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Compound families

Peptides are not a random list. They cluster into families — by the receptor they act on, the protein they were cut from, or the chemical trick used to build them. Knowing which family something belongs to explains far more than its name does, and it explains why certain compounds are studied, and supplied, together.

GHRH analogues

All copy the same natural hormone and hit the same receptor.

Growth-hormone-releasing hormone is a 44-amino-acid hormone made in the hypothalamus. It binds the GHRH receptor on the pituitary, which is the switch for growth-hormone release. Each compound in this family is a version of that hormone, differing in how much of the sequence is kept and how it is protected from enzymes. Sermorelin keeps the first 29 residues — the shortest piece that still activates the receptor. Tesamorelin keeps all 44 and adds a chemical group at one end to slow breakdown. CJC-1295 DAC adds a group that latches onto albumin in blood, extending its life from minutes to days.

Ghrelin-receptor peptides

A different receptor that reaches the same pituitary output.

Ghrelin is the hormone best known for signalling hunger, and it acts at a receptor called GHS-R1a. That receptor also sits on the pituitary and influences growth-hormone release — by a separate route from the GHRH receptor above. Ipamorelin is a five-amino-acid synthetic that activates GHS-R1a selectively, which is what makes it useful as a laboratory tool: it isolates that one pathway from the others. Because the two families act on different receptors, they are frequently studied together, and that is why one of the blends pairs them.

The IGF axis

What growth hormone actually acts through, one step later.

Growth hormone does much of its work indirectly: it prompts the liver to produce insulin-like growth factor 1, a 70-amino-acid protein that carries the signal onward. In the body IGF-1 is held in check by binding proteins that switch it off. IGF-1 LR3 is an engineered version with a 13-residue extension and one substitution at position 3, changes that sharply reduce that binding. It sits downstream of the two families above rather than alongside them.

Cytoskeletal and tissue-model peptides

Both are short fragments of much larger proteins, studied in cell migration.

The cytoskeleton is the internal scaffolding a cell uses to hold its shape and to move. Thymosin β4 is a protein that helps manage it, and TB-500 is the seven-residue piece that does the actin binding. BPC-157 is a fifteen-residue sequence reported by its originating laboratory as part of a larger protein in gastric juice — a parent that has not been independently isolated. The two are unrelated in sequence but are studied in overlapping assays, which is why they appear together in a blend.

Melanocortin fragments

The smallest working piece of a pigment-and-inflammation hormone.

Alpha-melanocyte-stimulating hormone is a 13-residue hormone involved in pigmentation and in inflammatory regulation. Its final three residues — lysine, proline, valine — retain activity in inflammatory signalling assays without the pigmentation activity of the whole hormone. That separation is exactly why the fragment is useful in the laboratory: it isolates one arm of the hormone's behaviour.

Metal-binding peptides

A peptide defined as much by the metal it carries as by its sequence.

Some short peptides bind metal ions tightly enough that the complex, not the peptide alone, is the molecule of interest. GHK is three amino acids found in human plasma; it binds copper(II) with high affinity, and the resulting complex is what laboratories study in extracellular-matrix and connective-tissue work. Written GHK-Cu, the suffix denotes the bound copper.

PGP-stabilised neuropeptides

Two unrelated fragments given the same protective tail.

This is a design family rather than a biological one, and it is a neat piece of chemistry. Short peptides are broken down quickly by enzymes in the body. Researchers in Russia addressed this by attaching a proline-glycine-proline tail, which resists that breakdown. Semax applies it to a fragment of adrenocorticotropic hormone; Selank applies it to tuftsin, a fragment of an antibody molecule. The starting fragments are unrelated — the shared tail is what makes them siblings.

Mitochondrial-derived peptides

Coded by the mitochondria's own DNA, not the cell nucleus.

Almost every protein in a cell is coded by nuclear DNA. Mitochondria carry a small separate genome, and a handful of short peptides are encoded within it — a class only identified in the last two decades. MOTS-c, sixteen residues coded inside the 12S ribosomal RNA gene, was among the first. It is studied as a signalling molecule between the mitochondria and the rest of the cell.

Incretin-receptor agonists

One molecule engineered to act at several metabolic receptors at once.

Incretins are gut hormones released after eating that act on receptors regulating metabolism. A long-running line of research has built synthetic peptides that activate more than one of these receptors from a single molecule. Retatrutide is a triple agonist — GIP, GLP-1 and glucagon receptors together — and carries a fatty-acid modification that extends its half-life. It is investigational and has not been approved by any regulatory authority.

Coenzymes (not peptides)

Included for completeness — a different class of molecule entirely.

NAD+ is not a peptide and has no amino acids in it. It is a coenzyme present in every living cell, carrying electrons between chemical reactions and acting as a substrate for enzyme families including the sirtuins and PARPs. It appears in this catalog as a standard laboratory reagent rather than as a member of any peptide family.

Why some items are supplied as blends

Several catalog items arrive as a single vial containing more than one compound. A blend is a convenience of packaging, not a distinct substance: it has no CAS number, no molecular formula and no molecular weight of its own, because it is a mixture. Component identity, ratios and per-component purity are given on the lot certificate of analysis.

A laboratory isolating a single variable orders single compounds — a result from a mixture cannot be attributed to any one component. Blends are listed here so that anyone reading the catalog understands what they are, and what they are not.

A note on how this page is organised

These families group compounds by shared biology and chemistry — what the molecules are and where they came from. They are not groupings by application or outcome. Every compound in this catalog is supplied for in vitro laboratory research only, is not approved by the FDA for any use in humans or animals, and may not be administered to either.

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