TB-500 vs KPV: two research peptides compared

TB-500 and KPV are two unrelated research peptides that happen to sit next to each other in blend listings. TB-500 is the synthetic form of thymosin beta-4's active region, a large peptide at 4963.44 g/mol. KPV is three amino acids, lysine, proline and valine, taken from the end of alpha-melanocyte-stimulating hormone, at 353.42 g/mol. They differ in origin, size and research context, and the only place they share a vial is the four-peptide KLOW blend.

TB-500 vs KPV side by side

TB-500 comes from thymosin beta-4, a protein that binds G-actin and appears in actin and cell-migration research models. KPV belongs to the melanocortin family through alpha-MSH, which puts it near the melanotan peptides on a family tree, though researchers study it in a different context. Neither molecule is a variant of the other, and the name TB-500 says nothing about KPV.

Why the size gap changes the math

TB-500 weighs about fourteen times as much as KPV. That matters as soon as you work in molar units.

• A 5 mg TB-500 vial is about 1 micromole.
• A 10 mg KPV vial is about 28.3 micromoles.

The same milligram figure holds very different numbers of molecules. If you swap one peptide for the other at the same mg/mL, the molecule count shifts by a factor of about fourteen. The TB-500 handling guide and the KPV handling guide each have a concentration table and a calculator preset.

The short piece of TB-500 sold separately is fragment 17-23 (LKKTETQ, 729.83 g/mol), not KPV. TB-500 vs TB-500 fragment 17-23 covers that pair.

TB-500 and GHK-Cu together

People who search for TB-500 and KPV often also want TB-500 and GHK-Cu in the same vial. GHK-Cu is a copper-bound tripeptide (glycyl-histidyl-lysine) at 403.91 g/mol, close in size to KPV and far smaller than TB-500. The catalog has no two-peptide TB-500 + GHK-Cu vial. There are two blends that contain both, or you can buy two single vials.

What is a peptide blend? explains the format. For a vial that holds both molecules, check four things:

• Two mass targets. The report should show TB-500 near 4963.44 and GHK-Cu near 403.91, plus a line for each other component.
• A batch ratio. The label mass on a blend is the combined content. The report states how it splits for that batch.
• Colour. A solution containing GHK-Cu turns blue, because copper(II) absorbs red light. This doesn't replace the report, but a colourless solution from a GHK-Cu blend is worth checking against it.
• Light. Copper complexes are light-sensitive, so keep any reconstituted solution with GHK-Cu out of direct light.

A blend fixes the ratio. Separate vials leave it adjustable and give each peptide its own report. Peptide blends vs single vials covers that choice.

Handling and checking either peptide

Both ship lyophilized and reconstitute the same way: bacteriostatic water down the inside wall of the vial, a gentle swirl, no shaking. Store the dry powder in the freezer long term. Once reconstituted, keep it in the fridge and split it into aliquots rather than refreezing.

On the report, the checks are the same for each:

1. An observed mass near the expected value, 4963.44 for TB-500 or 353.42 for KPV
2. HPLC purity at 99% or higher
3. A batch number that matches the vial
4. A named, independent lab

How to read a peptide lab report explains each line. Both are research chemicals, not approved drugs. Are research peptides legal in Canada? covers how Canada treats them.

Every TB-500, KPV and blend vial from pepuro ships free from our Calgary, Toronto and Vancouver distribution centers, dispatched the same business day your e-Transfer clears, with a QR code on the vial that opens its independent, third-party lab report.

For research use only. Not for human or animal consumption.