MOTS-C 20mg Peptide

Concentration at each diluent volume

20 mg of dry material reaches these concentrations in the volumes below. The figures are a unit conversion for preparing a laboratory stock solution, not a quantity to use.

MOTS-C by the milligram

The same compound in every strength the catalogue carries, priced per milligram of material so the vials are comparable. Larger is not automatically cheaper.

The 20mg vial is the cheapest material in this range at $2.60 per mg, which is this page.

Per-unit figures are quoted in US and Canadian dollars so the vials stay comparable against each other. The price you are charged is the one in the currency selected at the top of the page, and it is converted from the same US dollar base as the figures here.

Identity by mass: the ions to expect

An electrospray source protonates the molecule rather than weighing it neutral, so a spectrum shows a series of charge states rather than the molecular weight itself. These are the m/z values 2,174.6 g/mol produces, and they are what a mass spectrum on a certificate for MOTS-C has to match.

A peptide this size is normally reported at its doubly and triply charged states, and the singly charged ion may not appear at usable intensity at all. A spectrum showing only one of these is not a failed identity check.

What a certificate for MOTS-C should carry

A purity percentage on its own is not checkable. These are the entries that make one verifiable, and their absence is the most common weakness in a research-peptide certificate.

• The chromatogram, not only the number

  A stated area percent with no trace behind it cannot be read for the shape of the main peak or for what eluted beside it. The HPLC interpreter walks through what a trace shows.

• Net peptide content, separately from gross mass

  A lyophilised peptide is a salt, usually of trifluoroacetic or acetic acid, plus residual water. The vial's stated milligrams are gross; net peptide content is the fraction of that mass which is the molecule. The two differ by ten to twenty percent routinely, and only one of them is what the price is per milligram of. The net peptide content calculator converts between them.

• The counterion, named

  Which salt form the powder is in changes the net content and the pH the powder dissolves at. A certificate that never names it leaves both unknowable.

• Water content, by a stated method

  Loss on drying and Karl Fischer water determination give different numbers, and a water figure with no method attached cannot be compared with anyone else's.

• A laboratory and a report identifier

  Without both, nothing on the document can be traced back to the laboratory that issued it. The red flag checker lists the rest.

What degrades this compound

Each of these follows from the molecule itself rather than from general peptide handling.

• Oxidation

  2 Met and 1 Trp

  These side chains oxidise on contact with dissolved oxygen and with peroxide traces in diluents. Oxidation adds 16 daltons per event, so it shows up on a mass spectrum as a satellite peak above the parent and on a chromatogram as a shoulder ahead of the main peak. Minimise headspace air, and do not use a diluent that has been standing open.

• Deamidation

  1 Gln

  Asparagine and glutamine lose their side-chain amide in aqueous solution, becoming aspartate and glutamate. The product is one dalton heavier and one charge more acidic, which moves its retention time without changing its size much, so it reads as an extra peak rather than a smaller one. No asparagine here is followed by glycine, serine or histidine, the three neighbours that accelerate the reaction, so the rate is the slower baseline one.

• Light sensitivity

  1 Trp and 2 Tyr

  The aromatic side chains that make this compound visible at 280 nm are the same ones that absorb ultraviolet light and photo-oxidise. This is the residue-level reason behind the instruction to store in the dark, and it is why an amber vial is not decoration.

What holds up

The degradation routes this compound is not exposed to, which is as specific a fact as the ones it is.

• Net hydrophilic

  GRAVY -0.94

  A negative grand average of hydropathy means the side chains are on balance polar, which is the profile that stays in solution rather than associating. Freeze-thaw cycles are still worth avoiding, but this compound is not one of the hydrophobic sequences that aggregate irreversibly at an ice front.

• Solubility window

  calculated pI 10.6, net charge 3 at pH 7

  A peptide is least soluble within about a pH unit of its isoelectric point, where it carries no net charge. This one is far enough from neutral that it holds a real charge in an ordinary diluent, which is what keeps it dissolved.