10 Peptide Fun Facts Every Researcher Should Know

Palmetto Peptides Research Team

February 21, 2026

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Peptides have been a serious subject of biological research for well over a century, but the depth and breadth of what's been discovered about them remains surprising even to seasoned researchers. Behind the technical language and experimental protocols are some genuinely fascinating facts about these molecules — from the scope of their presence in nature to the surprising ways they've been discovered and applied.

Here are ten peptide facts that tend to stick with people once they learn them.

1. Insulin Was the First Peptide Drug, Isolated Over 100 Years Ago

In 1921, Frederick Banting and Charles Best at the University of Toronto isolated insulin from canine pancreatic tissue — the first peptide ever purified for therapeutic use. The following year, it was used to treat a 14-year-old boy with type 1 diabetes, transforming what had been a death sentence into a manageable condition. Banting received the Nobel Prize in Physiology or Medicine in 1923. The entire peptide drug industry traces its conceptual roots to that Toronto laboratory.

2. There Are Over 7,000 Naturally Occurring Peptides Identified in the Human Body

The human peptidome — the complete collection of peptides present in human tissues and fluids — is estimated to contain over 7,000 distinct compounds. These range from two-amino-acid dipeptides to complex signaling molecules with dozens of residues. Many remain poorly characterized, meaning the peptide field still has enormous territory to explore. Hormones, neurotransmitter modulators, antimicrobial compounds, and regulatory signals are all represented in this vast molecular inventory.

3. The GLP-1 Receptor Agonist Drug Class Was Inspired by Gila Monster Saliva

The class of peptides that includes semaglutide and tirzepatide traces its origin to a peptide found in the venom of the Gila monster (Heloderma suspectum). Exendin-4, isolated from Gila monster saliva in the 1990s, is a GLP-1 receptor agonist with roughly 50% structural homology to human GLP-1 — but with dramatically greater enzymatic stability. This discovery led to the development of exenatide, the first GLP-1 receptor agonist approved for clinical use, and ultimately to the entire class of incretin-based research compounds now being studied worldwide.

4. Some Peptides Are More Stable Than Others — By Design

One of the key challenges in peptide research is enzymatic degradation — proteases in biological fluids break down peptides quickly, limiting how long they can exert their effects. Researchers have developed multiple strategies to address this. Semaglutide, for example, has been engineered with a fatty acid side chain that allows it to bind albumin in the bloodstream, dramatically extending its half-life from minutes (like native GLP-1) to approximately seven days. Modified GRF 1-29 (CJC-1295 without DAC) was similarly engineered with specific amino acid substitutions that resist DPP-4 degradation. Engineering stability is as much a part of modern peptide design as identifying the sequence itself.

5. GHK-Cu Has Been Studied for Over 50 Years

Glycyl-L-histidyl-L-lysine copper complex — GHK-Cu — was first isolated from human plasma in 1973 by Dr. Loren Pickart at the University of California San Francisco. That makes it one of the longest-studied regenerative peptides in the research literature. Pickart spent decades characterizing its effects on wound healing, collagen synthesis, and gene expression before the broader research community picked up the compound. DNA microarray analysis published in 2018 by Pickart and Margolina documented GHK-Cu's influence on over 4,000 human genes — an extraordinary finding for a three-amino-acid peptide.

6. Some Peptide Discoveries Came From Research on Fasting

MOTS-C, one of the more recently characterized peptides in the longevity research space, was discovered through research on mitochondrial DNA. Scientists found that this mitochondria-derived peptide — encoded in the mitochondrial 12S rRNA gene — increases significantly during caloric restriction and exercise, mimicking some of the metabolic benefits of fasting. The discovery, published by Lee et al. in Cell Metabolism in 2015, opened a new research category: mitochondria-derived peptides (MDPs), which now includes several compounds being actively investigated for their role in metabolic health and aging.

7. Peptide Synthesis Technology Has Made Research Compounds Dramatically More Accessible

Solid-phase peptide synthesis (SPPS), developed by Robert Merrifield in the 1960s (for which he received the 1984 Nobel Prize in Chemistry), transformed peptide science by making it possible to synthesize arbitrary peptide sequences in a laboratory. Before SPPS, obtaining research quantities of a specific peptide required either isolating it from biological tissue (slow, expensive, limited) or using biological expression systems. Modern automated SPPS can produce peptides at ≥98% purity in quantities sufficient for research at a fraction of the historical cost, which is why the research peptide field has expanded so dramatically in recent decades.

8. BPC-157 Has One of the Largest Preclinical Research Bases of Any Research Peptide

With over 300 peer-reviewed studies published — primarily in rodent models — BPC-157 has an unusually deep evidence base for a research peptide. Most of this research has been conducted by Dr. Predrag Sikiric and colleagues at the University of Zagreb, who have systematically investigated the compound's effects across organ systems, injury types, and experimental conditions over more than three decades. This concentrated research output is relatively rare in the peptide field, where most compounds have much thinner preclinical profiles.

9. The Melanocortin System Regulates an Unusually Diverse Set of Functions

The melanocortin peptide system — which includes compounds like PT-141 and MT-2 — is one of the most functionally diverse peptide signaling systems in the body. Melanocortin receptors (MC1R through MC5R) regulate pigmentation, inflammation, energy balance, immune function, and neurological signaling. This remarkable diversity means melanocortin peptides are studied across dermatology, metabolism, neuroscience, and immunology research. The fact that a single peptide system governs such disparate physiological functions is a reminder of how interconnected biological regulation really is.

10. Peptide Research Is Currently Driving Some of the Most Significant Advances in Medicine

The GLP-1 receptor agonist class — which began as basic peptide research — is currently transforming the treatment of obesity and metabolic disease at a global scale. Semaglutide, tirzepatide, and the emerging triple agonist retatrutide represent what may be the most significant pharmaceutical development of the past decade. Meanwhile, peptide-based cancer immunotherapies, antimicrobial peptides to address antibiotic resistance, and peptide-drug conjugates for targeted cancer therapy represent other frontier applications. The peptide field, far from being a niche corner of pharmacology, is increasingly central to the most important research happening in biomedical science today.

Explore the Research Peptide Catalog

If this overview has sparked your interest in the peptide research space, Palmetto Peptides offers a comprehensive catalog of research-grade compounds at ≥98% purity. Browse our collections by category: Recovery, Metabolic, Anti-Aging, Muscle Growth, and Cognitive.

Key Citations

Muttenthaler M, et al. (2021). Trends in peptide drug discovery. Nature Reviews Drug Discovery, 20(4), 309–325.
Lee C, et al. (2015). The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism, 21(3), 443–454.
Pickart L, Margolina A. (2018). Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. International Journal of Molecular Sciences, 19(7), 1987.