Peptide Research Glossary
A comprehensive reference of 60+ terms used in peptide research, synthesis, analysis, and laboratory practice. Updated March 2026.
A
Amino Acid
Organic molecules that serve as the building blocks of peptides and proteins. There are 20 standard amino acids encoded by DNA. Amino acids are linked together by peptide bonds during synthesis to form peptide chains.
Amylin
A 37-amino-acid peptide hormone co-secreted with insulin from pancreatic beta cells. Amylin analogues like
cagrilintide are studied in metabolic regulation research for their effects on gastric emptying and glucagon signaling.
Agonist
A molecule that binds to a receptor and activates it, producing a biological response. Many research peptides are receptor agonists — for example, semaglutide is a GLP-1 receptor agonist, and PT-141 is a melanocortin receptor agonist.
B
Bacteriostatic Water
Also: BAC water, BW
Sterile water containing 0.9% benzyl alcohol as a preservative. The standard solvent for reconstituting lyophilized peptides. The benzyl alcohol inhibits microbial growth, allowing multi-use from a single vial over days to weeks. Not to be confused with sterile water for injection, which contains no preservative.
Bioavailability
The fraction of an administered compound that reaches systemic circulation in active form. Subcutaneous injection provides higher bioavailability for most peptides compared to oral administration, because peptides are susceptible to enzymatic degradation in the GI tract.
BPC-157
Body Protection Compound-157
A 15-amino-acid peptide fragment derived from human gastric juice protein. One of the most widely studied cytoprotective peptides in preclinical literature.
Available at Pepta Labs with third-party COA.
C
CAS Number
A unique numerical identifier assigned by the Chemical Abstracts Service to every chemical substance. CAS numbers are used to unambiguously identify peptides across vendors, publications, and databases. Every Pepta Labs product page lists the compound's CAS number.
Certificate of Analysis (COA)
A document reporting the analytical test results for a specific batch of peptide. A quality COA includes the batch number, HPLC purity percentage, mass spectrometry molecular weight, date of testing, and name of the testing laboratory.
Third-party COAs from independent labs are more reliable than internal-only documentation.
CJC-1295
A synthetic GHRH (growth hormone-releasing hormone) analogue with 30 amino acids. Often studied with or without DAC (Drug Affinity Complex), which extends its half-life. Part of the
GH secretagogue research category.
Compounding Pharmacy
A pharmacy that custom-prepares medications for individual prescriptions under federal compounding laws. The FDA has increasingly restricted peptide compounding since 2024, particularly for GLP-1 agonists after the semaglutide shortage was declared resolved in February 2025.
Cytoprotective
Describing a compound that protects cells from damage or stress. BPC-157 and TB-500 are classified as cytoprotective peptides based on preclinical research in animal models of tissue injury. See the
cytoprotective peptide category.
D
DSIP
Delta Sleep-Inducing Peptide
A 9-amino-acid neuropeptide studied in sleep architecture research. Observed to modulate delta-wave EEG activity in preclinical models. Part of the
nootropic peptide category.
Dual Agonist
A peptide that activates two different receptor types simultaneously. Tirzepatide is a dual GIP/GLP-1 receptor agonist, meaning it binds to and activates both receptors. Dual agonism is studied for potential synergistic metabolic effects compared to single-receptor targeting.
E
Electrospray Ionization (ESI)
An ionization technique used in mass spectrometry to analyze peptides. ESI converts peptide molecules into gas-phase ions, allowing precise measurement of molecular weight. ESI-MS is standard in peptide quality control for identity confirmation.
Epithalon
Epitalon, Epithalamin
A synthetic tetrapeptide (Ala-Glu-Asp-Gly) studied for its observed effects on telomerase activation in preclinical models. Part of the
geroprotection research category.
F
Fmoc
9-Fluorenylmethyloxycarbonyl
A protecting group used in solid-phase peptide synthesis (SPPS). Fmoc chemistry is the most common modern approach to peptide synthesis, allowing amino acids to be added sequentially while protecting reactive side chains from unwanted reactions.
Freeze-Drying
See Lyophilization.
G
GHK-Cu
Copper Peptide GHK-Cu
A naturally occurring copper-binding tripeptide (Gly-His-Lys) complexed with copper (II). One of the most published signaling peptides, studied in collagen synthesis, extracellular matrix remodeling, and wound biology.
Available at Pepta Labs.
GLP-1
Glucagon-Like Peptide-1
An incretin hormone that stimulates insulin secretion in a glucose-dependent manner. GLP-1 receptor agonists like semaglutide and tirzepatide are among the most commercially significant peptide therapeutics. Research-grade GLP-1 agonists are available in the
metabolic regulation category.
GMP
Good Manufacturing Practice
A set of manufacturing quality standards enforced by the FDA for pharmaceutical products. Research peptides are not required to meet GMP standards (they are not drugs), but some vendors reference GMP-aligned or ISO-certified manufacturing processes as quality indicators.
GHRH
Growth Hormone-Releasing Hormone
A hypothalamic peptide that stimulates GH secretion from the anterior pituitary. Synthetic GHRH analogues like CJC-1295 and Sermorelin are used in endocrinology research. See
GH secretagogues.
H
Half-Life
The time required for the concentration of a peptide in a biological system to decrease by 50%. Peptide half-lives vary dramatically — from minutes (native GLP-1) to days (semaglutide, which is lipidated to extend its half-life to ~7 days).
HPLC
High-Performance Liquid Chromatography
The gold-standard analytical technique for measuring peptide purity. HPLC separates a sample into its constituent compounds by passing it through a chromatographic column under high pressure. The resulting chromatogram shows the target peptide peak as a percentage of total peak area. All Pepta Labs products are verified at
≥99% HPLC purity by independent third-party laboratories. See our
quality assurance page for details.
I
In Vitro
Latin for "in glass." Refers to research conducted outside a living organism, typically in test tubes, cell cultures, or other laboratory apparatus. All Pepta Labs products are sold for in-vitro research use only.
Ipamorelin
A synthetic pentapeptide GH secretagogue that selectively stimulates GH release via the ghrelin receptor (GHSR) without significantly affecting cortisol or prolactin. One of the most selective GH secretagogues in the research literature.
Available at Pepta Labs.
L
Lyophilization
Also: Freeze-drying
A dehydration process that removes water from a peptide solution by freezing it and then sublimating the ice under vacuum. The resulting lyophilized powder is significantly more stable than liquid peptide, allowing storage at -20°C for extended periods. All Pepta Labs peptides ship as lyophilized powder and must be
reconstituted before use.
Lot Number
Also: Batch number
A unique identifier assigned to a specific production batch of peptide. Lot numbers enable traceability — the lot number on your vial label should match the lot number on the accompanying COA. If they don't match, the COA doesn't apply to your product.
M
Mass Spectrometry (MS)
An analytical technique that measures the mass-to-charge ratio of ions. In peptide analysis, MS is used to confirm molecular identity by verifying that the observed molecular weight matches the theoretical molecular weight of the target sequence. MS complements HPLC: HPLC measures how pure, MS measures what it is.
Melanocortin Receptor
MC1R, MC3R, MC4R, MC5R
A family of G protein-coupled receptors involved in pigmentation, energy homeostasis, and reproductive function. MC1R regulates melanin synthesis. MC3R and MC4R are expressed in the hypothalamus. Research peptides like Melanotan-I, Melanotan-II, and PT-141 are melanocortin receptor agonists. See the
melanocortin category.
MOTS-c
A mitochondria-derived peptide encoded by the 12S rRNA gene. Studied in metabolic regulation and exercise biology research for its observed effects on AMPK signaling and glucose metabolism. Part of the
geroprotection category.
N
NAD+
Nicotinamide Adenine Dinucleotide
A coenzyme central to cellular energy metabolism. NAD+ precursors like NMN (nicotinamide mononucleotide) are studied for their role in maintaining NAD+ levels, which decline with age. NMN research has focused on sirtuin activation and mitochondrial function.
Neuropeptide
A peptide that acts as a signaling molecule in the nervous system. Neuropeptides influence neurotransmitter release, receptor sensitivity, and synaptic plasticity. Research examples include Semax (ACTH analogue), Selank (tuftsin analogue), and DSIP. See the
nootropic peptide category.
O
Off-Label Use
Use of an FDA-approved drug for a purpose, population, or dosage other than what it was approved for. While physicians may prescribe drugs off-label, research peptides sold as "not for human use" are distinct from off-label pharmaceuticals.
P
Peptide
A chain of amino acids linked by peptide bonds. Peptides are typically defined as chains of 2–50 amino acids, while longer chains are classified as proteins. Peptides serve diverse biological functions including hormone signaling, immune modulation, and neurotransmission.
Peptide Bond
A covalent chemical bond formed between the carboxyl group of one amino acid and the amino group of another, with the loss of a water molecule (condensation reaction). Peptide bonds are the links that connect amino acids into peptide chains.
PubMed ID (PMID)
A unique identifier assigned to each article indexed in the PubMed database of biomedical literature. Every study citation on Pepta Labs product pages includes a PMID for direct verification. Example format: PMID: 12345678.
Purity
The percentage of the desired compound in a peptide sample, as measured by HPLC. Higher purity means fewer synthesis byproducts, truncated sequences, or contaminants. Research-grade peptides should be ≥98% purity; premium suppliers deliver ≥99%. See
understanding purity in our research guide.
R
Reconstitution
The process of dissolving a lyophilized peptide in a solvent (typically bacteriostatic water) to create a solution for research use. Proper reconstitution involves injecting solvent slowly against the vial wall and swirling gently — never shaking. See our
reconstitution guide.
Retatrutide
A synthetic triple agonist peptide targeting GLP-1, GIP, and glucagon receptors simultaneously. Studied in Phase 2/3 clinical trials for metabolic pathway modulation.
Available at Pepta Labs as a research compound.
RUO
Research Use Only
A regulatory designation indicating that a product is intended exclusively for laboratory research and is not approved for human or animal use, medical treatment, or diagnostic purposes. All Pepta Labs products are sold as RUO.
S
Semaglutide
A GLP-1 receptor agonist peptide with a modified amino acid sequence and fatty acid side chain that extends its half-life to approximately 7 days. One of the most commercially significant peptides in history.
Research-grade semaglutide is available at Pepta Labs.
Semax
A synthetic heptapeptide and ACTH(4-10) analogue studied in neuropharmacology research. Observed to modulate BDNF expression and monoamine neurotransmitter levels in preclinical models. Part of the
nootropic peptide category.
Solid-Phase Peptide Synthesis (SPPS)
The standard method for manufacturing synthetic peptides. In SPPS, amino acids are sequentially coupled to a growing peptide chain that is anchored to an insoluble resin. After synthesis is complete, the peptide is cleaved from the resin and purified. Fmoc chemistry is the most common SPPS approach.
Subcutaneous Injection
SubQ
Injection into the tissue layer between the skin and muscle. The most common administration route for peptide therapeutics in clinical settings. Research peptides sold by Pepta Labs are for laboratory use only and are not intended for injection.
T
TB-500
Thymosin Beta-4 Fragment
A synthetic peptide corresponding to the active region of Thymosin Beta-4, a 43-amino-acid protein involved in cell migration and cytoskeletal organization. Studied extensively in preclinical tissue biology.
Available at Pepta Labs.
Third-Party Testing
Analytical testing performed by an independent laboratory that has no financial relationship with the vendor. Third-party testing eliminates the conflict of interest inherent in internal-only testing and is considered the gold standard for peptide quality verification. Pepta Labs uses third-party testing on
every batch.
Tirzepatide
A synthetic dual GIP/GLP-1 receptor agonist peptide. The first approved dual incretin agonist, with branded formulations studied in multiple Phase 3 clinical trial programs.
Research-grade tirzepatide is available at Pepta Labs.
Triple Agonist
A peptide that activates three different receptor types simultaneously. Retatrutide (GLP-1/GIP/glucagon) is the most advanced triple agonist in the research pipeline. Triple agonism is hypothesized to produce metabolic effects beyond what dual or single agonists achieve.
V
Vial
A small sealed container used to store and ship lyophilized peptide. Research peptide vials are typically sealed with a rubber stopper and aluminum crimp cap. The vial label should include the peptide name, dosage, batch/lot number, and "research use only" designation.
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