Information desk
Questions at the information desk.
Each answer comes from a Moleculine stop and links to it for the full route.
What is a peptide?
A peptide is a short chain of amino acids. Most peptide hormones are too large and too water-loving to pass through a cell membrane, so they bind a receptor on the surface and the receptor carries the message in. A signal starts at the surface explains how.
Why do most peptides need a needle?
A swallowed peptide meets stomach acid, digestive enzymes that cut peptide bonds and a gut wall that blocks large molecules, so very little reaches the blood. Oral semaglutide works only with an absorption enhancer. See why most peptides need a needle.
Is retatrutide approved?
No. Retatrutide is a triple agonist of the GIP, GLP-1 and glucagon receptors that is still in clinical trials, so no country has an authorized product and vials sold online are unapproved. The retatrutide stop covers its status and the approved alternatives.
What does 98% purity on a certificate mean?
It is usually an HPLC result: the main peak as a share of everything the detector saw. It misses salts, water and impurities that run with the product, and identity needs a separate mass test. Reading a purity number walks through a certificate.
Why are peptides freeze-dried and kept cold?
Water slowly breaks peptides apart through hydrolysis, deamidation, oxidation and clumping. Freeze-drying removes the water and cold slows what is left, which is why vials ship as a dry cake. Why freeze-dried, why cold explains each reaction.
Does Moleculine give doses?
No personal dosing advice. A stop may quote the label dose of an approved medicine with the label cited and describe what studies used in general terms. For unapproved compounds it says that no established human dose exists. The editorial policy sets out the rule.
What are fare zones?
Zones sort stops by difficulty, not importance: Zone 1 needs no background, Zone 2 assumes you know receptors and peptide bonds, Zone 3 goes into mechanism and caveats. The planner lists what to read before any stop.
Last updated 28 Oct 2026. See also the editorial policy, the privacy policy and how to read the map.