Buying research peptides in Australia

Types of Peptides: A List of the Main Classes and Examples

Types of peptides are usually sorted four ways: by size, by shape, by where they come from, and by the job they do in the body's chemistry. A peptide is a chain of amino acids held together by peptide bonds. Proteins are the same idea on a much larger, folded scale. This guide walks through each of the four ways with real, named examples for each group.

Updated 26 October 2026. Education for laboratory research. Not medical advice.

At a glance

Think of the four ways as four questions. Any single peptide has an answer to each one, so it sits on all four maps at once.

Sorted by	Groups	Example	Why it fits
Size	dipeptide, tripeptide, oligopeptide, polypeptide	carnosine, a dipeptide	two amino acid units
Shape	linear, branched, cyclic	oxytocin, a ring	two cysteines bond to close a loop
Origin	body, food, microbes, lab	glutathione, found in many foods	made by cells and present in plant and animal tissue
Job	hormone, messenger, defence, carrier	insulin, a hormone	travels in the blood to act on distant tissue

The sections below take each row in turn.

Sources: US National Library of Medicine, MeSH descriptor: Peptides (D010455). US National Library of Medicine, MeSH descriptor: Dipeptides (D004151). PubChem compound record CID 439224 (carnosine), US National Library of Medicine. PubChem compound record CID 124886 (glutathione), US National Library of Medicine. PubChem compound record CID 439302 (oxytocin), US National Library of Medicine. Jones DP et al, Nutr Cancer, 1992.

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Sorted by size

Size is the oldest way to name peptides, and the prefixes tell you the count.

Name	Amino acids	Example
Dipeptide	2	carnosine
Tripeptide	3	glutathione, GHK-Cu, KPV
Oligopeptide	about 2 to 12	oxytocin, with 9
Polypeptide	about 13 or more	insulin, with 51 across two chains

These ranges come from the National Library of Medicine's subject headings. Oligopeptides have about 2 to 12 amino acids. Polypeptides have about 13 or more. No single number marks where a polypeptide ends and a protein begins. Proteins are simply the larger versions. They fold into complex machines such as enzymes and receptors.

Insulin shows how close the line can be. It has a B chain of 30 amino acids and an A chain of 21. Bonds between sulfur atoms join the two chains.

Sorted by shape

A chain of amino acids can stay open, split, or join back on itself.

Linear: an open chain with two free ends. BPC-157, a 15 amino acid sequence, is one.
Branched: a chain with a side branch attached partway along. The subject heading for peptides lists this as one of the three basic shapes.
Cyclic: the chain closes into a ring. Oxytocin is a ring formed by a link between two cysteines. Gramicidin S is a ring made only of peptide bonds. MT-2 is a chain of seven amino acids. Its last six close into a ring through a lactam bridge.

Shape matters to chemists because a ring has no loose ends. The library's heading for cyclic peptides adds one more point. Some are made by microbes without the usual protein building machinery.

Sources: US National Library of Medicine, MeSH descriptor: Peptides (D010455). US National Library of Medicine, MeSH descriptor: Peptides, Cyclic (D010456). PubChem compound record CID 439302 (oxytocin), US National Library of Medicine. PubChem compound record CID 73357 (gramicidin S), US National Library of Medicine. PubChem compound record CID 9941957 (BPC-157), US National Library of Medicine. PubChem compound record CID 92432 (melanotan II), US National Library of Medicine.

Sorted by origin

Peptides can also be grouped by where they come from.

Made in the body. Insulin and oxytocin are both made by human cells. So is glutathione, which almost every cell builds for itself.
Present in food. Plant and animal tissues carry peptides too. A 1992 food survey found glutathione across a typical diet. Levels varied a lot between food groups.
Made by microbes and other living things. Antimicrobial peptides are found across all kingdoms of life as part of natural defences.
Made in a lab. Chemists copy a natural peptide and then change it. Afamelanotide, sold to labs as MT-1, is the skin hormone alpha-MSH with two amino acids swapped.

A 2021 review traces this history. Most of its authors were researchers in Queensland and New South Wales. Early peptide medicines copied human hormones. Later ones came from nature, including animal venoms, and from rational design.

Sources: PubChem compound record CID 124886 (glutathione), US National Library of Medicine. PubChem compound record CID 439302 (oxytocin), US National Library of Medicine. Muttenthaler M, King GF, Adams DJ, Alewood PF, Nat Rev Drug Discov, 2021. Bin Hafeez A et al, Int J Mol Sci, 2021. Jones DP et al, Nutr Cancer, 1992. PubChem compound record CID 16197727 (afamelanotide), US National Library of Medicine.

Sorted by job

Here the groups describe biology only: the part each peptide plays in cells and tissues.

Group	What the group means	Examples
Peptide hormones	made from amino acids and act across the whole body	insulin
Neuropeptides	released by nerve cells as messengers between cells	neuropeptide Y; oxytocin, which also works as a messenger in the brain
Antimicrobial peptides	small peptides in early defences against microbes, most carrying a positive charge	LL-37, made by humans; magainins, made by frogs
Cell-penetrating peptides	able to cross the cell membrane and carry other molecules in	Tat, from an HIV protein, and penetratin, two of the first found
Copper-binding peptides	hold a copper ion inside a short chain	GHK-Cu

Medicine has used peptide hormones since insulin therapy began in the 1920s. A 2018 review counted more than 60 peptide drugs approved in the United States and other major markets.

Sources: PubChem compound record CID 439302 (oxytocin), US National Library of Medicine. Lau JL, Dunn MK, Bioorg Med Chem, 2018. Bin Hafeez A et al, Int J Mol Sci, 2021. Oliveira Júnior NG et al, Nat Rev Microbiol, 2025. Guidotti G, Brambilla L, Rossi D, Trends Pharmacol Sci, 2017. US National Library of Medicine, MeSH descriptor: Neuropeptides (D009479). US National Library of Medicine, MeSH descriptor: Peptide Hormones (D036361). US National Library of Medicine, MeSH descriptor: Antimicrobial Peptides. US National Library of Medicine, MeSH descriptor: Cell-Penetrating Peptides (D057846). PubChem compound record CID 139035031 (copper tripeptide, GHK-Cu), US National Library of Medicine. Prochiantz A, Methods Mol Biol, 2011.

Skincare peptides

Skincare labels use their own set of peptide groups. A 2009 review of topical skin peptides sorted them into four categories:

signal peptides
enzyme-inhibitor peptides
neurotransmitter-inhibitor peptides
carrier peptides

These are names for cosmetic ingredient groups, used by formulators. They say nothing about whether a product does anything, and we make no such claim.

Sources: Gorouhi F, Maibach HI, Int J Cosmet Sci, 2009.

Medicine or research

The same chemistry can sit on two very different shelves. An approved peptide medicine has been assessed by a regulator. It is entered on the Australian Register of Therapeutic Goods (ARTG). A research peptide has not been through either step.

The TGA issued a safety alert in April 2026. In it, the TGA notes that it has not assessed the safety, quality or effectiveness of unapproved peptide products. Its named examples include BPC-157, GHK-Cu, TB-500, retatrutide and CJC-1295. The TGA also says a research use label does not, on its own, make supply lawful. Is any peptide safe for a person? The honest answer is that the regulator has not assessed these products. A registered health professional is the right person to ask.

Sources: Therapeutic Goods Administration, Understanding your responsibilities when importing, compounding and supplying unapproved peptide products, Safety advisory, 13 April 2026.

Our research areas

Here is where each Glow Labs research area sits on the map above.

Research area	Examples	Where they sit
Beauty research	GHK-Cu, AHK-Cu	copper-binding tripeptides
Repair research	BPC-157, KPV	a 15 unit linear chain; a tripeptide
Longevity research	glutathione	a tripeptide cells make
Melanocortin research	MT-1, MT-2	lab-made alpha-MSH analogues, one linear and one cyclic
Metabolic research	retatrutide, tirzepatide	lab-made polypeptides of 39 units; tirzepatide targets two hormone receptors and retatrutide three
Hormone research	CJC-1295, ipamorelin, tesamorelin, kisspeptin-10	CJC-1295 is built on the first 29 units of growth hormone releasing hormone, and tesamorelin on all 44; ipamorelin is a five unit chain; kisspeptin-10 is a ten unit oligopeptide matching the last ten units of the 54 unit kisspeptin
Cognitive research	Semax, Selank, DSIP	short chains of 7 to 9 units; Semax extends a fragment of the hormone ACTH, and the library files DSIP as a neuropeptide

Not everything a peptide shop stocks is a peptide. Some research compounds are small molecules or coenzymes with no amino acid chain at all. Each guide says so where it applies. You can browse the full shop by area.

Research use only

Glow Labs supplies these compounds as lyophilised powder for laboratory research only. They are not medicines, supplements or cosmetics, and they are not for people or animals. Orders leave our Traralgon base in Gippsland during afternoon business hours, with fast delivery and tracking, 2-3 days. See shipping for the details, and how purity is tested for what a certificate shows.

FAQ

Are peptides and proteins the same?

They are built the same way, from amino acids joined by peptide bonds. Proteins are the larger versions that fold into complex shapes such as enzymes and receptors.

Is glutathione a peptide?

Yes. Glutathione is a chain of three amino acids, glutamate, cysteine and glycine, and almost every cell makes it.

What are the types of peptides for skin?

A 2009 review of topical peptides used four cosmetic groups: signal, enzyme-inhibitor, neurotransmitter-inhibitor and carrier peptides. These are ingredient categories, not proof of any effect.

Are peptides safe?

We do not make safety claims either way. The TGA says it has not evaluated unapproved peptide products for safety, quality or effectiveness.

Sources: US National Library of Medicine, MeSH descriptor: Peptides (D010455). PubChem compound record CID 124886 (glutathione), US National Library of Medicine. Gorouhi F, Maibach HI, Int J Cosmet Sci, 2009. Therapeutic Goods Administration, Understanding your responsibilities when importing, compounding and supplying unapproved peptide products, Safety advisory, 13 April 2026.