LEARNING CENTER
Research Peptide Glossary
Plain-language definitions of the terms used across research-peptide catalogs, testing reports, and handling guides. Every definition describes the laboratory research meaning only.
A
- Acetate salt
- A common salt form in which a synthesized peptide is supplied, pairing acetate counter-ions with the peptide to improve stability and handling. The salt form is noted on documentation because it affects the measured mass of the material.
- Agonist / antagonist
- An agonist is a molecule that binds a receptor and switches on its signaling, while an antagonist binds without activating it and can block other ligands from doing so. The terms describe how a research compound behaves at its molecular target in binding and cell-based assays.
- Aliquot
- A measured portion of a stock solution divided into its own container. Researchers prepare aliquots so a single portion can be used at a time, which limits how often the remaining material is exposed to repeated freeze-thaw cycles.
- Amino acid
- One of the small building-block molecules that link together to form peptides and proteins. The specific order of amino acids in a chain defines a peptide's sequence and its characteristics in the laboratory.
- Amino acid analysis (AAA)
- An analytical method that breaks a peptide down into its individual amino acids and quantifies each one. Laboratories use it to confirm a peptide's composition and to help establish its net peptide content.
- Amylin
- A peptide hormone studied in metabolic research for its role in signaling pathways related to satiety and glucose regulation in preclinical models. On a catalog it refers to the reference research sequence, not a product for human use.
- Angiogenesis
- The biological process by which new blood vessels form from existing ones. It is a frequently studied endpoint in tissue-repair and cell-culture research.
B
- Bacteriostatic water
- Sterile water containing a small amount of benzyl alcohol, an agent that inhibits bacterial growth. In laboratories it is one of the solvents commonly used to reconstitute lyophilized peptide powder for in-vitro work.
C
- CAS number
- A unique numeric identifier assigned to a chemical substance by the Chemical Abstracts Service. It lets researchers reference a specific compound unambiguously across suppliers and databases.
- Cathelicidin
- A family of host-defense peptides studied in laboratory research for their antimicrobial activity and their role in innate-immunity signaling. Catalog entries refer to the research reference sequence.
- Cellular senescence
- A state in which cells permanently stop dividing while remaining metabolically active. It is a common subject of aging and cell-biology research in preclinical models.
- Certificate of Analysis (COA)
- An independent laboratory report that documents, for one specific production lot, a peptide's measured purity and confirmed molecular identity. A lot-matched COA lets a researcher verify the material before use.
- Cold chain
- A temperature-controlled handling and shipping process that keeps a material within a defined cold range from production through delivery. It is relevant to peptides whose stability data indicate they are best kept refrigerated or frozen.
- Counter-ion
- The charged partner supplied with a peptide in its salt form, such as acetate or trifluoroacetate. The counter-ion contributes part of the weighed powder's mass, which is one reason net peptide content is lower than the total amount on the balance.
- C-terminal amide
- A chemical modification at the tail (C-terminus) end of a peptide in which the terminal carboxyl group is converted to an amide. It is noted on documentation because it can affect the peptide's stability and its behavior in assays.
- Cyclic peptide
- A peptide whose ends or side chains are joined to form a ring rather than a straight chain. Cyclization is studied as a way to give a molecule more structural rigidity and greater resistance to enzymatic breakdown in laboratory settings.
D
- Deamidation
- A chemical degradation reaction in which an asparagine or glutamine residue converts into a related acidic residue, slightly shifting a peptide's mass and charge. Analytical testing screens for it because it is a common storage-related impurity.
- Desiccant
- A drying agent such as silica gel, packed alongside a lyophilized peptide to absorb moisture during storage and transit. It helps keep hygroscopic powder dry until the material is reconstituted.
- Disulfide bridge
- A chemical bond linking two cysteine amino acids within or between peptide chains, often stabilizing the molecule's folded shape. Its presence is part of a peptide's structural characterization.
- D-retro-inverso
- A peptide design strategy that reverses the amino acid sequence and substitutes mirror-image (D-form) amino acids. The approach is studied in research as a way to make a peptide more resistant to enzymatic breakdown while preserving its shape.
E
- Endotoxin testing (LAL assay)
- A test for bacterial endotoxin contamination, commonly performed with the Limulus amebocyte lysate (LAL) assay. Endotoxin levels may be reported for research materials because contamination can introduce confounding variables into cell-based experiments.
- ESI-MS (electrospray ionization mass spectrometry)
- A form of mass spectrometry that gently ionizes peptides from solution so their mass can be measured. It is one of the standard methods on analytical reports for confirming that an observed mass matches a peptide's theoretical mass.
- Extracellular matrix
- The network of proteins and other molecules that surrounds cells and provides structural support in tissue. It is a common subject of study in tissue-repair and cell-culture research.
F
- Fmoc chemistry
- A protecting-group strategy used in solid-phase peptide synthesis, named for the fluorenylmethyloxycarbonyl group that temporarily blocks each amino acid's reactive site. It allows a chain to be assembled one residue at a time and is a standard route for producing research peptides.
- Freeze-thaw cycle
- One round of freezing a stored solution and then thawing it for use. Repeated freeze-thaw cycles can degrade a peptide, which is why researchers often divide material into single-use aliquots.
G
- Ghrelin / GHS-R
- Ghrelin is a peptide that binds the growth hormone secretagogue receptor (GHS-R). This ligand-receptor pair is a frequent target in endocrine and metabolic research conducted in preclinical models.
- GHRH receptor
- The cell-surface receptor that binds growth-hormone-releasing hormone (GHRH). It is a target studied in endocrine research examining growth-hormone signaling pathways in laboratory models.
- GIP receptor
- The receptor that binds glucose-dependent insulinotropic polypeptide (GIP), one of the incretin hormones. It is a target in metabolic and endocrine research.
- GLP-1 receptor
- The cell-surface receptor that binds glucagon-like peptide-1 (GLP-1), an incretin hormone. It is a widely studied target in metabolic and endocrine research using preclinical models.
- Glucagon receptor
- The receptor that binds glucagon, a hormone involved in glucose metabolism. It is a research target in studies of metabolic signaling pathways.
- GPCR (G-protein-coupled receptor)
- The large family of cell-surface receptors that many peptide ligands act on to set off intracellular signaling. A number of peptide research targets, including the incretin and melanocortin receptors, belong to this family.
- Growth hormone secretagogue
- A general term for a compound studied for its ability to stimulate the release of growth hormone in laboratory and preclinical models. Many such compounds act at the growth hormone secretagogue receptor (GHS-R).
H
- HPLC (high-performance liquid chromatography)
- An analytical technique that separates the components of a mixture so the proportion of the intended peptide can be measured. HPLC is the standard method for reporting a peptide's purity on a Certificate of Analysis.
- Hygroscopic
- Describing a material that readily draws in moisture from the surrounding air. Many lyophilized peptides are hygroscopic, which is why they are stored with desiccant and allowed to warm to room temperature before opening to limit condensation.
I
- Impurity
- Any material in a peptide sample that is not the intended peptide, such as residual reagents, salts, or byproducts of synthesis. Impurities are quantified during analysis because they can introduce confounding variables into research.
- Incretin
- A class of gut-derived hormones, including GLP-1 and GIP, studied for their role in insulin and glucose signaling. The term describes a research category rather than a single product.
- In-vitro
- Latin for 'in glass'; describes experiments performed outside a living organism, such as in test tubes, cell cultures, or assay plates. Research peptides sold here are intended strictly for in-vitro research use.
- Isoelectric point (pI)
- The pH at which a peptide carries no net electrical charge. It influences the molecule's solubility and its behavior in chromatography and is a calculated property used when developing analytical methods.
K
- Karl Fischer titration
- An analytical titration that measures the residual water content of a dry material. Reporting water content helps a laboratory interpret a lyophilized peptide's mass and confirm the material was thoroughly dried.
- Kisspeptin receptor (KISS1R)
- The receptor, also known as KISS1R or GPR54, that binds kisspeptin peptides. It is a target studied in reproductive and endocrine research examining the pathways that regulate gonadotropin release in preclinical models.
L
- Lipidation
- A modification in which a fatty-acid chain is attached to a peptide, as seen in several long-acting research analogs. The added lipid promotes reversible binding to serum proteins, a mechanism studied for extending a molecule's circulating half-life in preclinical models.
- Lot / batch number
- A code identifying a single production run of a peptide. Because purity can vary between runs, the lot number on a vial must match the one on its Certificate of Analysis.
- Lyophilization
- Freeze-drying: a process that removes water from a peptide under vacuum to leave a stable, dry lyophilized powder. This form is convenient for shipping and storage and is reconstituted before use.
M
- MALDI-TOF mass spectrometry
- Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, a technique that determines peptide mass by timing ionized molecules as they travel to a detector. It is an alternative to electrospray methods for confirming a peptide's identity on analytical reports.
- Mass spectrometry
- An analytical technique that measures the mass of a molecule to confirm its identity. On a Certificate of Analysis, mass spectrometry verifies that the observed mass of a peptide matches its theoretical mass.
- Melanocortin receptor
- A family of cell-surface receptors that bind melanocortin peptides, studied in research on pigmentation and metabolic signaling pathways in preclinical models.
- Mitochondrial-derived peptide
- A short peptide encoded within mitochondrial DNA. Members of this group are studied in cell-biology and aging research for their roles in cellular stress-response pathways.
- Molecular formula
- The notation that lists the number of each type of atom in a molecule, such as carbon, hydrogen, nitrogen, and oxygen. It is part of a peptide's basic chemical identification.
- Molecular weight
- The mass of one molecule of a peptide, usually reported in daltons. It is a core identifying characteristic used to confirm identity by mass spectrometry.
N
- Net peptide content
- The fraction of a supplied powder that is the peptide itself, once bound water, counter-ions, and residual salts are excluded. Because a vial's total weight includes those components, net peptide content reflects how much peptide the material actually contains.
- NNMT
- Nicotinamide N-methyltransferase, an enzyme studied in metabolic and cell-biology research for its role in methylation and energy-related pathways. It appears in the catalog as a research target.
- N-terminal acetylation
- A modification that caps the head (N-terminus) of a peptide with an acetyl group, removing the positive charge that end would otherwise carry. Acetylated sequences are studied because the cap can slow enzymatic degradation approaching from the N-terminal side.
P
- PEGylation
- The attachment of one or more polyethylene glycol (PEG) chains to a peptide. It is studied in research as a way to increase a molecule's effective size and shield it from rapid clearance, which can lengthen how long it persists in circulation in preclinical models.
- Peptide
- A molecule made of amino acids linked by peptide bonds, shorter than a full protein. Research peptides are synthesized for controlled laboratory study and supplied for in-vitro research use only.
- Peptide bond
- The chemical bond that joins one amino acid to the next, forming the backbone of a peptide chain. The number and order of these bonds define the molecule.
- Preclinical
- Describing research carried out in laboratory systems or animal models before any human study. Descriptions of what a peptide is studied for on this site refer to preclinical and in-vitro research.
- Purity
- The percentage of a sample that is the intended peptide rather than impurities. Purity is measured analytically, typically by HPLC, and reported on the Certificate of Analysis; it is the primary quality attribute of a research peptide.
R
- Racemization
- An unwanted side reaction during synthesis in which an amino acid's three-dimensional configuration flips from the natural L-form to the D-form. It is monitored because it produces closely related impurities that can change how a peptide behaves in an assay.
- Reconstitution
- The process of dissolving lyophilized (freeze-dried) peptide powder in a suitable solvent, such as bacteriostatic water, to prepare a solution for laboratory work.
- Reference standard
- A well-characterized material of known identity and purity used as a comparison point in analytical testing. Reference standards help laboratories confirm that a measurement is accurate.
- Research use only
- A designation indicating a product is intended strictly for in-vitro laboratory research and development. It is not a drug, food, or cosmetic, and is not intended for human or veterinary use.
- Retention time
- The time a compound takes to travel through a chromatography column and reach the detector. In HPLC analysis, matching a sample's retention time to that of a reference standard helps confirm the peptide's identity.
- RP-HPLC (reversed-phase high-performance liquid chromatography)
- The most common HPLC mode for peptides, in which molecules separate according to how strongly they interact with a nonpolar column surface. It is the standard technique behind the purity percentage reported on a Certificate of Analysis.
S
- Sequence
- The specific order of amino acids in a peptide, written from one end to the other. The sequence determines the peptide's identity and how it behaves in an experiment.
- Solid-phase peptide synthesis (SPPS)
- The standard method for manufacturing research peptides, in which the chain is built one amino acid at a time on a solid support. The product is then purified and characterized analytically.
- Somatostatin receptor
- A family of cell-surface receptors that bind somatostatin, a peptide that broadly restrains the release of other hormones. These receptors are studied in endocrine and oncology research using preclinical models.
- Storage temperature
- The temperature at which a peptide should be kept to preserve its stability, commonly refrigerated or frozen for longer-term storage. Appropriate storage temperature limits degradation over time.
T
- Telomere
- A protective cap of repeated DNA sequence at the end of a chromosome that shortens as cells divide. Telomeres are a common subject of aging and cell-biology research.
- TFA salt (trifluoroacetate salt)
- A peptide salt form carried over from the purification step of many synthesis routes. Like other salt forms it is recorded on documentation because the trifluoroacetate counter-ion adds mass and can interfere with sensitive assays, so some research applications call for it to be exchanged to an acetate salt.
- Truncated sequence
- An impurity consisting of a peptide chain that is missing one or more amino acids because synthesis did not complete. Truncated sequences are among the impurities measured during purity analysis.
- Tuftsin
- A short peptide fragment studied in immunology research for its reported effects on immune-cell activity in laboratory models. Catalog entries refer to the research reference sequence.
Put the terms into practice
Browse the research library for full guides, or explore the catalog of doctoral chemist tested research peptides.