Sable · Question
What is the difference between SS-31 and P21?
SS-31 is a mitochondria-targeted tetrapeptide (Szeto-Schiller peptide) that associates with cardiolipin in the inner mitochondrial membrane, studied in mitochondrial bioenergetics research (peptide, MW about 639.8 g/mol).
Research use only. Not for human consumption. No health claims.
Last verified 2026-10-10
What is the difference between SS-31 and P21?
SS-31 is a mitochondria-targeted tetrapeptide (Szeto-Schiller peptide) that associates with cardiolipin in the inner mitochondrial membrane, studied in mitochondrial bioenergetics research (peptide, MW about 639.8 g/mol).
Which is heavier, SS-31 or P21?
SS-31 has a molecular weight of about 639.8 g/mol and P21 about 578.7 g/mol (PubChem), so SS-31 is heavier by 61.1 g/mol, a ratio of 1.11. This means 1 mg of SS-31 contains 1,563 nmol versus 1,728 nmol for P21.
How many mg of P21 are equimolar to 1 mg of SS-31?
1 mg of SS-31 (MW 639.8) is 1,563 nmol. The same number of moles of P21 (MW 578.7) weighs 0.9045 mg. Equimolar comparisons matter when testing two compounds side by side in the same assay.
Compare the molecular formulas of SS-31 and P21
PubChem lists SS-31 as C32H49N9O5 (639.8 g/mol) and P21 as C27H42N6O8 (578.7 g/mol). SS-31 is a peptide; P21 is a peptidomimetic. These formulas refer to the parent compounds without salt counter-ions.
A 10 mg vial of P21 equals how many mg of SS-31 in moles?
10 mg of P21 (MW 578.7) is 17.28 µmol. The same amount of SS-31 (MW 639.8) would weigh 11.056 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 5 mg vial of P21 equals how many mg of SS-31 in moles?
5 mg of P21 (MW 578.7) is 8.64 µmol. The same amount of SS-31 (MW 639.8) would weigh 5.528 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 5 mg vial of SS-31 equals how many mg of P21 in moles?
5 mg of SS-31 (MW 639.8) is 7.815 µmol. The same amount of P21 (MW 578.7) would weigh 4.523 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 10 mg vial of SS-31 equals how many mg of P21 in moles?
10 mg of SS-31 (MW 639.8) is 15.63 µmol. The same amount of P21 (MW 578.7) would weigh 9.045 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A CoA for every lot; each vial carries a printed lot number that matches it. Ask with the lot number and we send it.
Cite this
Research use only. Not for consumption. No health claims.
Plain
Sable Peptides. (2026). What is the difference between SS-31 and P21?. UK Research Peptide Reference. Retrieved 11 October 2026, from https://www.sablepeptides.co.uk/questions/compare/p21-vs-ss-31/#sqa-040658
APA
Sable Peptides. (2026, October 11). *What is the difference between SS-31 and P21?*. UK Research Peptide Reference. https://www.sablepeptides.co.uk/questions/compare/p21-vs-ss-31/#sqa-040658
BibTeX
@misc{sable_#sqa-040658_2026,
author = {{Sable Peptides}},
title = {{What is the difference between SS-31 and P21?}},
year = {2026},
howpublished = {\url{https://www.sablepeptides.co.uk/questions/compare/p21-vs-ss-31/#sqa-040658}},
note = {Accessed 11 October 2026. CC BY 4.0}
}Badge
<a href="https://www.sablepeptides.co.uk/ref"><img src="https://www.sablepeptides.co.uk/badge/ref.svg" alt="Data: UK Research Peptide Reference — Sable Peptides" width="220" height="40"></a>
Date modified: 2026-10-10