SS-31

SS-31, also traded as elamipretide, is a four-residue cationic peptide containing D-arginine and dimethyltyrosine. The unnatural residues make the raw material inputs a significant share of the cost, so unusually low quotes usually indicate substitution rather than efficient manufacture.

Because the peptide is strongly cationic, trifluoroacetate carry-over from purification is common and can represent several percent of the delivered mass. We ask for the counterion to be identified and quantified.

Typical related substances are D to L epimers at the arginine positions, mono-methylated tyrosine variants and trifluoroacetate carry-over.