What is a research peptide?

The term is printed on every vial, yet it is rarely explained. This article sets out what a peptide is, what labelling for research use means and how to tell documented material from material that comes without paperwork.

A peptide is a short chain of amino acids

Amino acids are the building blocks of proteins. Join a few of them together and you have a peptide; join many and you have a protein. There is no fixed boundary, but the usual cut-off is around fifty amino acids. BPC-157 consists of fifteen, GHK-Cu of three and Semax of seven.

The order of the amino acids is called the sequence, and it defines the molecule completely. Two preparations with the same sequence are the same substance, whoever made them. What differs is how cleanly the synthesis ran and what else is in the vial.

"For research use only" states a purpose, not a quality grade

The label sets out what the material is intended for: experiments outside a living organism, in other words in vitro. It does not suggest inferior material, nor particularly good material. It says that the substance is not placed on the market as a medicine, a food or a cosmetic, and that it is not intended for human consumption.

That purpose also determines what a reputable supplier leaves unsaid. Information on human use, whether quantities, expected changes in the body or personal reports, has no place alongside a research chemical. A seller who provides it anyway is selling something other than what the label says. The research use page sets out how UKPeps applies this.

How to recognise documented material

Four details can be checked without owning a laboratory:

CAS number: a globally unique identifier for a chemical substance. If it is given, any database will tell you which substance is meant. If it is missing for a single substance, the simplest form of unambiguous identification is missing too.
Lot number: it links the vial in your hand to one specific production run. Without it, no test report can be matched to the vial.
Certificate of analysis: a laboratory's report on exactly that lot, with method, measured value and date. A certificate without a lot number proves nothing.
Specification: the value a supplier guarantees, for example at least 98%; UKPeps states none. It is not the same as the measured value and should be kept clearly apart from it.

UKPeps publishes its certificates of analysis openly, with no account and no request needed. They are in the certificate library, each with lot number, date of analysis, testing laboratory and, where the report states one, measured purity.

Lyophilised means freeze-dried

Peptides arrive in the vial as a loose white powder. The substance was frozen in solution and the water was removed under vacuum without ever turning liquid. The result is dry and therefore keeps far longer than a ready-made solution. Before use in the laboratory, solvent is added again; this step is called reconstitution. How to keep the dry material in good condition is covered in storing lyophilised peptides.

Purity is a number with a method

A purity figure without a method is worthless. The usual method is high-performance liquid chromatography, or HPLC: the sample is passed through a separation column, its components arrive at different times, and the target peptide's share of the total peak area gives the percentage. In addition, mass spectrometry checks whether the mass matches the expected sequence. Both appear on the certificates, and how the two methods work together has its own article.

Questions

Is a research peptide the same as a medicine?

No. A medicine goes through an authorisation process and is intended to be used. A research chemical is intended for experiments outside a living organism and is expressly not for human consumption.

Why do research blends have no CAS number?

A CAS number designates a single substance. When a vial contains several peptides, there is no shared number for the mixture; the composition is given in the product name instead.

Why does UKPeps not state a minimum purity?

A minimum purity is a guaranteed specification, the value every lot has to reach. What was actually measured is on the certificate of analysis for each lot and is often higher.