Research Peptide Glossary and Beginner FAQ

5 minute read

This page explains the words used across our catalogue and guides, in plain English, A to Z. Where a term needs more than a sentence, the entry links to the guide that covers it properly — starting with the beginner's guide to research peptides if all of this is new.

Glossary, A–Z

Acetate, or acetate salt

The form most peptides are supplied in. Acetate is a counter-ion — a small charged partner that balances the peptide’s own charge so it can be dried to a solid. It carries weight of its own, so the powder in a vial is never entirely peptide.

Acylation, or lipidation

A fatty chain attached to a peptide. It changes how the molecule dissolves and lets it cling to proteins in the blood, so it lasts much longer. Types, categories and blends explains it.

Agonist

A molecule that fits a receptor and switches it on. A dual agonist switches on two, a triple agonist three. The receptor guide covers the family where this matters most.

Aliquot

A single-use portion split off from a larger amount, so using some never means thawing all of it. The standard defence against freeze-thaw damage.

Amino acid

The building block of peptides and proteins. There are twenty standard ones, and the order they are joined in decides what the molecule is.

Bacteriostatic water

Water with a preservative in it that stops bacteria growing, which is why a vial can be entered more than once. Compared with sterile water in the reconstitution guide.

Batch, or lot

One production run of one compound, made together and tested together, with its own certificate. “Lot” is the same thing under another name; either word can turn up on a label or on a certificate.

CAS number

A registry number identifying a chemical substance, assigned by the Chemical Abstracts Service. It names a substance; it says nothing about what is in a particular vial. One product label can even gather several, as CJC-1295 with DAC and without shows.

Certificate of analysis, or CoA

The laboratory report for one batch: what it is, how pure it is, by what method, on what date. How to read a certificate walks through one.

Chromatogram

The trace an HPLC run produces. Each component of the sample appears as a separate peak, and the size of those peaks is what a purity percentage is worked out from. How to read a certificate sets out where it sits on the document.

Concentration

How strong a solution is — milligrams of peptide in every millilitre of liquid, written mg/mL. It only exists once the powder has been dissolved.

DAC

Short for Drug Affinity Complex: an extra chemical group on the tail of CJC-1295, designed to bond to a protein already circulating in blood so the molecule persists far longer. CJC-1295 with DAC and without compares the two forms.

Diluent

The liquid a dry compound is dissolved in. For peptides, usually bacteriostatic water.

Endotoxin test

A test for bacterial breakdown products in a sample. It is a separate measurement from identity and purity, and a report establishes only the tests it names.

Excipient

Anything freeze-dried alongside the peptide rather than being the peptide — a bulking agent such as mannitol, or a buffer salt. Excipients form part of the cake in the vial and part of its weight.

Freeze-thaw cycle

One round of freezing and thawing. Each one stresses dissolved material, which is why single-use portions are worth the trouble.

HPLC

The test behind the purity percentage. It separates a sample into its parts and reports the target compound as a share of everything detected.

HPLC area percentage

The basis a purity figure is reported on: the target peak’s share of the total peak area on the chromatogram. It compares peaks against peaks rather than weight against weight, which is why it says nothing about salt or moisture in the vial.

In vitro

In glassware and instruments, not in a living thing. It is the setting every research peptide is supplied for.

In vitro research purposes only

The condition every product here is supplied on: a laboratory chemical, never tested or approved for giving to anyone. What that actually means sets out the obligations.

LC-MS

Liquid chromatography joined to mass spectrometry. The sample is separated first and the separated parts are then weighed, so a single run can report purity and identity together rather than needing two.

Lyophilisate, or lyophilised cake

The dry material left in the vial after freeze-drying. It can look like a thin film, a small firm cake, loose powder or a light residue on the glass, and the storage guide explains why none of those appearances means anything is wrong.

Lyophilised

Freeze-dried. Frozen, then held under vacuum so the ice leaves as vapour, giving the dry powder peptides are supplied as. Storing freeze-dried peptides covers what follows.

Mass spectrometry

The test that weighs the molecule, and so confirms it is the right one. The other half of batch testing alongside HPLC.

mg, mcg, mL

A milligram (mg) is a thousandth of a gram, and a microgram (mcg or µg) is a thousandth of a milligram. A millilitre (mL) is a thousandth of a litre. Weight units describe the peptide, volume units describe the liquid.

Modified GRF (1-29)

Another name for CJC-1295 without DAC: a 29-amino-acid chain with four of its positions substituted. It is a different molecule from the DAC form despite sharing a product label, and with DAC and without sets out both.

Molecular weight

How much one molecule weighs. It is fixed by the sequence, so it can be calculated in advance and used to confirm identity.

Nominal content

The amount of peptide a vial is labelled as holding — 10 mg, 20 mg and so on. It is the figure the fill was aimed at. Where a certificate reports a measured mass, that measurement is the finding and the label stays the nominal figure.

Peptide

A short chain of amino acids — usually under about fifty. Longer than that and it is called a protein.

Peptide blend

Two or more peptides freeze-dried into one vial at a fixed ratio. Types, categories and blends covers when that helps and when it does not.

Peptide salt

A peptide paired with a counter-ion so it can be isolated as a dry solid, usually an acetate or a trifluoroacetate. The counter-ion is part of the powder, so the weight of what is in the vial and the amount of peptide in it are two different figures.

Purity

The share of a sample that is the named compound. It describes the peptide-like material the instrument saw, not the weight of the powder — and a high figure does not prove you have the right compound.

Receptor

A docking point on a cell that a signalling molecule fits into, the way a key fits a lock.

Reconstitution

Adding a measured amount of liquid to a freeze-dried peptide to make a solution of known strength. The calculator does the arithmetic.

Retention time

How long a component takes to come off the HPLC column, in minutes. It is characteristic of a molecule under fixed conditions, so a peak arriving at the expected time is consistent with the right compound without proving it.

Sequence

The peptide’s amino acids in their fixed order. Swap one and you have a different peptide.

Sterile water

Clean water with no preservative in it. Suitable for a single use, not for a solution you will come back to.

Sterility

The absence of living micro-organisms in a material, established by a test of its own. It is not the same idea as bacteriostatic: a preservative stops bacteria multiplying in a liquid, which is a different claim about a different material.

TFA, or trifluoroacetate

The other counter-ion peptides are commonly supplied with, left behind by the purification step. Like acetate it is part of the powder’s weight rather than part of the peptide chain.

Traceability

The unbroken chain from a result back to the vial that produced it. Lose the stock code and you lose the chain.

Vial strength

A common way of asking how many milligrams a vial holds. Strictly the label states a quantity rather than a strength, because dry powder has none — strength appears only once liquid is added, and the reconstitution calculator works it out.

Beginner Questions

This vocabulary is the vocabulary Australian Research Peptides uses on its own listings: grade, batch, lyophilised and certificate of analysis carry these meanings across the catalogue, on stock held in Sydney and posted Australia-wide.

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