A peptide can be short and still need a detailed structural description. SS-31 is a useful example: counting four residues does not tell a calculator everything it needs to know. A nonstandard residue and the terminal group matter too.
Start with the complete structure
PubChem lists the sequence description H-D-Arg-Tyr(2,6-diMe)-Lys-Phe-NH2 for compound 11764719. The modified tyrosine is often abbreviated Dmt. Here, Dmt means 2,6-dimethyltyrosine; it is not ordinary tyrosine. The D-Arg notation and the amide end also belong to the specification. [1]
Check what the calculator can represent
Typing an ordinary four-letter amino-acid string cannot fully describe that structure. A suitable calculation needs to account for the nonstandard residue, terminal amidation and residue configuration. Do not assume that an unfamiliar letter or a note beside the input will change the calculation. Check the tool’s supported notation first.
Use reference numbers with their meaning attached
For the neutral structure in that PubChem record, the molecular formula is C32H49N9O5 and the computed molecular weight is 639.8 g/mol. These are reference structure values, not the amount of peptide in a supplied vial. A counterion, water or a different supplied form can change the meaning of a powder-based calculation. [1]
What to send with an enquiry
Send the full structure description rather than a short name alone. Ask which molecular form is proposed, which mass value is used and what identity evidence could be provided. The NHD SS-31 family page is a starting point for a research-material enquiry; it does not establish a particular lot’s identity or quantity.
Useful links
For laboratory research, development and manufacturing only. Not for human or veterinary use.
Sources and examples
Reference records explain the topic; they do not establish NHD stock, a supplied lot’s results or clinical suitability. Examples explicitly labeled as hypothetical are calculations, not test data.
Sources & editorial method
AI-assisted drafting, source checks, translation and generated comic illustration. This is not independent peer review or supplied-lot verification.
1 linked records are listed in the references below. Read the editorial and AI-assistance policy.
How to interpret this article
Reference data and teaching examples are separated from NHD lot results; product specifications and availability require confirmation.
Research-use boundary: Catalog materials discussed on this website are for laboratory research, development and manufacturing use only, not for human or veterinary use. This content is not medical advice and does not provide administration instructions.
Primary records and authoritative sources
- PubChem: compound 11764719PubChem: compound 11764719. Accessed 2026-10-03.
