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The Human Energy CenterFenton LeBon, MD • nanoNAD+™
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Molecular Purity
9 min read•Archived in NAD_Research_Packet.pdf (Sections 2-3) & Dallas2.json

The Hourglass Rate-Limiting Neck: PARP, Sirtuins, SARM1, and CD38

Under metabolic strain, four vital enzyme families fight for the same dwindling pool of NAD+. Understanding the rate-limiting neck of the cellular hourglass.

“Under stress, disease, or aging, all four systems compete for NAD+ simultaneously. This makes NAD+ the rate-limiting molecule in cellular protection and energy — the narrow center of the hourglass.”

— Dr. Fenton LeBon, MD, MBA

Core Scientific Takeaways

  • NAD+ is not merely an energy metabolite; it is consumed as a co-substrate by regulatory enzymes.
  • The PARP System governs DNA repair and prevents uncontrolled chromosomal mutations.
  • The Sirtuin System (SIRT1-7) silences inflammatory NF-κB and drives antioxidant enzymes like SOD.
  • SARM1 acts as the nervous system's tree surgeon, pruning dying axons to protect the network.
  • CD38 commands immune cell calcium cascades to hunt pathogens and abnormal cells.

The Four Pillar Systems Dependent on NAD+

While NAD+ is widely recognized as a redox cofactor (cycling between NAD+ and NADH during energy synthesis), it plays an equally profound role as an enzymatically consumed substrate. Four distinct enzyme complexes consume NAD+ continuously:

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1. The PARP System: DNA Integrity & Mutation Defense

Poly(ADP-ribose) polymerases (primarily PARP-1 and PARP-2) detect single- and double-strand DNA breaks. PARP cleaves NAD+ to build poly(ADP-ribose) chains that recruit DNA repair complexes. When NAD+ levels plummet, PARP enzymes are left without their essential partner; unopposed PARP activity is directly implicated in peripheral axonal neuropathy.

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2. The Sirtuin System (SIRT1–SIRT7): Master Epigenetic & Inflammatory Controllers

Sirtuins are NAD+-dependent class III histone deacetylases. SIRT1 deacetylates the p65 subunit of NF-κB, shutting down systemic inflammatory transcription. It additionally stimulates Superoxide Dismutase (SOD) and protects reduced glutathione reserves.

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3. The SARM1 System: The Neural Tree Surgeon

Located predominantly in neuronal axons, SARM1 converts NAD+ into cyclic ADP-ribose (cADPR). SARM1 prunes damaged neurites cleanly so they do not rot and drain energy from healthy neurons.

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4. The CD38 System: Immune Mobilization & Calcium Flux

Expressed on T cells, natural killer (NK) cells, and macrophages, CD38 hydrolyzes NAD+ to synthesize cyclic ADP-ribose, triggering calcium release required for immune cells to destroy pathogens and senescent cells.

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