Glossary

A

Acetate salt

The most common salt form of a research peptide. Acetic acid pairs with basic residues such as lysine and arginine during purification. It adds weight to the powder that is not peptide.See: Salt form Net peptide content

Acetylation

Adding an acetyl group, usually to the N-terminus. It removes the free amine and can slow breakdown. TB-500 is N-acetylated.See: N-terminus TB-500

Agonist

A molecule that binds a receptor and switches it on. Tirzepatide is an agonist at two receptors; retatrutide at three.See: Receptor

Albumin binding

Attaching a fatty chain or chemical hook so a peptide sticks to albumin in blood. It shields the peptide from kidneys and enzymes and stretches its half-life from minutes to days.See: DAC Half-life

Amidation

Ending a peptide with an amide (–NH₂) instead of an acid. Many natural hormones are amidated, and the change can protect against breakdown.See: C-terminus

Amino acid

One of the building blocks of a peptide. Twenty are coded by genes; synthetic peptides often use others, such as Aib or D-forms.See: Residue D-amino acid

Analogue

A peptide built from a natural one with deliberate changes, to make it last longer or bind more selectively. Tesamorelin is an analogue of GHRH.See: Fragment

Average mass

The mass of a molecule using the natural mix of isotopes for each element. It is the number used for weighing and for molarity.See: Monoisotopic mass Molarity

B

Bacteriostatic water

Sterile water with 0.9% benzyl alcohol, which stops bacteria growing. Used as a laboratory solvent.

C

C-terminus

The end of a peptide chain with the free carboxyl group. Written on the right by convention.See: N-terminus Amidation

CAS number

A unique number assigned by the Chemical Abstracts Service to a defined substance. Salt forms and complexes often have their own numbers.

Certificate of analysis

The lab report for one lot: what was tested, by which method, and the result. Ours lists purity by HPLC and identity by mass spectrometry.See: Lot How we test a lot

Chromatogram

The trace an HPLC run produces: detector signal against time. Each peak is a substance leaving the column.See: HPLC Retention time

Clinical trial phases

Phase 1 tests safety in a small group. Phase 2 tests whether it works and at what dose. Phase 3 confirms it in large groups before a licence.See: Placebo-controlled

D

D-amino acid

The mirror-image form of an amino acid. Natural proteins use L-forms; swapping in a D-form makes a peptide harder for enzymes to cut. Ipamorelin contains two.See: Amino acid

DAC

Drug Affinity Complex. A lysine carrying a maleimide group that bonds to albumin after injection. It is what separates CJC-1295 with DAC from the version without.See: Albumin binding CJC-1295

Disulfide bridge

A bond between two cysteine residues that holds part of a peptide in a loop. Many of the peptides in this library have none.

E

Electrospray ionisation

ESI. The way a peptide is given an electric charge so a mass spectrometer can weigh it. Large peptides pick up several charges at once.See: Mass spectrometry

F

Formula

The count of each element in one molecule, for example C₆₂H₉₈N₁₆O₂₂ for BPC-157.See: Average mass

Fragment

A short piece of a longer natural peptide or protein. KPV is a fragment of alpha-MSH; TB-500 of thymosin beta-4.See: Analogue

H

Half-life

The time for the amount of a substance in blood to fall by half. For natural peptides it can be minutes.See: Pharmacokinetics Albumin binding

HPLC

High-performance liquid chromatography. The sample is pushed through a packed column and its parts leave at different times. Used to measure purity.See: Reverse-phase Purity

I

Identity

Proof that the vial contains the molecule on the label. We confirm it by mass spectrometry.See: Mass spectrometry

In vitro

Done in a dish or test tube: cells, tissue or purified proteins outside a living body.See: In vivo

In vivo

Done in a living animal or person.See: In vitro

Isotope pattern

The cluster of peaks a molecule makes in mass spectrometry because some atoms are heavier isotopes. Copper peptides show a distinctive one.See: Mass spectrometry

L

Lot

One production run, tested as a unit and given one number. The number on your vial opens its certificate.See: Lot register

Lyophilisation

Freeze-drying. Water is removed under vacuum from frozen material, leaving a dry cake that keeps far better than a solution.

M

Mass spectrometry

A method that weighs molecules after giving them a charge. Used to confirm a peptide is what the label says.See: Electrospray ionisation Identity

Molarity

Concentration counted in molecules rather than mass: moles per litre. Uses the molecular weight to convert from mg/mL.See: Peptide calculator

Monoisotopic mass

The mass of a molecule made only of the most common isotope of each element. It is what a high-resolution mass spectrometer sees as the first peak.See: Average mass

N

N-terminus

The end of a peptide chain with the free amine group. Written on the left by convention.See: C-terminus Acetylation

Net peptide content

The share of the powder in a vial that is peptide, after salts and water. Often 70–90%. Purity and net peptide content are different measures.See: Purity Salt form

P

Peptide

A chain of amino acids joined by peptide bonds, usually up to about 50. Longer chains are called proteins.See: Peptide bond

Peptide bond

The link between one amino acid's carboxyl group and the next one's amine. It absorbs UV light at around 220 nm, which is how HPLC sees peptides.See: HPLC

Pharmacokinetics

How the body takes up, spreads, breaks down and clears a substance over time.See: Half-life

Placebo-controlled

A trial where one group gets an inactive dummy instead of the substance, so effects can be compared fairly.See: Clinical trial phases

PMID

PubMed ID: the number that identifies a paper in the US National Library of Medicine's database. Our references link to it.

Purity

In a certificate, the main peak's share of all peaks in an HPLC run. It says nothing about water or salt content.See: HPLC Net peptide content

R

Receptor

A protein on or in a cell that a molecule binds to, triggering a response.See: Agonist

Residue

One amino acid within a peptide chain, so called because it has lost water when the bond formed.See: Amino acid

Retention time

How long a substance takes to pass through the HPLC column. Each substance has its own under fixed conditions.See: Chromatogram

Reverse-phase

The usual form of HPLC for peptides. The column is water-repelling, so more water-repelling peptides stay longer.See: HPLC

S

S0

Class S0 of the WADA Prohibited List: any substance with no approval for human use by any government health authority. It is prohibited at all times.See: WADA Prohibited List

Salt form

The counter-ion a peptide is paired with, such as acetate or trifluoroacetate. It changes the weight of the powder, not the peptide.See: Acetate salt Trifluoroacetate

Sequence

The order of amino acids in a peptide, written from N-terminus to C-terminus in one- or three-letter codes.See: Residue

Solid-phase synthesis

How most peptides are made: built one amino acid at a time on tiny resin beads, then cut free and purified.

T

Trifluoroacetate

TFA. A salt form left over from synthesis and purification. Some suppliers exchange it for acetate.See: Salt form

W

WADA Prohibited List

The World Anti-Doping Agency's yearly list of substances and methods banned in sport. Each library entry gives the class, if any.See: S0