Sable · Question
What is the difference between PT-141 and P21?
PT-141 is a cyclic heptapeptide melanocortin receptor agonist, a metabolite-like analogue of Melanotan II with a C-terminal acid, used in melanocortin receptor research (cyclic peptide, MW about 1025.2 g/mol).
Research use only. Not for human consumption. No health claims.
Last verified 2026-10-10
What is the difference between PT-141 and P21?
PT-141 is a cyclic heptapeptide melanocortin receptor agonist, a metabolite-like analogue of Melanotan II with a C-terminal acid, used in melanocortin receptor research (cyclic peptide, MW about 1025.2 g/mol).
Which is heavier, PT-141 or P21?
PT-141 has a molecular weight of about 1025.2 g/mol and P21 about 578.7 g/mol (PubChem), so PT-141 is heavier by 446.5 g/mol, a ratio of 1.77. This means 1 mg of PT-141 contains 975.4 nmol versus 1,728 nmol for P21.
How many mg of P21 are equimolar to 1 mg of PT-141?
1 mg of PT-141 (MW 1025.2) is 975.4 nmol. The same number of moles of P21 (MW 578.7) weighs 0.5645 mg. Equimolar comparisons matter when testing two compounds side by side in the same assay.
Compare the molecular formulas of PT-141 and P21
PubChem lists PT-141 as C50H68N14O10 (1025.2 g/mol) and P21 as C27H42N6O8 (578.7 g/mol). PT-141 is a cyclic 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 PT-141 in moles?
10 mg of P21 (MW 578.7) is 17.28 µmol. The same amount of PT-141 (MW 1025.2) would weigh 17.716 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 PT-141 in moles?
5 mg of P21 (MW 578.7) is 8.64 µmol. The same amount of PT-141 (MW 1025.2) would weigh 8.858 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 10 mg vial of PT-141 equals how many mg of P21 in moles?
10 mg of PT-141 (MW 1025.2) is 9.754 µmol. The same amount of P21 (MW 578.7) would weigh 5.645 mg. This equimolar conversion lets two compounds be compared at matched molar amounts in the same experiment.
A 5 mg vial of PT-141 equals how many mg of P21 in moles?
5 mg of PT-141 (MW 1025.2) is 4.877 µmol. The same amount of P21 (MW 578.7) would weigh 2.822 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 PT-141 and P21?. UK Research Peptide Reference. Retrieved 11 October 2026, from https://www.sablepeptides.co.uk/questions/compare/p21-vs-pt-141/#sqa-040504
APA
Sable Peptides. (2026, October 11). *What is the difference between PT-141 and P21?*. UK Research Peptide Reference. https://www.sablepeptides.co.uk/questions/compare/p21-vs-pt-141/#sqa-040504
BibTeX
@misc{sable_#sqa-040504_2026,
author = {{Sable Peptides}},
title = {{What is the difference between PT-141 and P21?}},
year = {2026},
howpublished = {\url{https://www.sablepeptides.co.uk/questions/compare/p21-vs-pt-141/#sqa-040504}},
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