Reference
Research Peptide Glossary
Plain-English definitions for the terms you'll see on a Certificate of Analysis, in a reconstitution protocol, or in a peptide research paper.
41 of 41 terms
- Amino acid
- The building block of peptides and proteins. Twenty proteinogenic amino acids make up almost all natural sequences.
- Peptide
- A short chain of amino acids joined by peptide bonds, typically fewer than fifty residues.
- Polypeptide
- A longer amino-acid chain (20–50+ residues); the term is structural, not functional.
- Protein
- A polypeptide (or complex of them) that folds into a defined three-dimensional structure.
- Peptide bond
- The covalent amide bond linking the α-carboxyl group of one amino acid to the α-amino group of the next.
- Lyophilized
- Freeze-dried. Removes water under vacuum, producing a dry powder stable for months at −20°C.
- Reconstitution
- Adding a sterile diluent (usually bacteriostatic water) to a lyophilized vial to create a working solution.
- Bacteriostatic water (BAC)
- Sterile water containing 0.9% benzyl alcohol as a preservative; the standard diluent for multi-use research vials.
- Sterile water for injection (SWFI)
- Preservative-free sterile water; used when benzyl alcohol would interfere with an assay.
- HPLC
- High-performance liquid chromatography — the standard method for measuring research-peptide purity by peak area.
- Mass spectrometry (MS)
- Confirms the identity of a peptide by measuring its exact molecular mass and comparing against the theoretical value.
- Certificate of Analysis (COA)
- A third-party tested document listing HPLC purity, MS-confirmed mass, counterion, and residual-solvent limits.
- TFA salt
- Trifluoroacetate counterion, common after reverse-phase HPLC purification. Listed on the COA.
- Acetate salt
- Alternate counterion used when TFA interferes with an assay; often produced by an ion-exchange step.
- Net peptide content
- The percentage of a vial's mass that is the peptide itself, excluding counterion, residual water, and salts.
- Solid-phase peptide synthesis (SPPS)
- The dominant peptide-manufacture method: amino acids are coupled one at a time to a resin-bound growing chain.
- Fmoc / Boc chemistry
- Two protecting-group strategies used in SPPS to control which amine reacts at each coupling step.
- Molecular weight (MW)
- The peptide's mass in daltons. Used to convert between mg, mmol, and µmol.
- IC50
- The concentration of a compound that inhibits a biological process by 50% in an in-vitro assay.
- EC50
- The concentration producing 50% of the maximal effect in an in-vitro assay.
- Receptor
- A protein that binds a ligand (such as a peptide) and initiates a downstream signaling cascade.
- Ligand
- A molecule that binds a receptor. Research peptides are frequently used as receptor ligands.
- Agonist
- A ligand that activates a receptor after binding.
- Antagonist
- A ligand that binds a receptor without activating it, blocking the endogenous agonist.
- GHRP
- Growth-hormone-releasing peptide. A class that acts on the ghrelin receptor (GHS-R1a) to stimulate GH release.
- GHRH analog
- A synthetic analog of growth-hormone-releasing hormone, acting on the GHRH receptor.
- GLP-1
- Glucagon-like peptide 1. An incretin hormone; its receptor is the target of semaglutide and related analogs.
- Incretin
- A gut-derived hormone that potentiates insulin release in response to nutrients (GLP-1, GIP).
- Angiogenesis
- Formation of new blood vessels from existing vasculature — a common outcome measured in tissue-repair peptide research.
- BDNF
- Brain-derived neurotrophic factor; upregulation is a common endpoint in nootropic-peptide neuroscience research.
- Half-life
- The time for a compound's concentration to fall by half. Free peptides usually have short half-lives; analog design often extends it.
- Endotoxin
- Lipopolysaccharide from Gram-negative bacteria. Reported on protein COAs; typically not reported on synthetic-peptide COAs.
- Aliquot
- A single-use sub-portion of a reconstituted stock, frozen to limit freeze–thaw cycles.
- Freeze–thaw cycle
- One round of freezing and thawing a reconstituted peptide; each cycle risks aggregation and purity loss.
- Cold chain
- The temperature-controlled logistics that keep a peptide below its degradation threshold from factory to bench.
- For Research Use Only (RUO)
- A regulatory designation stating a compound is supplied only for laboratory research, not therapeutic use in humans or animals.
- AEDG peptide (Epitalon)
- AEDG is the four-letter code for the tetrapeptide Ala-Glu-Asp-Gly, commonly known as Epitalon. Studied in vitro for telomerase-related pathways and pineal-gland research; supplied strictly For Research Use Only.
- GHK-Cu
- The copper complex of the tripeptide Gly-His-Lys. A widely studied research reagent in skin-biology, angiogenesis, and wound-repair assays. See our GHK-Cu 100mg vial and the buying guide at /research-resources/where-to-buy-ghk-cu.
- CJC-1295 no DAC
- The un-DAC (drug-affinity-complex-free) form of the GHRH analog CJC-1295. Shorter half-life than DAC-modified CJC-1295; commonly paired in research protocols with a GHRP such as GHRP-2 or Ipamorelin.
- GHRP-2
- Growth-hormone-releasing peptide 2. A synthetic ghrelin-receptor agonist used in research alongside GHRH analogs like CJC-1295 no DAC to study pulsatile GH release in vitro.
- Science peptides (research peptides)
- Umbrella term for laboratory-grade peptides synthesized for scientific research — HPLC-purified, mass-spec-identified, sold with a third-party tested COA, and labeled For Research Use Only.
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