Read the chain.
A short orientation to peptide structure, the 20 amino acids, and how to read a sequence. Use the tools below to inspect any chain you're researching.
What is a peptide?
A peptide is a short chain of amino acids linked by peptide bonds. Anything from 2 to ~50 amino acids long is generally called a peptide; longer chains become proteins. Each residue contributes specific chemistry — hydrophobic, polar, charged — that shapes the molecule's function.
The 20 amino acids.
Hover any cell for properties. Color cues: cyan = polar, violet = hydrophobic, white = neutral.
Sequence builder.
Type a sequence (one-letter codes). The 3D model and molecular weight update live.
- Residues
- 7
- Molecular weight
- 824.99 Da
- Skipped chars
- 0
Peptide families.
Cosmetic peptides
Short sequences studied for skin-related research applications (e.g. signal peptides, carrier peptides).
Performance peptides
Sequences studied for metabolic and recovery-related research (e.g. growth-related peptides).
Neuropeptides
Peptides studied for receptor-binding and neurotransmission research.
Antimicrobial peptides
Short cationic sequences studied in antimicrobial and immune-related research.
Hormone analogs
Synthetic analogs of natural hormones, used in receptor research and pharmacology.
Custom research sequences
Bespoke sequences synthesized for a specific protocol. Not commonly catalog-listed.
TODO-COPY: refine family blurbs and add real example sequences per family.
Compound families by mechanism.
Research peptides are most usefully grouped not by catalog category but by mechanism — receptor target, signaling pathway, or structural lineage. The same compound can appear in multiple mechanism families. Below are the twelve mechanism families that organize the Nexus research catalog.
GLP-1 receptor agonists
Single- and multi-agonist analogs of glucagon-like peptide 1. Includes single GLP-1 agonists (semaglutide, liraglutide), dual GIP/GLP-1 agonists (tirzepatide), triple GLP-1/GIP/glucagon agonists (retatrutide), and GLP-1/glucagon dual agonists (mazdutide, survodutide). Common research applications: receptor pharmacology across the incretin axis, dose-format comparison studies, multi-pathway signaling research. Catalog GLP-1 metabolic.
Amylin pathway agonists
Long-acting amylin analogs paired with GLP-1 agonists in blend formats. Cagrilintide is the catalog representative, standalone and in cagri-sema (cagri + semaglutide) and retatrutide+cagrilintide blends.
Growth hormone-releasing hormone (GHRH) analogs
Synthetic GHRH-receptor agonists. Sermorelin acetate is the canonical short-acting research analog; CJC-1295 (with and without DAC) is the long-acting research analog. Tesamorelin is the most extensively-studied GHRH analog. Common research stack: GHRH + GHRP for pulsatile-signaling models. Catalog growth hormone secretagogues.
Growth hormone-releasing peptides (GHRPs / ghrelin agonists)
Ghrelin receptor agonists that complement GHRH analogs in pulsatile-signaling research. Ipamorelin is the selective research analog (GH-release without other pituitary effects); GHRP-2 and GHRP-6 are earlier- generation reference compounds; hexarelin is the hexapeptide research reference.
IGF-axis and HGH-fragment derivatives
Insulin-like growth factor 1 long-arg-3 variant (IGF-1 LR3), mechano growth factor (MGF) and its pegylated derivative (PEG-MGF), and human growth hormone fragment 176-191 with its AOD9604 derivative. Common research application: studying the GH/IGF axis at the effector rather than the secretagogue level.
Tissue-repair and healing peptides
Body Protection Compound 157 (BPC-157), thymosin beta-4 acetate (TB-500) and its active fragment (TB-500-frag), and blend formats combining these with GHK-Cu and KPV. Common research applications: tissue-repair models, angiogenesis research, gastrointestinal mucosal stability models. Catalog healing and recovery.
Copper-binding peptides
Glycyl-histidyl-lysine in its copper-chelated form (GHK-Cu), the alanine-substituted variant (AHK-Cu), and the unchelated GHK reference. Cosmetic and signaling research applications focused on extracellular matrix remodeling and fibroblast research models. Catalog cosmetic peptides.
Melanocortin receptor agonists
Alpha-melanocyte-stimulating hormone (α-MSH) analogs: melanotan I (MT-1), melanotan II (MT-2), bremelanotide (PT-141), and the alpha-MSH derivative tripeptide KPV. Research applications cover melanocortin-pathway pharmacology — pigmentation, melanocortin-4 receptor research, and signaling cascade work.
Khavinson short peptide bioregulators
A family of 15 short tetrapeptide (and some di-/tri- peptide) bioregulators originally described by V.Kh. Khavinson and colleagues in Russian biochemistry literature. Tissue-specific research history: lung (bronchogen, chonluten), cardiovascular (cardiogen, vesugen), cartilage (cartalax), CNS (cortagen, pinealon), immunological (crystagen, thymalin), hepatic (livagen), reproductive (ovagen, prostamax, testagen), pancreatic (pancragen), and pineal (epithalon). Catalog Russian bioregulators.
Mitochondrial-derived peptides (MDPs) and energy peptides
Mitochondrial open reading frame-derived peptides (humanin, MOTS-c), mitochondrial-targeted antioxidant peptides (SS-31 / elamipretide), AMPK activators (AICAR), NAD+-pathway compounds (NAD+ itself, 5-Amino-1MQ as NNMT inhibitor), and mitochondrial uncouplers (BAM15, SLU-PP-332 as ERR agonist). Common research focus: cellular bioenergetics and metabolic pathway research.
Nootropic and neurotrophic peptides
ACTH-fragment analogs (semax, NA-semax-amidate), TP-7-derived analogs (selank, NA-selank-amidate), spadin analogs (PE 22-28), Dvl PDZ-binding peptides (PTD-DBM), ciliary neurotrophic factor-derived peptides (P21 variants), and neuropeptide pools (cerebrolysin, DSIP). Research applications include receptor-binding studies and neurotrophic factor signaling research. Catalog cognitive and nootropic.
Antimicrobial and immune-modulating peptides
Human cathelicidin LL-37, the alpha-MSH-derived tripeptide KPV, and thymic peptides (thymosin alpha-1, thymalin). Common research applications: antimicrobial research, innate-immunity research, immune-modulation models.
Research peptide timeline.
A condensed timeline of the research peptide field, focused on milestones relevant to the compounds in the Nexus catalog.
- 1953 — Vincent du Vigneaud's synthesis of oxytocin demonstrates that biologically active peptides can be assembled by solid-phase chemistry. The Nobel Prize awarded in 1955 marks the start of synthetic peptide research as an enterprise.
- 1971-1973 — Andrew Schally and Roger Guillemin independently characterize hypothalamic- releasing hormones (including GHRH and TRH), establishing the secretagogue paradigm that underpins later research peptides like sermorelin and CJC-1295.
- 1970s-1980s — V.Kh. Khavinson's research group in St. Petersburg describes short tetrapeptide bioregulators, originating the Khavinson peptide family (epithalon, thymalin, cortagen, and the rest of the 15- compound research lineage now in the Nexus catalog). See the Khavinson PubMed corpus for the cross-language literature.
- 1991 — Pickart and Margolina publish on GHK-copper as a research signaling peptide, originating the copper-tripeptide research lineage.
- 1990s — Bowers and colleagues develop GHRPs (including GHRP-2 and GHRP-6), which later inform ipamorelin and the broader ghrelin- receptor research family.
- 1991-1998 — Sikiric and colleagues at the University of Zagreb begin publishing on BPC-157, originating the gastric pentadecapeptide research lineage. Subsequent two decades produce more than 100 published research studies on the compound.
- 2010s — discovery of mitochondrial-derived peptides (humanin in 2003, MOTS-c in 2015) opens the mitochondrial open-reading-frame research field.
- 2017-2024 — development of multi-agonist incretin peptides (semaglutide 2017, tirzepatide 2022, retatrutide and mazdutide and survodutide later) creates the largest contemporary research peptide family.
- 2020s — FOXO4-DRI and related senolytic research peptides establish a new research peptide category at the intersection of cellular senescence and longevity research.
Mechanism families × catalog categories.
Mechanism families and catalog categories overlap but don't map 1:1. The cross-reference below clarifies how the mechanism axis relates to the catalog axis.
| Mechanism family | Primary catalog category | Cross-listed categories |
|---|---|---|
| GLP-1 receptor agonists | GLP-1 & Metabolic | — |
| Amylin pathway agonists | GLP-1 & Metabolic | — |
| GHRH analogs | Growth Hormone Secretagogues | — |
| GHRPs / ghrelin agonists | Growth Hormone Secretagogues | — |
| IGF-axis & HGH-fragment | Growth Hormone Secretagogues | Specialty Research |
| Tissue repair / healing | Healing & Recovery | — |
| Copper-binding peptides | Cosmetic & Skin | Healing & Recovery (blend pairings) |
| Melanocortin agonists | Tanning & Pigmentation | Sexual Health (PT-141), Healing & Recovery (KPV) |
| Khavinson bioregulators | Russian Bioregulators | — |
| Mitochondrial-derived peptides | Longevity & Cellular Health | Mitochondrial & Energy |
| Energy & metabolic small molecules | Mitochondrial & Energy | Oral Tablets |
| Nootropic / neurotrophic | Cognitive & Nootropic | — |
| Antimicrobial / immune | Healing & Recovery | Russian Bioregulators (thymalin) |
Research peptide categories.
The Nexus Laboratory catalog is organized into 14 research-area categories. Each landing page lists the in-stock compounds for that area along with reference data.
- GLP-1 & MetabolicGLP-1, amylin, and multi-agonist metabolic research peptides.
- Growth Hormone SecretagoguesGHRH analogs, GH secretagogues, and growth-factor research compounds.
- Healing & RecoveryTissue repair, immune modulation, and recovery-oriented research peptides.
- Cosmetic & SkinCopper peptides and cosmetic signaling compounds.
- Russian BioregulatorsShort Khavinson-style bioregulator peptide catalog.
- Cognitive & NootropicNeuroactive, nootropic, and cognitive research compounds.
- Longevity & Cellular HealthMitochondrial, senolytic, and cellular health research compounds.
- Tanning & PigmentationMelanocortin and pigmentation research peptides.
- Sexual HealthPT-141, VIP, and related signaling research compounds.
- SleepSleep and circadian research compounds.
- Mitochondrial & EnergyEnergy metabolism, redox, and mitochondrial research compounds.
- Specialty ResearchSpecialized compounds outside the larger peptide families.
- Oral TabletsTablet and blend-format research compounds.
- Solvents & AccessoriesReconstitution solvents and accessory materials.
Featured research compounds.
Common reference points across the catalog. Each card links into the compound detail page; hover for the relationship note.
Pairs with bpc-157
Same category, mechanism overlap, and common research stack pairings.
Pairs with semaglutide
Same category, mechanism overlap, and common research stack pairings.
Pairs with cjc-1295-without-dac
Same category, mechanism overlap, and common research stack pairings.
Pairs with epithalon
Same category, mechanism overlap, and common research stack pairings.
Pairs with selank
Same category, mechanism overlap, and common research stack pairings.
Pairs with ghk-cu
Same category, mechanism overlap, and common research stack pairings.
Pairs with pt-141
Same category, mechanism overlap, and common research stack pairings.
Pairs with mots-c
Same category, mechanism overlap, and common research stack pairings.
Compound pairings are sourced from the curated D2 keyword strategy and D5 related-compounds data — see the lab-verified archive for the batch-level certificates of analysis behind these compounds.