Peptide research glossary: key terms for laboratory work

This glossary covers the terms you will meet when working with research peptides. Every entry relates to research use only reagents, and where it helps, we link to the relevant product or quality page.

Terms from A to Z

Agonist

A compound that binds to a receptor and triggers its response. An antagonist does the opposite and blocks the receptor. The term appears in descriptions of many peptides, for example ipamorelin.

Aliquot

A small, precisely measured portion of a larger sample or solution, taken for analysis or further dilution. Splitting a solution into aliquots limits the number of freeze-thaw cycles applied to the whole batch.

Amino acid

An organic molecule containing an amino group and a carboxyl group. Amino acids link through peptide bonds to form peptides and proteins, and their sequence determines the properties of the compound.

Analogue

A compound with a structure similar to a reference molecule, in which one amino acid or chemical group has been changed. Analogues help researchers study how structure relates to activity.

Bacteriostatic water

Water with an added agent that inhibits bacterial growth, used in laboratories to reconstitute lyophilised peptides. You can find it in the shop.

Batch

A defined quantity of product made in a single production run. Each batch carries its own number, so test results can be matched to a specific vial.

CAS number

A unique registry number assigned to chemical substances by the Chemical Abstracts Service. It identifies a substance clearly, regardless of the name a supplier uses.

DMSO

Dimethyl sulfoxide, a polar aprotic solvent used in laboratories to dissolve compounds that are poorly soluble in water. Always check the product data sheet before use, because not every compound dissolves in the same solvent.

ERR

Estrogen-related receptors, a family of nuclear receptors closely related to estrogen receptors. Their role in cellular metabolism is an active area of research.

Freeze-thaw cycle

A repeated freezing and thawing of a solution or lyophilised material. Each cycle can affect the stability of a compound, which is why solutions are often divided into aliquots before freezing.

GHRH

Growth hormone-releasing hormone, a peptide produced in the hypothalamus that stimulates the pituitary gland to release growth hormone. GHRH analogues such as sermorelin are studied in research on the growth hormone axis.

Ghrelin and the GHS-R receptor

Ghrelin is a peptide produced mainly in the stomach, and the GHS-R receptor (growth hormone secretagogue receptor) is its primary receptor. The ghrelin and GHS-R system is widely studied in the context of growth hormone release and metabolism.

HPLC

High-performance liquid chromatography, a method for separating the components of a mixture. For peptides, the HPLC result is reported as the percentage of peak area, which represents the purity of the compound.

In vitro

Studies carried out outside a living organism, in test tubes, cell cultures or biochemical systems. This is the basic stage of laboratory work, where the mechanism of a compound is examined.

In vivo

Studies carried out in a living organism, most often animal models under conditions controlled by the researcher. In vivo findings are usually compared with results from in vitro work.

Lyophilisation

Freeze-drying by sublimation at low temperature under vacuum. It preserves the structure of a peptide as a dry powder (lyophilisate), which makes storage and transport easier.

Melanocortins

A family of peptides derived from proopiomelanocortin (POMC) that act on melanocortin receptors. They are studied in relation to pigmentation and central nervous system functions, for example in the case of PT-141.

Mitochondrion

A cellular organelle responsible for energy conversion. Mitochondrial peptides such as MOTS-c are studied for their influence on cellular metabolism.

Molar mass

The mass of one mole of a substance, expressed in g/mol and calculated from the molecular formula. It is needed to convert mass into concentration, for example in our concentration calculator.

Molecular formula

A notation that gives the number of atoms of each element in a molecule. Together with the molar mass, it helps confirm the identity of a compound.

MS (mass spectrometry)

An analytical method that measures the mass of molecules. It confirms the identity of a compound by comparing the measured mass with the mass expected for its sequence. Our quality page explains how MS results are reported.

NAD+

Nicotinamide adenine dinucleotide, a coenzyme present in all living cells. It takes part in redox reactions and energy metabolism, which is why it is widely studied in cell biology. See NAD+.

Peptide

A compound built from a short chain of amino acids joined by peptide bonds. Peptides are generally considered to have up to several dozen amino acid residues.

Peptide impurities

Peptides with an incorrect sequence, shortened or modified forms that can arise during synthesis. HPLC and MS detect them, and their share determines the purity of a batch.

Polypeptide

A longer chain of amino acids that forms the building block of proteins. The boundary between a peptide and a polypeptide is not strict and depends on the convention used.

Preclinical model

A research model, cellular or animal, used before clinical studies to evaluate mechanisms of action and safety profiles. It allows experiments to be planned under controlled conditions.

Reconstitution

Preparing a solution from a lyophilisate by adding a suitable solvent, usually bacteriostatic water, under clean and sterile conditions. The product data sheet describes the volume and the procedure.

Secretagogue

A compound that stimulates the release of a hormone, such as growth hormone, by acting on secretory cells. Ipamorelin is an example of a secretagogue described in the scientific literature.

Sequence

The order of amino acids in a peptide, usually written from the amino (N) end to the carboxyl (C) end using one-letter or three-letter codes. The sequence is the basis for identifying a compound.

Stability

The ability of a compound to keep its composition and purity over time under defined storage conditions. It depends on the form (lyophilisate or solution), temperature and the number of freeze-thaw cycles.

Sterility

The absence of living microorganisms. In practice it is achieved through sterile preparation in clean conditions, and storage follows the instructions on the product data sheet.

Telomerase

An enzyme that rebuilds the ends of chromosomes, known as telomeres. Telomerase research relates to cellular ageing, see the cellular ageing category.

Trifluoroacetate salt (TFA)

A salt of trifluoroacetic acid that remains in a peptide preparation after purification by HPLC. It affects the mass and properties of the sample, which is why it is taken into account in the product description.