THE PEPTIDE RESEARCH GLOSSARY

A structural protein found in nearly all cells that gives cells their shape and enables movement. Several peptides used in tissue repair, including TB-500, work by binding to actin and influencing cell migration to damaged tissue.

The primary energy currency of every cell in the body. ATP is produced in the mitochondria through cellular respiration and is the molecule that powers virtually every biological process that requires energy.

The basic building block of all proteins and peptides. There are 20 standard amino acids that occur in human biology. Peptides are chains of amino acids linked together by peptide bonds.

A master metabolic regulator inside cells that responds to low energy availability. When AMPK is activated, the cell shifts toward energy production, fat burning, and metabolic efficiency. Compounds like MOTS-c activate AMPK as part of their mechanism.

The formation of new blood vessels from existing ones. Angiogenesis is essential for tissue repair because new blood vessels bring oxygen, nutrients, and immune cells to damaged areas. BPC-157 is one of the most-studied peptides for promoting angiogenesis.

A type of sterile water containing a small amount of benzyl alcohol that inhibits bacterial growth. In peptide research, BAC water is used for reconstituting lyophilized peptides into solution form, allowing the compound to remain stable for longer than it would in plain sterile water.

The fraction of an administered compound that actually reaches systemic circulation and is available to produce an effect. Peptides typically have very low oral bioavailability because they are broken down in the digestive tract, which is why most are administered by injection.

A selective barrier formed by specialized cells lining the blood vessels of the brain that prevents most substances in the bloodstream from entering brain tissue. A peptide must be small enough or specifically designed to cross the BBB if it is intended to act on the central nervous system. Semax and Selank are examples of peptides that cross the BBB.

A 15-amino-acid peptide originally isolated from a protein found in human gastric juice. BPC stands for Body Protection Compound. It is one of the most extensively studied peptides for tissue repair, angiogenesis, and gastrointestinal protection.

The process by which cells move from one location in the body to another. During tissue repair, cells must migrate to the site of damage to begin healing. TB-500 is one of the most-studied peptides for promoting cellular migration.

The brain and spinal cord, which together coordinate the activity of all parts of the body. Neuropeptides such as Semax, Selank, and PT-141 produce their effects by acting on receptors in the central nervous system.

The graphical output of a chromatography analysis (most commonly HPLC) showing peaks that represent the different compounds in a sample. The size, position, and shape of the peaks indicate the purity of the target compound and the presence of any impurities.

The roughly 24-hour internal cycle that regulates sleep, hormone release, body temperature, and many other biological processes. Several peptides, including Epithalon and DSIP, are studied for their effects on circadian rhythm and sleep architecture.

A synthetic analog of Growth Hormone Releasing Hormone (GHRH) that stimulates the pituitary to release growth hormone. It exists in two main versions — with DAC (Drug Affinity Complex) for extended action and without DAC for shorter, more pulsatile action. Frequently paired with Ipamorelin.

A laboratory document that reports the results of testing performed on a specific batch of a compound. A legitimate COA includes the testing lab, batch number, test date, methods used, and detailed results (purity, identity, and often contamination tests).

A unique identifier that links a specific COA to a specific production batch of a compound. The batch number on the COA must match the batch number on the product itself for the COA to be meaningful for that product.

A non-protein chemical compound that an enzyme requires in order to function. Many enzymes cannot perform their reactions without their cofactor present. Copper, for example, is the cofactor required by the enzyme lysyl oxidase to cross-link collagen, which is why copper-containing peptides like GHK-Cu support tissue formation.

The biological process by which the body produces collagen, the main structural protein in skin, tendons, ligaments, and connective tissue. Several peptides — most notably GHK-Cu — are studied for their ability to stimulate collagen synthesis.

A steroid hormone produced by the adrenal glands that is released in response to stress. Chronically elevated cortisol can disrupt sleep, suppress immune function, and interfere with growth and recovery. One of the reasons Ipamorelin is preferred over older growth hormone secretagogues is that it does not elevate cortisol.

The breakdown of a peptide into inactive fragments, either inside the body (by enzymes) or in storage (by heat, light, moisture, or time). Peptide degradation is the reason most peptides cannot be taken orally and why proper storage matters for maintaining potency.

The deepest stage of non-REM sleep, characterized by delta brainwaves. Delta sleep is when the body performs most physical repair, growth hormone release peaks, and the glymphatic system clears metabolic waste from the brain. DSIP is named for its association with delta sleep.

A nine-amino-acid neuropeptide first identified for its ability to promote delta-wave slow-wave sleep. DSIP is studied for its effects on sleep architecture, stress hormone regulation, and circadian rhythm.

Produced inside the body. Endogenous growth hormone, for example, is the growth hormone the body produces on its own, as opposed to exogenous growth hormone administered from outside.

A toxic substance produced by bacteria. In peptide manufacturing, endotoxin contamination can occur if production conditions are not sterile. Endotoxin testing is a separate quality test from purity testing and should be documented on a thorough COA.

A protein that catalyzes (speeds up) a specific biochemical reaction in the body. Most peptide signaling involves enzymes either as the target of the peptide or as the means by which the peptide is eventually broken down.

A synthetic tetrapeptide originally developed in Russia and studied for its effects on the pineal gland, melatonin production, and telomerase activity. Epithalon is most commonly discussed in the context of sleep, circadian rhythm, and longevity research.

Originating from outside the body. Any compound that is administered rather than produced internally is exogenous. Most peptide research involves administering exogenous peptides to influence endogenous biological systems.

A protein that binds and neutralizes myostatin, the molecule that limits muscle growth. Follistatin is sometimes discussed in the context of peptide research for body composition, though it is not part of this library.

A copper-binding tripeptide naturally found in human plasma. GHK-Cu is one of the most-studied peptides in skin biology and tissue repair, working primarily by stimulating collagen synthesis, activating tissue-remodeling genes, and providing copper as a cofactor for collagen cross-linking enzymes.

A peptide hormone produced primarily in the stomach that signals hunger and stimulates growth hormone release. Some growth hormone secretagogues, including Ipamorelin, work by activating the ghrelin receptor without producing the hunger effects associated with ghrelin itself.

A hypothalamic hormone that signals the pituitary to release growth hormone. Synthetic GHRH analogs such as CJC-1295 are designed to extend or amplify this signaling pathway.

A class of synthetic peptides that stimulate growth hormone release by acting on the ghrelin receptor. Ipamorelin is the most selective and well-tolerated GHRP, producing GH release without significantly affecting cortisol, prolactin, or appetite.

A gut-derived hormone that slows gastric emptying, increases insulin secretion in response to glucose, and reduces appetite by signaling fullness to the brain. GLP-1 receptor agonists like Retatrutide engage this pathway.

A hormone that raises blood glucose by signaling the liver to release stored sugar. Glucagon receptor agonism, when added to GLP-1 agonism, increases energy expenditure and promotes fat breakdown. Retatrutide engages the glucagon receptor as one of its three pathways.

A tripeptide composed of cysteine, glycine, and glutamate that functions as the body's master antioxidant. Glutathione neutralizes free radicals, supports liver detoxification, regenerates other antioxidants, and is involved in many cellular protection pathways.

The brain's waste-clearance system that is most active during deep sleep. The glymphatic system flushes metabolic byproducts — including proteins associated with neurodegenerative disease — from brain tissue. Compounds that deepen sleep architecture support glymphatic function.

A peptide hormone produced by the pituitary gland that promotes tissue growth, repair, and metabolic regulation. GH release naturally pulses throughout the day, with the largest pulse occurring during deep sleep. Many peptides work by amplifying these natural pulses rather than introducing GH directly.

The signaling pathway involving the hypothalamus (GHRH), pituitary (GH), liver (IGF-1), and target tissues. Many peptides in the library — CJC-1295, Ipamorelin, IGF-LR3 — operate at different points along this axis.

The amount of time it takes for the concentration of a compound in the body to fall by half. Peptide half-lives vary widely — from minutes for unmodified peptides to days for modified peptides like CJC-1295 with DAC. Half-life determines how frequently a compound needs to be administered.

Pharmaceutical-grade recombinant human growth hormone — the finished GH molecule itself, identical to the somatropin produced by the pituitary. Unlike GHRH analogs (Sermorelin, Tesamorelin, CJC-1295) or GHRPs (Ipamorelin) that nudge the pituitary to release more of your own GH, HGH delivers growth hormone directly. Studied in research for body composition, recovery, IGF-1 signaling, and metabolic effects. Typically measured in International Units (IU) rather than milligrams.

An analytical chemistry technique that separates the components of a mixture and measures the relative quantity of each. HPLC is the standard method for measuring peptide purity. The output of an HPLC analysis is a chromatogram, where the size of each peak corresponds to the amount of each compound in the sample.

A region of the brain that controls many essential body functions, including hormone release, body temperature, sleep, and appetite. The hypothalamus produces GHRH, which signals the pituitary to release growth hormone.

A peptide hormone produced primarily in the liver in response to growth hormone signaling. IGF-1 mediates many of the tissue-growth effects of GH. IGF-LR3 is a modified version designed to have a longer half-life and stronger anabolic effect.

A modified version of IGF-1 with an extended half-life and reduced binding to IGF-binding proteins, making more of the molecule biologically available. Used in research focused on muscle tissue growth and body composition.

A route of administration in which a substance is injected into muscle tissue. Some research peptides are administered IM rather than subcutaneously, depending on the compound and the desired absorption profile.

The degree to which cells respond to the hormone insulin and take up glucose from the bloodstream. Higher insulin sensitivity is associated with metabolic health. Several peptides, including MOTS-c and Retatrutide, are studied for their effects on insulin sensitivity.

A pentapeptide and selective growth hormone secretagogue that stimulates GH release through the ghrelin receptor without affecting cortisol, prolactin, or appetite. Almost always paired with CJC-1295 in research protocols.

A unit of measurement used for some biological substances based on their biological activity rather than their mass. Insulin and some growth-related compounds are sometimes measured in IU, while most peptides are measured by weight (mg or mcg).

A tripeptide derived from alpha-MSH studied for its anti-inflammatory effects, particularly in gastrointestinal contexts. KPV is one component of the KLOW research blend.

Also called freeze-drying. The process of removing water from a peptide under low pressure and temperature, producing a stable powder that can be stored for long periods without degradation. Most research peptides are sold in lyophilized form to maximize shelf life.

A copper-dependent enzyme that cross-links collagen and elastin fibers, giving connective tissue its strength and structure. Copper-containing peptides like GHK-Cu support lysyl oxidase activity by providing the necessary cofactor.

An analytical technique that measures the mass-to-charge ratio of molecules, providing definitive identification of a compound. In peptide analysis, MS confirms that the molecule being tested is actually the intended peptide, complementing the purity measurement provided by HPLC.

A G-protein-coupled receptor in the central nervous system involved in regulating appetite, sexual function, and energy homeostasis. PT-141 is an MC4 receptor agonist used in research focused on libido and arousal.

A family of receptors and signaling molecules involved in pigmentation, appetite, sexual function, and stress response. PT-141 acts on this system through the MC4 receptor.

The ability of the body to efficiently switch between different fuel sources — primarily carbohydrates and fats — based on availability and demand. Compounds that improve metabolic flexibility (like MOTS-c) support better energy availability and body composition.

A biochemical process in which a methyl group is added to a molecule, regulating gene expression, neurotransmitter synthesis, DNA repair, and many other functions. B-12 (methylcobalamin) is the active form of vitamin B-12 that supports methylation reactions directly.

The active, bioavailable form of vitamin B-12 used directly by the body in methylation reactions. Methylcobalamin does not require enzymatic conversion the way cyanocobalamin does, making it more immediately available.

The energy-producing organelles inside cells, responsible for generating ATP through cellular respiration. Mitochondrial function declines with age and stress, which is why mitochondrial health is a major focus of longevity research.

The process by which cells create new mitochondria, increasing the cell's energy-production capacity. MOTS-c is one of the most-studied compounds for stimulating mitochondrial biogenesis.

A peptide that has been chemically altered to change its properties — most often to resist degradation, extend its half-life, or improve its binding to a target receptor. CJC-1295 with DAC and IGF-LR3 are examples of modified peptides.

A 16-amino-acid peptide encoded within the mitochondrial genome itself. MOTS-c acts as a signaling molecule between the mitochondria and the rest of the body, supporting glucose uptake, mitochondrial biogenesis, and metabolic flexibility.

The insulating sheath that surrounds nerve fibers, allowing fast and efficient transmission of nerve signals. Myelin formation depends on adequate B-12 and other nutrients, which is why B-12 deficiency affects cognition.

A coenzyme found in every cell that is essential for energy metabolism, DNA repair, and the activation of sirtuins. NAD+ levels decline with age, which is associated with reduced cellular energy and accelerated aging biomarkers.

A peptide that acts as a signaling molecule in the nervous system, either as a neurotransmitter or as a modulator of neurotransmitter activity. Semax, Selank, and DSIP are examples of neuropeptides.

A chemical messenger that transmits signals between nerve cells. Dopamine, serotonin, GABA, and acetylcholine are major neurotransmitters. Many neuropeptides influence neurotransmitter levels or receptor activity.

A signaling molecule that regulates vascular tone, blood flow, and inflammation. BPC-157 modulates the nitric oxide system as part of its mechanism for supporting vascular and tissue repair.

A state in which the production of free radicals exceeds the body's ability to neutralize them, leading to cellular damage. Glutathione, NAD+, and other antioxidant systems counter oxidative stress.

A standard of scientific publication in which a research paper is evaluated by independent experts in the field before publication. Peer review is a baseline indicator of research quality but does not by itself guarantee that a study's conclusions are reliable.

A short chain of amino acids — typically two to fifty — linked together by peptide bonds. Longer chains are called proteins. Peptides function as hormones, signaling molecules, and structural components in virtually every biological system.

The chemical bond that links one amino acid to the next in a peptide chain. Peptide bonds are formed during protein synthesis and broken down by proteases when peptides are degraded.

The study of how the body processes a compound — including absorption, distribution, metabolism, and elimination. Pharmacokinetic data describes how much of a compound reaches systemic circulation, how it distributes through tissues, and how long it remains active.

A small endocrine gland in the brain that produces melatonin and regulates circadian rhythm. Epithalon is studied for its effects on pineal gland function and melatonin signaling.

The "master gland" of the endocrine system, located at the base of the brain. The pituitary produces and releases growth hormone, thyroid-stimulating hormone, and many other hormones in response to signals from the hypothalamus.

An enzyme that breaks down proteins and peptides by cleaving peptide bonds. Proteases are abundant in the digestive tract and bloodstream, which is why most peptides have short half-lives and cannot be taken orally.

In research, the detailed plan that describes how a study will be conducted — including dose, frequency, duration, outcome measures, and inclusion criteria. The term is also sometimes used informally to refer to how a compound is administered.

A synthetic melanocortin receptor agonist that acts on the central nervous system through the MC4 receptor. PT-141 is studied for its effects on sexual desire and arousal in both men and women, working through CNS pathways rather than vascular mechanisms.

The percentage of a peptide sample that consists of the intended target compound. Measured by HPLC. High purity (typically 98–99%+) indicates that the synthesis and purification process produced a clean compound. Purity does not measure potency, sterility, or quantity.

A protein, usually located on a cell's surface, that binds to a specific signaling molecule (such as a peptide) and triggers a response inside the cell. Peptides produce their effects by binding to receptors that are tuned to recognize their specific structure.

The process of dissolving a lyophilized peptide in liquid — usually BAC water — to prepare it for use. The concentration of the resulting solution depends on the amount of liquid used and the amount of peptide in the vial.

A synthetic peptide that acts as a triple agonist at the GLP-1, GIP, and glucagon receptors. Retatrutide is currently under investigation in clinical trials for its effects on body composition, metabolic markers, and obesity-related conditions.

A substance that triggers the secretion of another substance. Growth hormone secretagogues are compounds that stimulate the pituitary to release growth hormone. CJC-1295 and Ipamorelin are both GH secretagogues working through different mechanisms.

A synthetic heptapeptide derived from the immune-regulating protein tuftsin. Selank is studied for its anxiolytic effects and modulation of GABAergic and serotonergic systems, often described as producing calm without sedation.

A synthetic heptapeptide derived from a fragment of adrenocorticotropic hormone (ACTH). Semax is studied for its effects on BDNF (brain-derived neurotrophic factor), neuroprotection, and cognitive performance.

A family of proteins that regulate cellular health by influencing gene expression, DNA repair, and metabolism. Sirtuins require NAD+ to function, which is one reason NAD+ is associated with longevity.

The deepest phase of non-REM sleep, characterized by slow brainwaves (delta waves). SWS is associated with physical recovery, growth hormone release, and glymphatic waste clearance in the brain.

The degree to which a peptide retains its structure and activity over time and under various storage conditions. Stability is affected by temperature, light exposure, moisture, and pH. Lyophilized peptides are far more stable than reconstituted peptides.

An injection administered into the layer of fat just beneath the skin. Most research peptides are administered subcutaneously because absorption is reliable and the technique is straightforward. SubQ injection is distinct from intramuscular (IM) injection.

A synthetic peptide based on a 17-amino-acid fragment of thymosin beta-4, a naturally occurring protein involved in cell migration and tissue repair. TB-500 binds to actin and supports the movement of repair cells to damaged tissue.

An enzyme that maintains telomere length — the protective caps on the ends of chromosomes that shorten with each cell division. Telomere length is one biological marker of cellular aging. Epithalon is studied for its effects on telomerase activity.

Laboratory analysis performed by a lab that is independent from the company manufacturing or selling the compound. Third-party testing is the gold standard for COA credibility because the testing lab has no financial incentive to misrepresent results.

The biological process by which the body restores damaged tissue, involving inflammation, cellular migration, angiogenesis, and collagen deposition. Peptides like BPC-157, TB-500, and GHK-Cu each support different stages of this process.

A peptide composed of exactly three amino acids. GHK-Cu (glycyl-histidyl-lysyl copper) and glutathione (glutamate-cysteine-glycine) are both tripeptides.

A compound that activates three different receptors simultaneously. Retatrutide is a triple agonist of GLP-1, GIP, and glucagon receptors, engaging three metabolic pathways at once.

The narrowing of blood vessels, reducing blood flow. The opposite of vasodilation. Some peptides modulate vascular tone as part of their mechanism, though most repair peptides favor vasodilation and angiogenesis.

The widening of blood vessels, increasing blood flow to tissues. Many repair processes depend on adequate vasodilation to deliver oxygen and nutrients to damaged areas.

A research blend combining BPC-157 and TB-500 in a single vial. The combination is used in research focused on accelerated repair across multiple tissue types simultaneously.