Peptide Research Glossary
Key terms and definitions used throughout peptide research. From amino acids to VEGF, understand the language of peptide science.
A
Amino Acid
The basic building blocks of peptides and proteins. There are 20 standard amino acids that combine in various sequences to form all peptides and proteins in the body. Each amino acid has a central carbon atom bonded to an amino group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and a unique side chain (R group) that determines its properties.
Angiogenesis
The formation of new blood vessels from pre-existing vessels. This process is critical for wound healing, as new blood vessels deliver oxygen, nutrients, and repair cells to damaged tissue. Peptides like BPC-157 and GHK-Cu promote angiogenesis through VEGF upregulation.
BPC-157 GuideB
Bioavailability
The proportion of a substance that enters the systemic circulation after administration and is available to exert its biological effect. For peptides, bioavailability varies significantly depending on the administration route — subcutaneous injection typically provides better bioavailability than oral administration.
How Peptides WorkBacteriostatic Water
Sterile water containing 0.9% benzyl alcohol as a preservative. Used to reconstitute lyophilised peptide powders for injection. The preservative inhibits bacterial growth, allowing multiple withdrawals from a single vial over a period of up to 28 days.
C
cAMP (Cyclic Adenosine Monophosphate)
A secondary messenger molecule involved in many peptide signalling pathways. When a peptide binds to a G-protein-coupled receptor, it often triggers an increase in intracellular cAMP, which activates downstream enzymes and cellular responses.
Certificate of Analysis (COA)
A document provided by a peptide manufacturer or independent laboratory that verifies the identity, purity, and quality of a peptide product. A proper COA includes HPLC purity data, mass spectrometry results, and a batch number.
Buying Peptides in CanadaCollagen
The most abundant protein in the human body, providing structural support to skin, tendons, bones, and connective tissues. Several peptides, including GHK-Cu and BPC-157, have been shown to stimulate collagen synthesis in research settings.
Compounding Pharmacy
A pharmacy licensed to prepare customised medications according to a physician’s prescription. In Canada, compounding pharmacies can legally prepare certain peptides like Sermorelin, providing pharmaceutical-grade quality under medical supervision.
Peptide Legality in CanadaCytokine
Small signalling proteins released by cells that have specific effects on cell communication and behaviour. Pro-inflammatory cytokines (like TNF-α and IL-6) drive inflammation, while anti-inflammatory cytokines help resolve it. Many research peptides modulate cytokine production.
D
DAC (Drug Affinity Complex)
A chemical modification used in CJC-1295 with DAC that allows the peptide to bind covalently to albumin in the blood. This dramatically extends the half-life from approximately 30 minutes to 6–8 days.
CJC-1295 GuideDPP-4 (Dipeptidyl Peptidase-4)
An enzyme that rapidly degrades certain peptides, including natural GLP-1 and GHRH. Semaglutide was engineered with amino acid substitutions to resist DPP-4 degradation, significantly extending its half-life.
E
Endogenous
Originating from within the body. An endogenous peptide or hormone is one that the body produces naturally, as opposed to exogenous (externally administered) compounds.
Eumelanin
The dark form of melanin pigment responsible for brown and black skin, hair, and eye colour. Eumelanin provides UV protection. Melanotan II stimulates eumelanin production, creating a tan without UV exposure.
Melanotan II GuideExogenous
Originating from outside the body. Exogenous peptides are those administered externally for research or therapeutic purposes, such as synthetic BPC-157 or Ipamorelin.
F
Fibroblast
A type of cell that produces collagen and other components of the extracellular matrix. Fibroblasts are essential for wound healing and tissue repair. Several peptides stimulate fibroblast migration and activity.
G
GH (Growth Hormone)
A peptide hormone produced by the pituitary gland that stimulates growth, cell reproduction, and regeneration. GH levels decline with age. Growth hormone secretagogues like CJC-1295 and Ipamorelin stimulate the body’s own GH production.
GHRH (Growth Hormone-Releasing Hormone)
A 44-amino acid peptide hormone produced by the hypothalamus that stimulates the pituitary gland to produce and release growth hormone. Sermorelin and CJC-1295 are synthetic GHRH analogues.
CJC-1295 vs SermorelinGHRP (Growth Hormone Releasing Peptide)
A class of synthetic peptides that stimulate GH release through the ghrelin/GHS receptor, a different pathway from GHRH. Ipamorelin is a third-generation GHRP known for its high selectivity.
Ipamorelin GuideGLP-1 (Glucagon-Like Peptide-1)
An incretin hormone produced by the gut that stimulates insulin release, suppresses glucagon, slows gastric emptying, and reduces appetite. Semaglutide is a GLP-1 receptor agonist; Retatrutide targets GLP-1 alongside GIP and glucagon receptors.
Semaglutide GuideGPCR (G-Protein-Coupled Receptor)
A large family of cell surface receptors that detect molecules outside the cell and activate internal signal transduction pathways. Most peptide receptors are GPCRs.
GIP (Glucose-Dependent Insulinotropic Polypeptide)
An incretin hormone released from the gut after eating that stimulates glucose-dependent insulin secretion and plays a role in lipid metabolism. Retatrutide is the most potent at the GIP receptor among its three targets.
Semaglutide vs RetatrutideH
Half-Life
The time required for the concentration of a peptide in the blood to decrease by half. Half-life varies enormously between peptides — from minutes (natural GHRH) to over a week (Semaglutide, CJC-1295 with DAC).
How Peptides WorkHealth Canada
The department of the Government of Canada responsible for national public health. Health Canada regulates drugs, natural health products, and medical devices. Peptides for therapeutic use require Health Canada approval.
HPLC (High-Performance Liquid Chromatography)
An analytical technique used to separate, identify, and quantify components in a mixture. In peptide research, HPLC is the standard method for determining peptide purity, typically reported as a percentage (e.g., 98%+ purity).
I
IGF-1 (Insulin-Like Growth Factor 1)
A hormone produced primarily by the liver in response to growth hormone. IGF-1 mediates many of GH’s anabolic effects, including muscle growth, fat metabolism, and tissue repair.
L
Lipolysis
The breakdown of stored fat (triglycerides) into free fatty acids and glycerol, which can then be used as energy. Growth hormone and peptides like AOD-9604 promote lipolysis.
AOD-9604 GuideLyophilisation (Freeze-Drying)
A process used to preserve peptides by freezing them and then removing the water through sublimation under vacuum. Lyophilised peptides are more stable than liquid formulations and have a longer shelf life.
M
Melanocortin Receptor
A family of five G-protein-coupled receptors (MC1R–MC5R) that mediate the effects of melanocortin peptides. MC1R controls pigmentation, MC3R/MC4R influence appetite and sexual function, MC5R affects exocrine glands.
Melanotan II GuideMelanocyte
A cell in the epidermis that produces melanin pigment. Melanocytes contain melanocortin-1 receptors (MC1R), which, when activated by α-MSH or Melanotan II, trigger melanin production.
P
Peptide Bond
The chemical bond formed between two amino acids when the carboxyl group of one reacts with the amino group of another, releasing a molecule of water. Peptide bonds are the links that hold amino acid chains together.
What Are Peptides?Pituitary Gland
A small, pea-sized gland at the base of the brain that produces and releases several important hormones, including growth hormone. The anterior pituitary is the target of GHRH analogues like Sermorelin and CJC-1295.
R
Reconstitution
The process of dissolving a lyophilised (freeze-dried) peptide powder in a liquid solvent, typically bacteriostatic water, to create an injectable solution. Proper reconstitution technique is essential for maintaining peptide integrity.
S
Secretagogue
A substance that stimulates the secretion of another substance. Growth hormone secretagogues (like CJC-1295 and Ipamorelin) stimulate the pituitary gland to secrete growth hormone.
Signal Transduction
The process by which a chemical or physical signal is transmitted through a cell as a series of molecular events. When a peptide binds to its receptor, signal transduction carries the message to the cell’s nucleus or other targets.
Somatostatin
A peptide hormone produced by the hypothalamus that inhibits the release of growth hormone from the pituitary. It acts as the body’s natural brake on GH secretion and is important in understanding how GHRH analogues and GHRPs work.
Somatotroph
The cells in the anterior pituitary gland that produce and store growth hormone. GHRH analogues bind to receptors on somatotroph cells to stimulate GH release.
Subcutaneous Injection
An injection into the layer of fat between the skin and the muscle. This is the most common administration route for research peptides, providing relatively consistent and predictable absorption.
T
Triple Agonist
A compound that simultaneously activates three different receptors. Retatrutide is a triple agonist targeting GIP, GLP-1, and glucagon receptors — addressing appetite suppression, insulin secretion, and energy expenditure in a single molecule.
Retatrutide GuideV
VEGF (Vascular Endothelial Growth Factor)
A signalling protein that promotes the formation of new blood vessels (angiogenesis). Several peptides, including BPC-157, TB-500, and GHK-Cu, upregulate VEGF expression as part of their tissue repair mechanisms.
W
WADA (World Anti-Doping Agency)
The international independent agency that coordinates the fight against doping in sport. WADA maintains the Prohibited List, which includes several peptides banned for use in competitive athletics. Canadian athletes are subject to the WADA code through the CCES.