Peptide Research Glossary

Agonist

A molecule that binds to a receptor and activates it, triggering the receptor's normal biological response. Most of the growth-hormone-axis and metabolic peptides in this catalogue, including Ipamorelin and Retatrutide, are studied as receptor agonists.

Amino Acid Sequence

The specific order of amino acids that make up a peptide. A peptide's sequence determines its structure and biological activity — even small changes to a sequence can significantly change how a compound behaves in research.

Analog

A synthetic compound designed to structurally resemble, and often extend or modify the activity of, a naturally occurring molecule. Tesamorelin, for example, is a stabilized analog of naturally occurring GHRH(1-44).

Angiogenesis

The formation of new blood vessels from existing ones. It's a mechanism frequently referenced in tissue-repair research, including BPC-157 research.

Anxiolytic

Reducing or preventing anxiety-like effects, typically studied in behavioral or preclinical research models. Selank is studied for anxiolytic-like effects.

Bacteriostatic Water (BAC Water)

Sterile water containing a small amount of benzyl alcohol as a preservative, commonly used in laboratory settings to reconstitute lyophilized peptides. See our reconstitution guide for more.

Cardiolipin

A phospholipid found almost exclusively on the inner mitochondrial membrane, where it helps organize the electron transport chain. SS-31 research centers on its interaction with cardiolipin.

Certificate of Analysis (CoA)

A document from an independent testing laboratory confirming a specific batch's measured purity, content, and identity. Every KYIN Peptides batch is tested by Janoshik — see our quality process for details.

Cytoprotection

The protection of cells from harmful agents or damage, commonly studied in gastrointestinal and mucosal-tissue research. BPC-157's discovery traces to cytoprotection research at the University of Zagreb.

Fragment

A shorter peptide sequence derived from a larger parent protein or peptide, often retaining a specific piece of the parent's biological activity. KPV is a fragment of alpha-MSH; TB-500 is derived from thymosin beta-4.

GHRH (Growth Hormone-Releasing Hormone)

A naturally occurring hormone that stimulates the pituitary gland to release growth hormone. See our GHRH & Growth Hormone research overview for the peptides studied along this pathway.

GHRP / Growth Hormone Secretagogue

A class of peptides that stimulate growth hormone release via the ghrelin receptor, a distinct pathway from GHRH. Ipamorelin is studied as a selective growth hormone secretagogue.

Half-Life (Biological)

The time it takes for half of a compound's concentration to be eliminated from a biological system. Much peptide-engineering work, such as the Pro-Gly-Pro stabilization used in Semax and Selank, is specifically aimed at extending an otherwise short biological half-life.

In Vitro

Research conducted outside a living organism, typically in a controlled laboratory environment such as a test tube or cell culture — distinguished from in vivo, meaning within a living organism. All KYIN Peptides products are sold for in vitro laboratory research use only.

Incretin

A class of hormones, including GLP-1 and GIP, released after eating that stimulate insulin secretion and help regulate blood glucose. Retatrutide is studied as a triple incretin/glucagon receptor agonist.

Lyophilized / Lyophilization

Freeze-dried; a process that removes water from a compound under vacuum to leave a stable, storable powder. Nearly every peptide in our catalogue ships in lyophilized form — see our storage guide for handling considerations.

Mitochondrial-Derived Peptide (MDP)

A peptide encoded within mitochondrial, rather than nuclear, DNA. MOTS-c was among the first mitochondrial-derived peptides discovered.

Molecular Weight

The mass of a molecule, usually expressed in daltons (Da), which affects a peptide's stability, solubility, and behavior in research applications.

Nootropic

Relating to effects on cognition, memory, or mental performance, typically studied in preclinical or behavioral models. See our Cognitive & Nootropic research overview.

Oxidative Stress

An imbalance between reactive oxygen species (free radicals) and an organism's ability to neutralize them, implicated in cellular-aging and mitochondrial-dysfunction research. SS-31 research centers on reducing oxidative stress at the mitochondrial membrane.

Peptide

A short chain of amino acids linked by peptide bonds, distinguished from a full protein primarily by length — typically under 50 amino acids.

Purity

The proportion of a sample that consists of the intended compound, typically measured via HPLC (high-performance liquid chromatography) and expressed as a percentage. Every product page publishes the current batch's tested purity.

Receptor Selectivity

The degree to which a compound activates its intended target receptor without triggering effects at other, related receptors. Ipamorelin's development specifically targeted improved receptor selectivity over earlier growth hormone secretagogues.

Reconstitution

The process of adding a liquid, typically bacteriostatic water, to a lyophilized peptide to return it to a usable solution for laboratory use. See our full reconstitution guide.

Research Use Only (RUO)

A labeling designation indicating that a product is intended strictly for laboratory research and has not been evaluated or approved for human or animal use, diagnosis, or treatment. Every product KYIN Peptides supplies is labeled and sold as RUO — see our Terms of Sale.

Secretagogue

A substance that stimulates secretion, most often used in this context to describe growth hormone secretagogues (see GHRP, above).

Telomerase

An enzyme that maintains the length of telomeres, the protective caps at the ends of chromosomes, and a mechanism frequently studied in cellular-aging research. Epitalon research centers on its effects on telomerase activity.

Triple Agonist

A compound engineered to activate three distinct receptor targets simultaneously. Retatrutide is studied as a GIP/GLP-1/glucagon triple receptor agonist — see its discovery history.

Tripeptide / Tetrapeptide / Pentapeptide / Heptapeptide / Pentadecapeptide

Terms describing a peptide's length by its number of amino acids: a tripeptide has 3 (e.g. KPV), a tetrapeptide has 4 (e.g. Epitalon, SS-31), a pentapeptide has 5 (e.g. Ipamorelin), a heptapeptide has 7 (e.g. Semax, Selank), and a pentadecapeptide has 15 (e.g. BPC-157).

Tuftsin

A naturally occurring immunomodulatory peptide first described in the 1970s, and the structural starting point for Selank's development.