Guide

What Are Peptides? A Beginner's Guide

Peptides are short chains of amino acids — the same building blocks proteins are made of, just smaller. That size difference turns out to matter a lot for biology, pharmacology, and the way peptides have come to dominate the research-compound space.

Peptide vs protein: where's the line?

Convention: fewer than ~50 amino acids is a peptide; longer than that is a protein. It's a soft line — insulin is 51 residues and is often called a peptide hormone. The functional difference is that shorter chains fold less, are often more stable, and can be chemically synthesized at scale. That last point matters: peptides can be manufactured by solid-phase synthesis rather than through living cell lines, which keeps research-grade material affordable.

How peptides signal

Most research peptides act by binding cell-surface receptors — the same way hormones do. GLP-1 agonists bind the GLP-1 receptor. GHRPs bind the ghrelin receptor. Melanocortin agonists bind MC1R/MC3R/MC4R/MC5R. The receptor determines the downstream effect, which is why a small difference in peptide structure can mean a completely different endpoint profile.

The main research families

Growth-axis peptides

GHRPs (GHRP-2, GHRP-6, ipamorelin, hexarelin) bind the ghrelin receptor and stimulate growth-hormone release. GHRH analogs (sermorelin, tesamorelin, CJC-1295) bind a separate receptor and produce the same outcome via a different route. The two classes are commonly stacked because activating both receptors produces stronger GH release than either alone.

Incretin peptides (GLP-1 class)

Semaglutide, tirzepatide, retatrutide, survodutide, mazdutide — these are the fat-loss / metabolic peptides that have dominated news cycles. They act on the GLP-1 receptor (and in some cases GIP and glucagon), affecting insulin secretion, gastric emptying, and central appetite regulation.

Repair and soft-tissue peptides

BPC-157 and TB-500 are the two most-studied compounds here. BPC-157 drives angiogenesis and has a huge rodent-model literature behind it. TB-500 promotes cellular migration. They hit different parts of the repair pathway, which is why stacks combining both are popular.

Cosmetic and skin peptides

GHK-Cu is the anchor — decades of literature in skin, hair, and wound research. Blends like GLOW and KLOW extend this with repair and anti-inflammatory peptides.

Cognitive / sleep peptides

Selank, semax, DSIP, pinealon — short peptides with nootropic, anxiolytic, or sleep-modulating profiles. Most of this literature comes from Russian research groups going back to the 1980s.

Longevity peptides

Epitalon (telomerase activation), NAD+ (sirtuin substrate), MOTS-c (mitochondrial signaling), SS-31 (mitochondrial membrane support). This is where the newest research keeps popping up.

Why peptides come as lyophilized powder

Peptides are unstable in solution at room temperature. Freeze-drying them (lyophilization) removes water and locks them in a stable form for shipping and storage. Researchers reconstitute with bacteriostatic water just before use. Unreconstituted vials stay stable for months to years in a freezer.

Certificate of analysis: what to look for

A COA is an independent lab report verifying that the vial contains what the label says. Key items: identity (mass spectrometry confirming the molecular weight), purity (HPLC showing the % main peak), and absence of common contaminants. Anything without a COA is a guess.

Reading a product label

Name + dose — "BPC-157 10mg" means 10 mg of BPC-157 total in the vial.
Format — vial (injectable), capsule (oral), or bulk powder.
Purity — % main peak by HPLC. 98%+ is the standard to expect.
Storage — room temp for unreconstituted, refrigerate once mixed.

Where to go next

The catalogue on Tidemaxxing is organised by research pathway rather than by compound name — if you know what endpoint you're researching, start there. If you know the compound name, the full catalogue has every vial indexed.