21+ · VERIFIED LAB USE
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Plain definitions of the terms used on research peptide certificates, product pages and bench protocols - from acetate salt to lyophilization to tabular purity.
Acetate salt - the counterion form most research peptides are supplied in. It contributes to gross vial mass but is not counted in the stated net peptide mass.
Amidation - a C-terminal modification replacing the free acid with an amide. It is present in many native sequences and is often essential to receptor activity.
Bacteriostatic water - sterile water containing 0.9% benzyl alcohol as a preservative, used where a reconstituted solution needs to be held rather than used immediately.
CAS number - the Chemical Abstracts Service registry identifier, a unique key for a specific chemical substance.
Deletion sequence - a synthesis impurity missing one or more residues, caused by a failed coupling step.
Endotoxin - bacterial lipopolysaccharide, measured by LAL assay and reported in EU/mg.
Free acid - an unmodified C-terminal carboxyl group, as opposed to an amide.
Gamma-peptide bond - a linkage through a side-chain carboxyl rather than the alpha-carboxyl. Glutathione is the common example.
HPLC - high-performance liquid chromatography, the standard method for measuring peptide purity.
Hygroscopic - readily absorbing atmospheric moisture. Hygroscopic material must reach room temperature before the vial is opened.
Lactam bridge - a covalent link between two side chains that closes a peptide into a ring.
Lyophilization - freeze-drying under vacuum, which removes water and leaves a stable porous cake.
Molecular weight - the mass of one mole of the compound, used to convert between mass and molar concentration.
Non-standard residue - an amino acid outside the twenty proteinogenic set, such as Aib or D-2-naphthylalanine, usually included to resist enzymatic degradation.
Purity - the main peak's share of total peak area on the HPLC trace, expressed as a percentage.
Racemisation - inversion of stereochemistry at a chiral centre during synthesis, producing a diastereomer impurity.
Reconstitution - dissolving a lyophilized cake in a diluent to produce a working solution.
Sequence - the order of amino acid residues, conventionally written N-terminus to C-terminus.
U-100 graduation - an insulin syringe scale where 100 units correspond to 1.0 mL, commonly used for measuring small volumes at the bench.
This guide is general laboratory reference material relating to the handling of research compounds. It is not medical, veterinary or clinical guidance, and it does not describe or imply any use in humans or animals. All PeptideSeed material is supplied for in-vitro laboratory research only — see the terms of supply.