Is a linear sequence the same as a purity result?

No. The sequence is the residue order used for a calculation. Purity is the area percent when the report includes one.

Does the absence of cysteine prove there is no other ring?

It rules out an intramolecular cystine bridge in that string. Other end-to-end modifications still have to be read from the lot file, not assumed.

Glossary · 2026-09-24

Scientific lead: Alice Kay, Ph.D.

Linear peptide, laboratory definition

A linear peptide is an open chain of residues, written from the N-terminus to the C-terminus, without a ring implied by the string itself. Epithalon is catalogued as Ala-Glu-Asp-Gly on the 10 mg listing. BPC-157 is published as GEPPPGKPADDAGLV, with no cysteine, on What is BPC-157? and the 10 mg listing.

Calling a string linear does not replace a mass match. A later lot file could still name a modified species. Do not add a ring, an amide, or a salt that the PDF does not name. Compare language is on BPC-157 versus TB-500, which separates those sequences. Research-use only.

Frequently asked questions

Is a linear sequence the same as a purity result?: No. The sequence is the residue order used for a calculation. Purity is the area percent when the report includes one.
Does the absence of cysteine prove there is no other ring?: It rules out an intramolecular cystine bridge in that string. Other end-to-end modifications still have to be read from the lot file, not assumed.

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