Peptide Glossary: 120+ Research Terms Defined

A working glossary of the 96 most-used terms in research peptides — compounds, classes, testing methods, regulatory framework, and pharmacology concepts. Each term gets a one-paragraph plain-language definition. Where a term refers to a compound LiveWell carries, the definition links directly to the product page so you can see the COA and order from the same place you confirmed the definition.

Compounds A-Z

5-Amino-1MQ

A small-molecule inhibitor of nicotinamide N-methyltransferase (NNMT). Not technically a peptide; studied for its effects on adipocyte metabolism and longevity-pathway signaling. View product →

AOD-9604

A 16-amino-acid synthetic fragment of human growth hormone (residues 176-191). Retains lipolytic activity without growth-promoting or insulin-like effects. View product →

BPC-157

Body Protection Compound — a 15-amino-acid synthetic peptide derived from a protein found in human gastric juice. Most-studied for tissue repair, gastrointestinal protection, and tendon-to-bone healing. View product →

CJC-1295 No DAC

A 30-amino-acid modified GHRH analog without the Drug Affinity Complex modification. Half-life ~30 minutes — closer to natural GHRH pulsatility than the With-DAC variant. View product →

CJC-1295 With DAC

CJC-1295 with the Drug Affinity Complex modification, which binds the molecule to albumin and extends half-life to ~8 days. Studied for sustained GH-axis stimulation.

DSIP

Delta Sleep-Inducing Peptide — a 9-amino-acid neuropeptide isolated from rabbit cerebral venous blood in 1977. Studied for slow-wave sleep modulation and stress response.

Elamipretide

A small mitochondria-targeted tetrapeptide (also called SS-31). Studied for cardiolipin stabilization and mitochondrial dysfunction in age-related disease models.

Epitalon

A synthetic 4-amino-acid peptide (Ala-Glu-Asp-Gly) developed at the St Petersburg Institute of Bioregulation and Gerontology. Studied for telomerase induction and longevity.

FOXO4-DRI

A 26-amino-acid D-retro-inverso peptide that disrupts the FOXO4-p53 interaction. Studied as a senolytic — selectively eliminating senescent cells in aging models.

GHK-Cu

A copper-binding tripeptide (Gly-His-Lys + Cu²⁺) that occurs naturally in human plasma. Studied for skin remodeling, wound healing, and antioxidant signaling. View product →

Glutathione

A tripeptide (γ-Glu-Cys-Gly) that serves as the body’s master intracellular antioxidant. Central to detoxification pathways and redox homeostasis. View product →

Hexarelin

A synthetic hexapeptide GHRP studied for growth hormone release and cardiac tissue protection. Less selective than Ipamorelin (raises cortisol/prolactin).

Humanin

A 24-amino-acid mitochondrially-derived peptide (MDP) studied for cytoprotection, neuroprotection in Alzheimer’s models, and metabolic regulation.

IGF-1 LR3

Insulin-like Growth Factor-1 Long Arg3 — an 83-amino-acid IGF-1 analog with reduced binding to IGFBP proteins. Half-life ~20-30 hours vs ~10 minutes for native IGF-1. View product →

Ipamorelin

A selective 5-amino-acid pentapeptide GHRP that stimulates growth hormone release without significantly affecting cortisol or prolactin. The most-selective GHRP in research use. View product →

Klotho

A 1,012-amino-acid transmembrane protein originally identified as an aging-suppressor gene. The cleaved soluble form circulates as a hormone studied for longevity signaling.

KLOW Blend

A four-component research peptide blend combining BPC-157, GHK-Cu, TB-500, and KPV. Studied for overlapping anti-inflammatory and tissue-repair pathways. View product →

KPV

A C-terminal tripeptide of α-MSH (Lys-Pro-Val). Studied for anti-inflammatory effects in the gastrointestinal tract and skin.

LL-37

A 37-amino-acid antimicrobial peptide derived from human cathelicidin. Studied for broad-spectrum antimicrobial activity and immune modulation.

MOTS-c

A 16-amino-acid mitochondrially-derived peptide encoded within the mitochondrial 12S rRNA gene. Studied for metabolic regulation and exercise mimicry. View product →

NAD+

Nicotinamide adenine dinucleotide — a coenzyme present in every cell, central to energy metabolism, DNA repair, and sirtuin signaling. Not technically a peptide; declines significantly with age. View product →

Oxytocin

A 9-amino-acid neuropeptide produced in the hypothalamus. Studied for social bonding, lactation, and parturition signaling.

PT-141 (Bremelanotide)

A 7-amino-acid synthetic melanocortin receptor agonist — same compound as the FDA-approved Vyleesi. Acts on the central nervous system rather than peripherally. View product →

Retatrutide

A 39-amino-acid triple agonist of the GLP-1, GIP, and glucagon receptors. Currently in late-stage clinical trials (TRIUMPH series); shows the largest body-weight reductions of any GLP-1-class compound studied to date. View product →

Selank

A synthetic 7-amino-acid analog of tuftsin developed in Russia. Studied as an anxiolytic nootropic with proposed GABAergic and BDNF mechanisms. View product →

Semaglutide

A 31-amino-acid GLP-1 receptor agonist — the active compound in Ozempic, Wegovy, and Rybelsus. Half-life ~7 days due to C-18 fatty acid acylation. View product →

Semax

A synthetic 7-amino-acid peptide based on the ACTH(4-7) fragment with a Pro-Gly-Pro extension. Studied as a nootropic; used clinically in Russia for ischemic stroke recovery. View product →

Sermorelin

A 29-amino-acid synthetic fragment of GHRH that stimulates pituitary GH release. Half-life ~10-20 minutes — preserves natural pulsatility. View product →

TB-500

A synthetic 17-amino-acid fragment of Thymosin Beta-4 (TB4). Studied for cell migration, wound healing, and tissue repair. View product →

Tesamorelin

A 44-amino-acid stabilized GHRH analog — the only GHRH analog with FDA approval (as Egrifta). Studied primarily for visceral adipose tissue metabolism. View product →

Thymosin Alpha-1

A 28-amino-acid peptide hormone produced by the thymus gland. Studied for immune modulation, particularly in chronic viral infections and cancer immunology.

Thymosin Beta-4 (TB4)

A 43-amino-acid peptide present in nearly every human cell. The active fragment is sold as TB-500 for research use.

Tirzepatide

A 39-amino-acid dual agonist of the GLP-1 and GIP receptors. The active compound in Mounjaro and Zepbound. Half-life ~5 days. View product →

Tuftsin

A naturally-occurring 4-amino-acid immunomodulator (Thr-Lys-Pro-Arg). Selank is its synthetic analog.

Vasopressin

A 9-amino-acid neuropeptide hormone (also called antidiuretic hormone). Studied for water retention, blood pressure regulation, and social cognition.

Wolverine Stack

A community-coined name for the BPC-157 + TB-500 paired research bundle. The most-cited two-peptide combination in connective-tissue repair literature. View product →

Compound Classes & Categories

Antimicrobial Peptide (AMP)

A class of peptides that exert direct antimicrobial activity. LL-37, KPV, and the cecropins are prominent examples.

Cyclic Peptide

A peptide with at least one cyclic portion (head-to-tail or side-chain-to-backbone). Cyclization typically increases stability and bioavailability.

GHRH Analog

Growth hormone-releasing hormone analog. A class of peptides that stimulate the pituitary to release GH via the GHRH receptor. Includes Sermorelin, CJC-1295, Tesamorelin.

GHRP

Growth hormone-releasing peptide. A class of compounds that stimulate GH release via the ghrelin/GHS-R1a receptor — distinct from GHRH receptor signaling. Includes Ipamorelin, GHRP-2, GHRP-6, Hexarelin.

GHS (Growth Hormone Secretagogue)

Umbrella term for compounds that stimulate GH secretion, including both GHRH analogs and GHRPs.

GLP-1 Receptor Agonist

A class of compounds that bind and activate the glucagon-like peptide-1 receptor. Includes Semaglutide, Liraglutide, Dulaglutide, and component agonism in Tirzepatide and Retatrutide.

Lyophilized

Freeze-dried. The standard form for shipped research peptides — increases shelf stability vs liquid solution. Reconstituted with bacteriostatic water before use.

Melanocortin Receptor Agonist

A class of compounds that activate one or more of the five melanocortin receptors (MC1R-MC5R). PT-141 (Bremelanotide) is a research-relevant MC4R-focused agonist.

Mitochondrially-Derived Peptide (MDP)

A class of peptides encoded within the mitochondrial genome rather than the nuclear genome. Includes Humanin, MOTS-c, and the SHLP family.

Nootropic Peptide

A peptide studied primarily for cognitive enhancement effects — focus, memory, learning, neuroprotection. Includes Selank, Semax, and Cerebrolysin.

Senolytic

A compound that selectively eliminates senescent cells. FOXO4-DRI is the most-studied peptide senolytic; small-molecule senolytics include Dasatinib + Quercetin.

Triple Agonist

A compound that simultaneously activates three different receptors. Retatrutide is the lead triple agonist in clinical development (GLP-1 + GIP + glucagon).

Testing & Quality

Bacteriostatic Water

Water that contains 0.9% benzyl alcohol as a preservative — prevents bacterial growth in multi-use research vials. Standard solvent for peptide reconstitution.

Batch-Specific COA

A COA whose lot number matches the lot number on your physical vial. Distinct from a ‘representative’ COA that shows numbers from a different batch. The batch-specific COA is the only verifiable proof of what’s in your vial.

COA

Certificate of Analysis. The document that accompanies a research-peptide vial showing batch-specific purity, identity, water content, and endotoxin numbers from a third-party lab.

Endotoxin

Lipopolysaccharide fragments from bacterial cell walls. Common contaminant in peptides manufactured without strict process controls. Industry-acceptable: <1.0 EU/mg; high-quality: <0.5 EU/mg.

HPLC

High-Performance Liquid Chromatography. The standard analytical method for measuring peptide purity. The HPLC chromatogram shows the peptide’s main peak with any impurity peaks resolved separately.

Identity Testing

Confirmation that a vial contains the labeled peptide and not a similar analog or a different compound. Mass spectrometry is the standard identity test.

LAL Assay

Limulus Amebocyte Lysate assay — the standard test for endotoxin contamination in peptide samples. Result expressed in EU/mg (endotoxin units per milligram).

Mass Spectrometry (MS)

An analytical technique that measures the mass-to-charge ratio of ions to confirm a peptide’s molecular weight and identity. Always paired with HPLC on a credible COA.

Purity Threshold

The minimum acceptable HPLC purity percentage. Industry floor: 95%. Credible vendors: ≥98%. LiveWell standard: ≥99%.

Reconstitution

The process of dissolving a lyophilized (powdered) peptide in bacteriostatic water for use in research. The volume of water determines the final concentration.

Stability Testing

Long-term study of how a peptide’s purity, potency, and physical characteristics change over time under defined storage conditions.

Third-Party Lab

An independent contract testing facility — not the vendor’s in-house lab. The presence of a named third-party lab on the COA is a key trust signal.

Water Content (Karl Fischer)

Residual moisture in a lyophilized peptide. Measured by Karl Fischer titration; reported as a percentage on the COA. Lower water content correlates with longer shelf stability.

Industry & Regulatory

503A Compounding Pharmacy

A pharmacy that compounds drug products for individual patient prescriptions under USP standards. Distinct from research-peptide vendors.

503B Outsourcing Facility

A facility registered with FDA to manufacture compounded drug products in batches without patient-specific prescriptions.

Affiliate Program

A revenue-share model where partners earn commission on referred sales. LiveWell’s affiliate program: 25% commission, 90-day cookie, recurring on subscriptions.

API

Active Pharmaceutical Ingredient — the raw peptide material used in formulation. Different from API in technology contexts (Application Programming Interface).

cGMP

Current Good Manufacturing Practice. The FDA’s quality system regulation for pharmaceutical manufacturing. Research peptide vendors are not required to operate under cGMP.

Compounded Drug

A drug prepared by a pharmacist or physician for an individual patient. Compounded GLP-1s have been a major industry topic in 2024-2026.

DTC

Direct-to-Consumer. The e-commerce sales model for selling research peptides directly to end-users (researchers) rather than through B2B intermediaries.

FDA

U.S. Food and Drug Administration. Research peptides are not FDA-approved for therapeutic use; they are sold for laboratory and research use only.

FDA-Approved

A status indicating a compound has completed clinical trials and received FDA marketing authorization. Examples in the GLP-1 space: Ozempic (Semaglutide), Mounjaro (Tirzepatide).

IND

Investigational New Drug application — the FDA submission required to begin clinical trials with an unapproved compound.

MOQ

Minimum Order Quantity. Common in B2B / wholesale and private-label peptide ordering.

Private Label

A business model where a manufacturer (e.g., LiveWell) produces peptide products under another company’s brand name and packaging.

Research Use Only (RUO)

A regulatory designation indicating a product is not intended for human consumption, injection, or administration. Required labeling for legitimate research peptide vendors.

USP

United States Pharmacopeia. Sets quality standards for medicines and dietary supplements in the United States.

Wholesale

B2B sales of peptides at volume discounts to clinics, compounding pharmacies, and resellers.

Pharmacology & Concepts

Acylation

The addition of a fatty acid chain to a peptide. Used to extend half-life — Semaglutide’s C-18 acylation enables once-weekly dosing.

Adipocyte

A fat cell. Many metabolic peptides (AOD-9604, 5-Amino-1MQ, GLP-1 family) are studied for their effects on adipocyte function.

Amino Acid

The building block of peptides and proteins. Twenty standard amino acids are used by the human genetic code.

BDNF

Brain-derived neurotrophic factor. A protein that promotes neuron survival and growth. Modulated by Selank and Semax in research.

Bioavailability

The proportion of an administered dose that reaches systemic circulation in active form. Most peptides have low oral bioavailability — hence injection or intranasal as common research routes.

E-E-A-T

Experience, Expertise, Authoritativeness, Trustworthiness. Google’s quality framework, especially relevant for health and research content.

Half-Life

The time required for a compound’s concentration in the blood to decrease by 50%. Determines dosing frequency and duration of action.

IGFBP

Insulin-like growth factor binding protein. Carrier proteins that bind IGF-1 in plasma. The IGF-1 LR3 modification reduces IGFBP binding to extend half-life.

Lipolysis

The breakdown of stored fat. AOD-9604 is studied as a lipolytic without affecting blood glucose.

Mitochondrial Biogenesis

The formation of new mitochondria within a cell. Studied for MOTS-c, NAD+, and exercise-mimetic effects.

Peptide Bond

The covalent bond between the carboxyl group of one amino acid and the amino group of the next. The backbone of all peptides and proteins.

Pulsatile Release

GH and other hormones are normally released in pulses rather than continuously. Pulsatile patterns are studied because they often produce different downstream effects than steady-state exposure.

Receptor Agonist

A compound that binds and activates a receptor, mimicking the effect of the natural ligand.

Receptor Antagonist

A compound that binds a receptor without activating it — blocks the natural ligand from binding.

Selectivity

The degree to which a compound activates only its intended receptor without affecting others. Ipamorelin’s selectivity for the ghrelin receptor (vs cortisol/prolactin axes) is what made it the GHRP of choice.

Sequence

The specific order of amino acids in a peptide. Two peptides with the same length but different sequences are entirely different molecules.

Sirtuin

A family of NAD+-dependent enzymes (SIRT1-SIRT7) involved in metabolic regulation, DNA repair, and longevity signaling.

Stack

Community term for two or more compounds used together in a research protocol — e.g., Wolverine Stack (BPC-157 + TB-500), GHRH+GHRP stacks.

VEGFR2

Vascular endothelial growth factor receptor 2. Upregulated by BPC-157 — proposed mechanism for its angiogenic effects.

γ-Glutamyl Bond

An unusual peptide bond using the gamma-carboxyl of glutamic acid. Found in glutathione; resists most peptidases.

For laboratory and research use only. All references to LiveWell Peptides products are for research use; not intended for human consumption, injection, topical application, or any other administration to the human body. This glossary is informational and not medical advice.