Reta, reta/cagri, RETA10-0803. What the abbreviations on a PEP-RTA-3 label and lot code actually encode, and which parts are vendor shorthand rather than chemistry.
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C221H342N46O68 and 4731.2 g/mol. What a mass spectrum confirms about PEP-RTA-3 identity, what the charge-state envelope means, and what identity testing cannot rule out.
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Six degradation routes, each tied to one residue. Across 13 catalogue sequences the dominant route is not the one textbooks lead with.
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Freeze-drying is three stages, not one. What each does, why a cake collapses, and what the look of the powder can and cannot tell you.
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Sum the residue masses, add one water. That reproduces the published formula for 11 catalogue compounds exactly. The four it misses are the lesson.
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Deionized, distilled, Water for Injection, sterile water, bacteriostatic water, saline and bacteriostatic saline: what each is and which to use.
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Tandem MS reads a fragment ladder, Edman reads one residue at a time, amino acid analysis counts residues. What each proves and what a mass cannot.
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From horseshoe crab blood to recombinant factor C: the three LAL readouts, USP 85 and 86, and what a limit of 0.05 EU/mL on a certificate means.
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A280 only sees tryptophan, tyrosine and cystine. Most of this catalogue has none of them, so the reading is zero. What to use instead.
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Non-pyrogenic is an endotoxin limit, not sterility. What EU/mL means, how the LAL assay proves it, and the figure from a published Pepstral lot.
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KPV is lysine-proline-valine, the last three residues of alpha-MSH. CAS 67727-97-3, mass 342.43, and what a 10 mg certificate reports.
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Five Khavinson peptides differ by one or two residues; the sixth is an extract. Sequences, masses and certificate figures, side by side.
Read the post →The blog covers buying, handling and research-design questions as they come up. The evergreen material lives in the guides: reading a certificate of analysis, storage and stability, one research guide per compound and the glossary.
New posts publish to the RSS feed. Every post is written for laboratory research use only and links to the lot certificate for any product it mentions.
One email when a new certificate is published, when a sold-out compound is back, or when a new compound is added. About twice a month, nothing else.