NA Semax

NA Semax (N-acetyl Semax, Ac-Semax) is the N-terminally acetylated analog of Semax, the synthetic heptapeptide derived from the ACTH(4-10) fragment of adrenocorticotropic hormone. By blocking the free N-terminal amine through acetylation, NA Semax preserves the parent sequence while modifying both its metabolic profile and its coordination chemistry. It is classified as a chemically stabilized synthetic neuropeptide analog studied in parallel with native Semax across neurotrophic, neuropeptidergic, and metal-binding research models.

The mechanism of action of NA Semax is closely related to that of Semax, with several distinguishing features attributable to the N-acetyl modification. Acetylation of the N-terminal methionine residue increases resistance to aminopeptidase-mediated cleavage in plasma and tissue homogenates, extending the functional half-life of the peptide in laboratory preparations. The modification also alters the metal-binding behavior of the molecule: the free alpha-amino group present in native Semax serves as a primary anchoring site for transition metal ions such as Cu(II) and Zn(II), and its removal in NA Semax shifts coordination toward the imidazole nitrogen of histidine and other backbone donor atoms. Research has shown that this restructuring of the metal-binding geometry modifies copper-binding affinity and stoichiometry, with downstream consequences for redox behavior and receptor-level interactions in the melanocortin and neurotrophic-signalling pathways studied for the parent compound.

Research interest in NA Semax peptide spans plasma stability and proteolytic-degradation profiling, transition-metal coordination chemistry of ACTH-derived neuropeptides, comparative receptor and neurotrophic signaling against native Semax, and adaptive-signalling responses in central nervous system tissue models. A detailed coordination-chemistry analysis demonstrated that N-terminal acetylation profoundly alters the copper-binding properties of Semax, with measurable consequences for its biological activity in laboratory models (Magrì et al., 2016, Journal of Inorganic Biochemistry). These findings have established NA Semax as a useful research tool for dissecting the contributions of N-terminal chemistry to neuropeptide function and for studying chemically stabilized ACTH(4-10) analogs alongside the parent molecule.

For background on the parent peptide, see our Semax vs Selank comparison.

The peptide is supplied as a lyophilized powder to ensure optimal stability during storage and handling.

The ACTH(4-10) fragment has been a focal point of neuropeptide research since the late twentieth century, when investigators at the Institute of Molecular Genetics of the Russian Academy of Sciences developed Semax as a Pro-Gly-Pro-extended heptapeptide intended to retain the neurotropic activity of the parent fragment while removing its endocrine signaling at the adrenal cortex. Subsequent research extended the focus from the native sequence to a series of chemically modified analogs, including N-acetylated, C-amidated, and metal-loaded forms designed to probe the structural determinants of peptide stability and activity.

NA Semax was developed within this analog program as a derivative in which the free N-terminal amine of methionine is acetylated. This modification eliminates a primary site of aminopeptidase recognition and simultaneously removes a key metal-coordinating group from the molecule. Comparative chemistry and biology studies of Ac-Semax versus Semax have characterized the resulting changes in plasma stability, copper- and zinc-binding geometry, and downstream effects on neurotrophic and adaptive-signalling research endpoints.

NA Semax occupies a defined position in the Pepcore ACTH-analogue research catalog as a chemically stabilized counterpart to native Semax. It is studied alongside Semax 10 mg and other neuropeptide research tools in laboratories investigating ACTH-derived peptide chemistry, brain-targeted delivery research, and the role of N-terminal modifications in neuropeptide function.

1. Enhanced Proteolytic Stability

The N-terminal acetyl group on NA Semax shields the methionine alpha-amine from aminopeptidase recognition, an entry point for rapid degradation of native Semax in plasma and tissue preparations. Research models indicate that this modification extends the functional half-life of the peptide in laboratory matrices, allowing extended-duration experimental designs that are challenging with the parent sequence.

2. Modified Metal-Binding Chemistry

In native Semax, the free N-terminal amine of methionine acts as a primary anchoring group for transition metal ions such as Cu(II) and Zn(II). Acetylation of this amine in NA Semax redirects coordination toward the imidazole nitrogen of the histidine side chain and other backbone donor atoms, producing complexes with different stoichiometry, geometry, and redox behavior. These changes are investigated for their influence on copper-mediated signaling and oxidative-stress chemistry in neuropeptide research.

3. Neurotrophic and Neuropeptidergic Signalling

NA Semax retains the core ACTH(4-10) sequence and is studied within the same neurotrophic and neuropeptidergic research framework as Semax. Comparative experiments examine its influence on BDNF and NGF expression, melanocortin-system interactions, and neurotransmitter balance in cultured neural cells and rodent brain tissue, with attention to how the N-acetyl modification reshapes these readouts.

4. Adaptive-Signalling and Stress-Response Research

Like its parent compound, NA Semax is examined in research models of cellular-stress responses in central nervous system tissue, including hypoxia, oxidative stress, and excitotoxic signaling. The combination of extended stability and modified metal-binding behavior positions NA Semax as a research tool for dissecting which features of Semax activity depend on N-terminal chemistry and which depend on the intact heptapeptide backbone.

Research Applications

Conclusion

NA Semax is a chemically stabilized analog of Semax in which N-terminal acetylation extends proteolytic resistance and reshapes transition-metal coordination chemistry. Through its modified stability profile and altered metal-binding behavior, NA Semax serves as a research tool for investigating how N-terminal chemistry contributes to ACTH(4-10) neuropeptide function and for comparative studies alongside the parent molecule.

Research Use Disclaimer

This product is intended for research and laboratory use only. It is designed exclusively for in vitro research purposes. All information provided is for educational and research reference only. This product is not intended for human or animal use. It is not a drug, food, or cosmetic and must not be marketed, labeled, or used as such. Use and handling are restricted to trained and qualified professionals.