Selank Acetate + DSIP - Sleep and Serenity

1 Identity

Fixed-ratio two-component article: two unmodified all-L peptide free acids co-lyophilized, one a heptapeptide and one a nonapeptide. No metal center, no acyl chain, no conjugate, no disulfide, no non-proteinogenic residue, no terminal cap on either component. The two components are Selank and DSIP, and each component's full identity lives on its own record and is cross-referenced from here rather than restated. so a search run only on the abbreviation misses it. and Selank + DSIP; the DSIP component is separately cataloged under the INN emideltide. This title does something almost no other blend title does - it names a salt form on one component - and the record credits it while stating the limit: acetate fixes the counterion species and not its stoichiometry, and Selank carries three basic sites.

Sequence

Per component, cross-referenced. Selank: H-Thr-Lys-Pro-Arg-Pro-Gly-Pro-OH, one-letter TKPRPGP, seven residues, free acid. DSIP: H-Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu-OH, one-letter WAGGDASGE, nine residues, free acid. Both carry a free alpha-amine and a free C-terminal acid; neither is acetylated, amidated or acylated at any position.

Molecular formula

Per component; a mixture has no combined formula and none is written. Selank C33H57N11O9 free base; mono-acetate C35H61N11O11, bis-acetate C37H65N11O13, tris-acetate C39H69N11O15. DSIP C35H48N10O15 free acid, the acetate properly written C35H48N10O15 . XC2H4O2 rather than with a guessed integer. Neither component contains sulfur, so no 34S contribution exists anywhere in the article and an unexplained sulfur signature is contamination rather than chemistry.

Average mass

Per component, on IUPAC 2021 abridged conventional atomic weights: Selank 751.887 free base, mono-acetate 811.939, bis-acetate 871.991, tris-acetate 932.043; DSIP 848.824 free acid. The counterion arithmetic is the largest error available in this article and it is on the face of the record: Selank has three basic sites - the N-terminal alpha-amine, the lysine epsilon-amine and the arginine guanidine - so acetate can run from one to three equivalents, and a lot weighed as the tris-acetate but specified against the free base is 19.3 percent short of the stated substance. Worked example at a nominal 10 plus 10 mg net-peptide fill, 20 mg total: 13.300 and 11.781 micromol, a 1.129 : 1.000 molar ratio out of a 1 : 1 mass ratio. No single blend molecular weight is printed; a mixture does not have one.

Monoisotopic mass

Per component, neutral: Selank 751.4341; DSIP 848.3301. Both are small enough to be observed singly and doubly protonated on one acquisition, which makes this one of the few fixed-ratio blends where a single MS method covers the whole article without a span demonstration. The two neutrals sit 96.90 Da apart and are never confusable.

Salt / variant note

(1) ratio: none standard; 1 : 1 by net peptide is a company nominal. (2) Selank salt: acetate is named on the title but its stoichiometry is not - mono 811.939, bis 871.991, tris 932.043 against a free base of 751.887, a 19.3 percent swing, which is why net peptide content and counterion content are both reported. (3) DSIP salt: acetate or trifluoroacetate, written with X rather than a guessed integer. (4) NOMENCLATURE: DSIP and emideltide are one molecule under two names, and both are resolved to a single identity in the catalog so that a search on either finds it. (5) N-acetyl and amidated Selank analogs are separate articles with their own records and are not this component.

2 Class & testing panel

Form

Fixed-ratio blend

Testing panel

P1 — panel definitionfor both components, run per component and never once for the vial. This is the simplest of the fixed-ratio blends: two small unmodified peptides, no metal, no chirality problem, no conjugate, no ambiguity of molecule under either name. The difficulty is confined to counterion arithmetic and to proving the ratio, so net peptide content, acetate content and the measured component ratio are the lines that carry the weight on the certificate

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists for each component, is graded on that component's record and is cross-referenced rather than restated. None of it is literature about this two-component mixture. No published study of the two components co-formulated at a fixed ratio, and no consensus specification for such a mixture, has been located - an absence of located evidence rather than a demonstration that none exists.

4 Storage & specification

Storage

Co-lyophilized solid in Type I amber glass with a PTFE-lined closure, in-pack desiccant, stored at -20 degrees C plus or minus 5 degrees C, desiccated and protected from light; a non-sterile laboratory chemical, no sterility claim, no injection format. Nitrogen headspace is specified but carries less weight here than on most co-lyophilized blends, and the reason is stated so that it is not treated as boilerplate: neither component contains a methionine, a cysteine or a tyrosine, so the classic oxidation pathways are absent, and the tryptophan in DSIP is the only photo-oxidizable residue in the vial - which is why light protection, not the inert blanket, is the controlling condition here.

Shelf life

Provisional 24 months at -20 degrees C plus or minus 5 degrees C from QA release, pending the company's own data; the blend runs its own protocol and inherits no component study. The compatibility question the study answers rather than assumes is whether DSIP's two carboxylic acid side chains and free C-terminus shift the microenvironment pH of a cake that also contains a peptide with three basic sites, and whether that moves either component's degradation rate. Stability-indicating attributes: per-component content, the measured ratio, DSIP aspartate-linked degradation and tryptophan oxidation, Selank diketopiperazine formation, water, acetate content and any new peak above 0.10 percent. Pulls at 0, 3, 6, 12, 18, 24 and 36 months.