Glossary

Amino acid

The building block of peptides and proteins. Twenty are standard. Many research peptides also use non-standard ones.

Residue

An amino acid unit within a chain. A 15-residue peptide has 15 amino acids.

Sequence

The order of residues from N-terminus to C-terminus. It defines the peptide's identity.

N-terminus / C-terminus

The start (free amino group) and the end (free carboxyl group) of a chain. "-NH2" at the end of a sequence means the C-terminus is amidated.

Aib

α-Aminoisobutyric acid, a non-standard residue used to resist enzymatic cleavage.

D-amino acid

The mirror-image form of an amino acid. Written with a "D-" prefix, as in D-Phe.

Lyophilisation

Freeze-drying: removing water from a frozen solution under vacuum.

HPLC

High-performance liquid chromatography. It separates the components of a sample, and is used to measure purity.

Mass spectrometry (MS)

Measures molecular mass, and is used to confirm identity.

Chromatogram

The HPLC trace: signal against time, with one peak per separated component.

HPLC purity

The main peak's share of total peak area. It is not the same as net peptide content.

Net peptide content

The share of the powder's weight that is peptide, as opposed to water and counter-ions.

Counter-ion

An ion such as acetate or trifluoroacetate (TFA) that pairs with charged groups on the peptide.

Lot (batch)

Material made and tested together. Each lot has its own certificate.

COA

Certificate of analysis: the laboratory's report for one lot.

COA pending

Our label for a lot whose certificate is not yet published.

Blend

A vial containing more than one compound. Blends are verified for identity and quantity, not given a single purity figure.

Research use only (RUO)

Sold for laboratory research. Not for human or veterinary use.

For laboratory research use only. This article describes chemistry and handling. It does not describe human use.