthetic tripeptide alanyl-histidyl-lysine, a close relative of the naturally occurring GHK-Cu. The two differ only in the first residue: alanine here, glycine in GHK. GHK is found in human plasma and has a long history in the literature as a copper-binding peptide; AHK is a synthetic variant with the histidine in the same position. Published work on AHK-Cu is small and mostly in vitro, using cultured human dermal papilla cells and fibroblasts, and isolated hair follicles kept alive in organ culture. Controlled human studies are scarce, and much of the wider discussion of the compound borrows from GHK-Cu rather than from data on AHK-Cu itself.

NAD+ (Nicotinamide Adenine Dinucleotide)

NAD+, nicotinamide adenine dinucleotide, is a non-peptide coenzyme formed from two nucleotides joined through their phosphate groups. One nucleotide carries adenine and the other nicotinamide, a form of vitamin B3, and the molecule occurs in every living cell. Cells can make it from tryptophan or nicotinic acid, but mammalian cells rely mostly on a salvage pathway that recycles nicotinamide, with the enzyme NAMPT setting its pace. Identified in yeast extracts more than a century ago, it has long been central to enzymology; recent work, mostly in rodents and cell culture, concerns its roles in signalling and how its levels change with age and metabolic state. Human data on exogenous NAD+ remain limited.

How AHK-Cu (Copper Tripeptide-3) acts

In GHK-Cu, the copper ion is held by the N-terminal amine, the deprotonated amide nitrogen between the first two residues and a nitrogen of the histidine imidazole ring. AHK is thought to bind copper in the same way, since its histidine sits in the same position. Copper-peptide complexes of this kind have been studied as carriers that deliver copper, a cofactor for enzymes such as lysyl oxidase and superoxide dismutase, to cells. In cultured human dermal papilla cells, AHK-Cu has been reported to affect cell proliferation and markers of apoptosis, including the balance of Bcl-2 and Bax. Which receptors or transporters mediate these observations has not been established.

How NAD+ (Nicotinamide Adenine Dinucleotide) acts

NAD+ accepts a hydride ion to become NADH, and the NAD+/NADH pair carries electrons from glycolysis and mitochondrial dehydrogenases to complex I of the respiratory chain. Beyond this redox role, three enzyme families consume NAD+ as a substrate: the sirtuins, which remove acetyl and other acyl groups from proteins; the poly(ADP-ribose) polymerases (PARPs), which are activated by DNA strand breaks; and CD38 and related enzymes, which generate signalling molecules such as cyclic ADP-ribose. NAD+ outside cells is generally thought to be broken down by cell-surface enzymes into smaller precursors before cells take it up, so the fate of exogenous NAD+ is itself a research question.

The records side by side

• Type: AHK-Cu (Copper Tripeptide-3), Copper tripeptide complex; NAD+ (Nicotinamide Adenine Dinucleotide), Coenzyme (dinucleotide)
• Length: AHK-Cu (Copper Tripeptide-3), 3 amino acids; NAD+ (Nicotinamide Adenine Dinucleotide), not recorded
• Molecular weight: AHK-Cu (Copper Tripeptide-3), 451.39 g/mol; NAD+ (Nicotinamide Adenine Dinucleotide), 663.4 g/mol
• Molecular formula: AHK-Cu (Copper Tripeptide-3), C15H24ClCuN6O4-; NAD+ (Nicotinamide Adenine Dinucleotide), C21H27N7O14P2

Reading a comparison

A comparison places two records side by side; it does not merge them. Each description above is drawn from that compound's own record, and the two were not necessarily characterised by the same methods, at the same time, or to the same level of detail. Before comparing any attribute, it is worth establishing that both records describe the substance you think they describe — names are not identifiers, and two entries sharing a name can differ in salt form, stereochemistry or the convention used to state a mass. Where a figure carries no method beside it, the comparison is between two reported numbers rather than between two measurements.