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Peptide Research & Procurement Glossary
The vocabulary that decides whether a specification, a COA or a supplier claim actually means what it appears to mean. Entries state the limits of each term as well as its definition, because that is where procurement errors start.
Identity & analytics
Peptide
A chain of amino acids linked by peptide bonds. Short chains (roughly under 50 residues) are conventionally called peptides; longer ones are proteins. Research peptides are supplied as the defined synthetic sequence, not as a biological extract.
Amino acid sequence
The order of residues in the chain, written N-terminus to C-terminus. The sequence defines the molecule's mass and, in most cases, its receptor pharmacology — which is why a two-residue difference between two peptides is a real difference, not a labelling detail.
CAS Registry Number
A unique numeric identifier for a chemical substance, in the form NNN-NN-N. It identifies the substance, not the grade, the salt form or the supplier. Identity is only complete when the CAS number is read together with the stated salt/free-base form and purity method.
Molecular weight (Da / g·mol⁻¹)
The sum of atomic masses for the defined structure. For peptides it is reported as the monoisotopic or average mass; the two differ slightly, which matters when a COA is compared against a theoretical value.
Acetate salt / free base
The counter-ion form in which a peptide is supplied. The same peptide as an acetate salt and as a free base have different masses, so the form must be stated before masses are compared.
HPLC (high-performance liquid chromatography)
The standard separation technique used to measure peptide purity. Meaningful purity figures require the column, mobile phase, gradient and detection wavelength to be stated — “≥99% by HPLC” alone is not a complete method statement.
Peak area purity vs peptide content
Peak-area purity (the percentage of integrated UV signal) and net peptide content (the mass fraction that is actually peptide, measured by amino-acid analysis) are different quantities. A high purity percentage does not by itself mean a high content figure, which is why both belong on a COA.
ESI-MS (electrospray ionisation mass spectrometry)
The technique used to confirm that the synthesized molecule is the intended one, by comparing observed mass against the theoretical mass of the sequence — including the expected adducts.
Lyophilization
Freeze-drying: the peptide is supplied as a dry powder to slow degradation. It is the standard presentation for research peptides.
Handling & storage
Reconstitution
Dissolving the lyophilized powder in a solvent, usually sterile water, bacteriostatic water or buffer. Solubility and stability depend on the peptide, the pH and the ionic strength — the batch COA states the solvent tested.
Bacteriostatic water
Sterile water containing an antimicrobial preservative, used as a multi-dose laboratory diluent. Unpreserved sterile water is preferred where a preservative could interfere with the assay.
Aliquot
A single-use portion of a reconstituted solution, frozen separately so that a vial is thawed once only. Aliquoting is the standard practice for limiting freeze–thaw degradation.
Freeze–thaw cycle
One round of freezing and thawing. Repeated cycles are associated with aggregation and loss of activity for many peptides, which is the reason single-use aliquots are recommended.
Desiccated storage
Storage with a moisture-absorbing sachet, typically at 2–8 °C for lyophilized peptide and protected from light. Moisture uptake is one of the main degradation routes for lyophilized powders.
Pharmacology & research context
Receptor agonist
A compound that binds a receptor and activates it. A selective agonist activates one receptor subtype at the concentrations studied; a non-selective one activates several. In the GHRP family, selectivity is the property that separates the members.
Half-life
The time in which the circulating concentration of a compound falls by half. It determines whether a research protocol produces a discrete pulse or a sustained stimulus — the CJC-1295 forms differ by roughly three orders of magnitude here.
DPP-IV
Dipeptidyl peptidase-4, the enzyme that cleaves many peptide hormones at the second residue from the N-terminus. It is the principal reason native GHRH has a half-life of about seven minutes and the reason stabilised analogues carry substitutions at that position.
Albumin binding (DAC)
Covalent attachment of a peptide to serum albumin, which shields it from proteolysis and renal filtration and extends its half-life from minutes to days. The Drug Affinity Complex used in CJC-1295 with DAC works this way. Note that a peptide esterified or acylated simply to prolong action is a different mechanism from conjugation to albumin.
GHRH receptor vs ghrelin (GHS-R1a) receptor
Two distinct receptors on pituitary somatotrophs that both stimulate GH release. GHRH analogues act at the GHRH receptor; GHRP-family peptides act at the ghrelin receptor. Comparing them requires the distinction to be kept straight, because their downstream signalling and side-effect profiles differ.
Secretagogue
A substance that stimulates secretion. In this catalogue it applies to peptides studied for their effect on GH secretion; it says nothing about any clinical use.
Secretory pathway / SNARE complex
The protein machinery that docks vesicles and enables their fusion with the plasma membrane. Peptides that mimic part of the SNAP-25 protein are used in research on this machinery, which is why the Argireline/SNAP-8 pair is described in those terms rather than as a receptor agonist.
Matrikine
A peptide fragment of an extracellular-matrix protein that can signal to cells. The term is descriptive of a mechanism class, not a regulated category or a quality grade.
Quality & compliance
Certificate of Analysis (COA)
A batch-specific analytical record stating what was tested, by which method, against which specification and with which measured result. It is not a regulatory approval. See the verification guide for how to check one.
Safety Data Sheet (SDS)
A structured hazard and handling document, usually in GHS format. Section 14 covers transport classification, and an SDS with that section left blank is a common cause of carrier refusal.
Research Use Only (RUO)
A designation meaning the material is supplied for laboratory investigation and not for human or veterinary use, diagnosis, treatment or cosmetic application. RUO material is not a medicine, is not subject to the quality standards of a medicine, and its documentation is analytical rather than regulatory.
End-use statement
A declaration describing the intended use of a shipment as laboratory research. Routinely requested by customs brokers.
GMP
Good Manufacturing Practice: a manufacturing quality framework for medicinal products. Its scope is pharmaceutical production. A research chemical is not GMP-manufactured by virtue of being made in a controlled facility, so GMP claims should be read against the certificate that supposedly supports them.
Commercial
Kit
This catalogue's selling unit: 10 vials at the stated fill, supplied with a batch COA. All list prices are per kit unless stated otherwise.
List price vs quotation
The published list price is the per-kit figure on the price list. Quotations add the volume discount applicable at your order size and, where relevant, freight and documentation.
Volume discount tiers
Quantity-based discount steps published on the price list: 10% from 5 kits, 20% from 20 kits and 30% from 50 kits. Tier boundaries are stated on the price list itself, not inferred from marketing copy.
OEM / private label
Supply under the buyer's brand, with the buyer's artwork on vials and cartons, always retaining the research-use statement. See the OEM page for the process.
Where to go next
Terms in this glossary are used with their specific meanings across the site: comparison pages for receptor and half-life differences, the COA verification guide for analytical documentation, and the product pages for per-molecule identity data.
FAQ
Where can I find the technical documentation behind these definitions?
The knowledge base at docs.peptidesourcehub.net contains the specification pages, quality-control framework and supplier-qualification guides that sit behind this glossary. This page is the short-form version for procurement readers.
Do these definitions constitute medical or legal information?
No. They describe standard analytical, handling and regulatory terminology as used in research-chemical supply. Nothing here is medical advice, a dosing guide or a legal opinion on import or possession.
Why does the glossary mention what a term does not include?
Because most procurement errors in this category come from a term being used more broadly than it should be — a purity figure without a method, a GMP claim on a research chemical, or a half-life quoted for the wrong analogue. Stating the limits is the point of the entry.