Category

NAD+ & Glutathione

Two cofactors rather than two signalling peptides, which is what sets this shelf apart from the rest of the longevity department. NAD+ and reduced L-glutathione are both consumed by the reactions they appear in, so the work on them concerns pool size and redox state rather than receptor occupancy — and the vial fills run one to two orders of magnitude larger than a peptide vial for the same reason.

NAD+ (663.43 g/mol, CAS 53-84-9) is a dinucleotide coenzyme: nicotinamide mononucleotide joined to adenosine monophosphate through a pyrophosphate bridge. It is the electron acceptor for several hundred dehydrogenases, but what puts it on this shelf is that the sirtuins, the PARP family and CD38 cleave it at its glycosidic bond and release nicotinamide — each turnover destroys a molecule rather than recycling it. A 500 mg vial is roughly 754 micromoles, which is the figure to start from when a buffer concentration matters. Solutions are acidic, hydrolyse at alkaline pH, and are buffered and used promptly.

L-glutathione (307.32 g/mol, CAS 70-18-8) is formally a peptide, but an unusual one: gamma-L-glutamyl-L-cysteinyl-glycine, where the first bond runs through the glutamate side chain rather than its alpha-carboxyl. That linkage is why ordinary peptidases leave it alone and why it is assembled enzymatically in two ATP-dependent steps instead of on the ribosome. The free cysteinyl thiol is the reactive centre and oxidises on standing to the GSSG disulfide dimer, so a GSH/GSSG ratio is only as good as how freshly the solution was made; stocked at 600 mg and 1500 mg. NAD+ is additionally stocked as 300 mg capsules and as thin-film strips, making it the one molecule here where a route comparison can be run without changing the compound. Its precursors NMN and nicotinamide riboside are filed under vitamins and cofactors.