MOTS-c: structure and analysis

What it is

MOTS-c is a 16-amino-acid peptide encoded in the mitochondrial genome rather than the nuclear one — one of a small group of mitochondrial-derived peptides identified over the past two decades.

That genomic origin is what makes it unusual. Almost every peptide in this catalogue corresponds to a nuclear-encoded sequence or is entirely synthetic in design; this one is transcribed from mitochondrial DNA.

The sequence includes methionine and tryptophan residues, both of which have consequences for how the material behaves analytically.

How it is produced

Assembled by solid-phase peptide synthesis: the chain is built one residue at a time on an insoluble resin support, then cleaved from the resin, deprotected and purified — most commonly by reversed-phase high-performance liquid chromatography. The purified material is lyophilized to a dry solid.

The impurity profile that appears on a certificate is a record of where that process was imperfect: deletion sequences from an incomplete coupling, truncated chains, and species retaining a protecting group.

Confirming identity

Mass spectrometry confirms the sixteen-residue chain. At this length a single deletion produces a clear mass shift and is readily detected.

Because the sequence contains methionine, the corresponding sulfoxide is a species an identity method will encounter: oxidation adds sixteen mass units, which is unambiguous at high resolution.

Analytical considerations

Methionine oxidation is the characteristic impurity to expect. Methionine is among the most readily oxidised residues, and the sulfoxide product is a real and quantifiable impurity rather than a theoretical one — which is why a purity method for this compound needs to resolve it from the parent.

Tryptophan adds light sensitivity. It is the most photochemically labile of the standard amino acids, so light protection during storage is a reasonable precaution and photodegradation products are a plausible impurity class.

At sixteen residues the compound is well suited to reversed-phase separation: long enough to be properly retained, short enough that deletion products remain resolvable.

What its certificate reports

A certificate for a lot of this material names the lot, names the issuing laboratory, and states for each parameter both the method used and the specification the result was measured against. Identity and purity are the two core results; net peptide content states how much of the fill weight is actually peptide.

A certificate belongs to a lot, not to a product line. When a new lot is released it is tested again, and the certificate published against it is that lot's certificate — a previous lot's result is never carried forward.

Research use only

This page describes structure and analysis. It makes no claim about what this compound does, and none should be inferred from it. Material is supplied for laboratory research use only: it is not a drug, food, dietary supplement, cosmetic or medical device, it is not for human or veterinary consumption, and no dosing, administration or reconstitution guidance is provided for any such use.