Pancragen

1 Identity

Short-chain bioregulator (Khavinson peptide family). Synthetic linear tetrapeptide, all four residues L and proteinogenic, free N-terminal alpha-amino group and free C-terminal carboxylic acid, no acylation, no amidation, no cyclization, no disulfide, no metal. One basic side chain (Lys), two acidic side chains (Glu, Asp) and one indole (Trp), which is the only chromophore and the only oxidation-labile center in the molecule. and pancreatic tetrapeptide of the Khavinson short-peptide line. Not A synonym and not this article: Suprefort, the pancreas peptide-extract preparation from the same product family, which is a compositionally undefined organ extract on a different panel and is never sourced against this purchase specification. Also not synonyms, and each a separate article with a separate mass: Vesugen (KED) and Testagen (KEDG).

Sequence

H-L-Lys-L-Glu-L-Asp-L-Trp-OH (KEDW). Free N-terminal alpha-amino group, free C-terminal carboxylic acid, no acetylation, no amidation, no cyclization, no disulfide; all four residues L and proteinogenic. Supplied as the acetate salt; trifluoroacetate lots are rejected at incoming because residual trifluoroacetate interferes with the cell-culture work that is the article's declared laboratory research use. The sequence remains a supplier claim until MS/MS confirms the residue order on the first lot from every supplier and after any change of manufacturing site — and on this molecule that is not a formality, because all 24 permutations of Lys, Glu, Asp and Trp share one formula and one exact mass.

Molecular formula

C26H36N6O9 as the free peptide. Supplied as the acetate salt, which is not a fixed stoichiometry and is therefore specified as a percentage range rather than as a formula; the shipped mass is peptide plus acetate plus water, and no single formula describes the jar.

Average mass

576.607 Da (C26H36N6O9), on IUPAC 2021 abridged conventional atomic weights (C 12.011, H 1.008, N 14.007, O 15.999) from the formula and independently reconstructed residue-by-residue from KEDW; the two routes agree to the digit. 576.599 also circulates, and the difference is worth knowing: it is the same formula on the pre-2021 atomic-weight table (C 12.0107, H 1.00794, N 14.0067, O 15.9994), which returns 576.5988 exactly. Neither figure is wrong. This catalog standardizes on the IUPAC 2021 abridged table and states the basis on the face of every mass, so 576.607 is the printed figure and 576.599 is recorded as its older-table equivalent. The difference is 0.008 Da and it matters only because a mass given without the table it was built on has not said anything.

Monoisotopic mass

576.25438 Da neutral; [M+H]+ 577.26166; [M+2H]2+ m/z 289.13447; [M-H]- 576.24710. Identity window on [M+H]+ at plus or minus 5 ppm is plus or minus 0.0029 Da. These figures do not move with the atomic-weight table, because monoisotopic masses are built from nuclide masses.

Salt / variant note

The headline fact, and it is not a mass problem but a mass IMPOSSIBILITY: all 24 permutations of Lys, Glu, Asp and Trp carry the identical formula C26H36N6O9 and the identical 576.25438 monoisotopic mass, so accurate mass at any resolution establishes nothing whatever about residue order, and MS/MS or co-elution against a qualified standard is the only discriminator. The second trap is worse: a Glu-to-Gln misincorporation in KEDW gives C26H37N7O8, and the C-terminal amide KEDW-NH2 gives C26H37N7O8 as well — not merely isobaric but the same molecular formula, average 575.623, monoisotopic 575.27036, exactly 0.984 Da below parent, indistinguishable from each other by mass at any resolution and separable only by MS/MS. Near neighbors, all cheaper to make because none carries tryptophan: Vesugen (KED) C15H26N4O8, 390.393 / 390.17506, [M+H]+ 391.18234 — the des-Trp truncation, exactly 186.08 Da light, simultaneously the product of a failed final coupling and the easiest deliberate substitution; Testagen (KEDG) C17H29N5O9, 447.445 / 447.19653; Livagen (KEDA) C18H31N5O9, 461.472 / 461.21218; Epitalon (AEDG) C14H22N4O9, 390.349 / 390.13868 — and note that Vesugen at 390.17506 and Epitalon at 390.13868 are indistinguishable at nominal mass and separated by 0.0364 Da (93 ppm), so a certificate reading "MW 390" identifies neither; Vilon (KE) C11H21N3O5, 275.305; Chonluten (EDG) C11H17N3O8, 319.270; Pinealon (EDR) C15H26N6O8, 418.407; Cardiogen (AEDR) C18H31N7O9, 489.486, which sits one alanine from Pinealon. Tryptophan degradants: single oxidation at plus 15.995 Da and N-formyl-kynurenine at plus 31.990 Da, both of which move the 280 nm channel and neither of which moves a 214 nm purity number much. Second molecule under the same name: one seller offers "Pancragen" at 20 mg and describes it as a "research peptide complex", printing no sequence, no formula and no mass — which is how a compositionally undefined organ-extract preparation is described, not a defined tetrapeptide; Suprefort is that undefined article and is not interchangeable with this one. Salt axis: acetate as specified, 4.0-12.0 percent w/w, against trifluoroacetate, which is refused.

2 Class & testing panel

Form

Single article

Testing panel

P1 — panel definition

3 Primary sources & evidence

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

Published literature exists and it is single-center. It is overwhelmingly in Russian, from one institute in St Petersburg and its collaborators, and comprises in-vitro work in cell and tissue culture plus rodent studies, with a small number of English-language review articles by the same authors restating the same primary work. No independent replication outside that group has been identified. No controlled human trial of this tetrapeptide is registered on ClinicalTrials.gov, no Western regulatory agency has reviewed it, and no pharmacokinetic or formal toxicology package exists in the public domain. Literature volume by study type is printed at the head of the research page so a reader sees the size of the base before reading a word of it.

4 Storage & specification

Storage

White to pale-beige lyophilized powder, acetate salt, in amber glass vials with a nitrogen headspace and desiccant. Labeled condition -20 degrees C plus or minus 5 degrees C, desiccated, protected from light; the indole side chain is both photolabile and oxidation-prone, which is why amber glass and the nitrogen overlay are specification items and not packaging preferences. A single excursion to 2-8 degrees C of up to 30 days cumulative is permitted and is recorded on the lot record. Shipped on gel packs with a temperature logger, and the logger record is filed against the shipment. Non-sterile, no sterility claim, no stoppered-and-crimped injection format, no dose-shaped vial.

Shelf life

Provisional 24-month retest interval at -20 degrees C plus or minus 5 degrees C. Provisional, and it is replaced by this company's own three-lot ICH Q1A-format study — long-term at -20 degrees C, accelerated at 25 degrees C and 60 percent RH, with photostability under ICH Q1B option 2 — at the 12-month data point. The stability-indicating attributes are the tryptophan oxidation products at plus 15.995 and plus 31.990 Da tracked on the 280 nm channel, not total assay, because indole oxidation is the identified degradation pathway on this molecule and a 214 nm assay barely sees it. Until that data exists the interval is a defensible engineering assumption and not a measurement, and the catalog says so. The interval is shortened on data and never extended without a completed dataset.