Glossary
Key terms.
53 entries across 5 categories. Each entry links to a related article where one exists. Alphabetical within each category.
Compounds
- Amylin
- A 37-amino-acid peptide co-secreted with insulin from pancreatic beta cells. Modulates gastric emptying, glucagon suppression, and central satiety.
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- BPC-157
- Body Protection Compound. A 15-amino-acid synthetic peptide derived from a sequence in gastric juice. One of the most-studied tissue-research peptides.
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- Cagrilintide
- A long-acting amylin analog engineered for once-weekly administration. Studied in combination with incretin agonists in metabolic research.
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- CJC-1295
- A long-acting GHRH analog with an albumin-binding modification. Developed at ConjuChem in Montreal (Teichman et al. 2006).
- GHK-Cu
- Glycyl-L-histidyl-L-lysine bound to copper(II). A tripeptide-metal complex studied in tissue-research and cosmetic literature.
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- GIP
- Glucose-dependent Insulinotropic Polypeptide. An incretin hormone released from the gut that triggers insulin secretion. The "G" in dual-agonists like tirzepatide.
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- GLP-1
- Glucagon-Like Peptide-1. The most-studied incretin hormone. Native ligand for GLP-1R.
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- Hexarelin
- A hexapeptide GHRP developed in Italy in the early 1990s. Less selective than ipamorelin — raises cortisol and prolactin alongside GH.
- Insulin
- The original peptide drug. Isolated in Toronto 1921 (Banting & Best); sequenced in Cambridge 1958 (Sanger); first total synthesis Shanghai 1965.
- Ipamorelin
- A selective pentapeptide ghrelin-receptor agonist. Triggers pulsatile GH release without affecting cortisol or prolactin.
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- Oxytocin
- The first peptide hormone ever chemically synthesized in the laboratory. Vincent du Vigneaud, Cornell 1953. Nobel Prize 1955.
- Retatrutide
- A GLP-1 / GIP / glucagon triple agonist in clinical research. The next-generation analog of tirzepatide.
- Semaglutide
- A long-acting GLP-1 receptor agonist. The single-receptor counterpart to tirzepatide.
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- Somatostatin
- A 14-residue cyclic peptide that inhibits both growth-hormone and insulin secretion. Discovered by Guillemin at the Salk Institute, 1973.
- TB-500
- A 17-amino-acid fragment of Thymosin Beta-4. Studied in tissue-repair research, frequently paired with BPC-157.
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- Tirzepatide
- The first approved dual GLP-1 / GIP receptor agonist. A 39-amino-acid peptide engineered for once-weekly administration.
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Receptors
- AMY1-R
- Calcitonin-receptor / RAMP1 heterodimer. The principal amylin receptor.
- GHSR-1a
- Growth-Hormone Secretagogue Receptor 1a. The ghrelin receptor. The binding site for ipamorelin and other GHRPs.
- GIPR
- The GIP receptor. A class-B GPCR on pancreatic beta cells. One of two receptors tirzepatide engages.
- GLP-1R
- The GLP-1 receptor. The most-studied incretin GPCR. Target of semaglutide, liraglutide, and the GLP-1 side of tirzepatide.
- GPCR
- G-Protein-Coupled Receptor. The seven-transmembrane receptor superfamily. Most peptide-hormone receptors are class-B GPCRs.
Techniques
- Bacteriostatic water
- Sterile water containing 0.9% benzyl alcohol as preservative. The standard reconstitution solvent for research peptides; provides a ~28-day refrigerated storage window.
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- ESI-MS
- Electrospray-Ionization Mass Spectrometry. A standard mass-spec method for peptide identity confirmation. Reads multiply-charged ions in the m/z 500–2000 range.
- Fmoc
- 9-fluorenylmethoxycarbonyl. A protecting group used in solid-phase peptide synthesis. The modern default chemistry.
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- HPLC
- High-Performance Liquid Chromatography. The standard analytical method for research peptide purity. Reverse-phase with C18 column and UV detection at 220 nm is the default.
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- LAL assay
- Limulus Amebocyte Lysate. Classical endotoxin assay using horseshoe-crab blood. Reports EU/mg.
- Lyophilization
- Freeze-drying. The default preservation method for research peptides. Produces a stable solid that can be reconstituted with appropriate solvent.
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- MALDI-TOF
- Matrix-Assisted Laser Desorption / Ionization Time-Of-Flight. A mass-spec method common in peptide labs. Reads predominantly singly-charged ions.
- Mass spectrometry
- Analytical technique that measures molecular mass. Used in peptide COAs to confirm identity. Standard methods: MALDI-TOF, ESI-MS.
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- rFC assay
- Recombinant Factor C assay. The modern endotoxin alternative to LAL — recombinant, no horseshoe-crab dependency.
- SPPS
- Solid-Phase Peptide Synthesis. The Merrifield (1963) chemistry that anchors peptide synthesis to a resin bead, enabling routine peptide manufacturing.
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Concepts
- AUC
- Area Under the Curve. The integrated drug exposure over time. The primary pharmacokinetic readout for peptide therapeutics.
- Counter-ion
- The non-peptide ion accompanying the peptide in solid form. Typically TFA (trifluoroacetate) or acetate. Affects solubility and assay compatibility.
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- Endotoxin
- Lipopolysaccharide from Gram-negative bacterial cell walls. Activates TLR4; can confound inflammation assays. Measured in EU/mg via LAL or rFC assay.
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- Half-life
- The time for serum drug concentration to drop by half. For peptide therapeutics, ranges from minutes (ipamorelin ~2 h) to days (semaglutide ~168 h).
- Hydrolysis
- Cleavage of a peptide bond by water. The dominant degradation pathway for peptides in aqueous solution. Slowed by lyophilization and refrigeration.
- Incretin
- A class of gut-derived hormones that potentiate insulin release in response to a meal. GLP-1 and GIP are the canonical examples.
- Net peptide mass
- The mass of pure peptide in a vial, distinct from gross vial mass. Gross = peptide + counter-ion + water. Critical for concentration-sensitive research.
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- Peptide bond
- The covalent amide bond linking adjacent amino acids in a peptide chain. The C–N bond formed by condensing a carboxyl and an amine.
- Peptide content
- The percentage of the gross vial mass that is actual peptide. Typically 70-90% — the rest is counter-ions and water.
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- Pulsatile GH release
- The endogenous pattern of growth-hormone secretion: large pulses followed by trough periods. Functionally distinct from continuous exogenous GH.
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- Purity (HPLC area %)
- Peptide purity measured as the integrated area of the target peak divided by total integrated peak area in an HPLC chromatogram.
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- Receptor selectivity
- The relative affinity of a ligand for its intended receptor versus other receptors. Ipamorelin is the canonical example of a clean GHRP selectivity profile.
Regulatory & documentation
- Bioburden
- Total microbial contamination in a sample. Reported in colony-forming units per gram (CFU/g). Reference threshold: <100 CFU/g.
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- CDMO
- Contract Development and Manufacturing Organization. The companies that synthesize peptide API at scale for the global research market.
- Certificate of Analysis (COA)
- The supplier's per-lot documentation of identity, purity, and content. Should include HPLC chromatogram, mass spec, counter-ion identity, and peptide content.
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- EMA
- European Medicines Agency. The European regulatory authority for medicinal products.
- FDA
- United States Food and Drug Administration. The US regulatory authority for pharmaceuticals.
- GMP
- Good Manufacturing Practice. The quality-assurance regulatory framework that governs pharmaceutical manufacturing.
- Lot number
- The unique identifier for a specific manufacturing batch. Should appear on both the vial and the matching Certificate of Analysis.
- Lyophilized
- Freeze-dried. The default storage form for research peptides. Stable at -20°C for years if kept dry.
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- Research Use Only
- A regulatory designation indicating the compound is intended for laboratory and educational research, not human consumption.
- TFA
- Trifluoroacetate. The standard counter-ion produced by preparative HPLC peptide purification.
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