Peptide Glossary

The fundamental building blocks of peptides and proteins. There are 20 standard amino acids, each with a unique side chain that determines its chemical properties. When amino acids are joined in a specific sequence by peptide bonds, they form a peptide. The sequence and length of the chain determine the peptide's biological activity.

Sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth. BAC water is the standard diluent for reconstituting lyophilised peptides because the preservative allows the reconstituted solution to be stored for up to 28 days when refrigerated. Plain sterile water should be used immediately after reconstitution; BAC water extends usable life considerably.

The proportion of a compound that reaches systemic circulation in an active form. Oral bioavailability of most peptides is very low because digestive enzymes break them down before absorption. Subcutaneous or intramuscular administration bypasses the digestive system, delivering the peptide directly into tissue where it can be absorbed into the bloodstream.

A document issued by an independent laboratory confirming the identity, purity, and potency of a peptide batch. A CoA typically includes the HPLC chromatogram, mass spectrometry (MS) confirmation of molecular weight, and the lot number. Helixa publishes CoAs for every batch on the Certificates page so researchers can verify what they receive.

A class of synthetic peptides that stimulate the pituitary gland to release growth hormone by binding to the ghrelin receptor. GHRPs work synergistically with GHRHs (Growth Hormone Releasing Hormones) to produce a more pronounced GH pulse. Examples include GHRP-2 and GHRP-6. They are commonly studied for their roles in body composition, recovery, and metabolic research.

A class of peptides that stimulate the pituitary to produce and release growth hormone by binding to the GHRH receptor. Unlike GHRPs, which act via the ghrelin receptor, GHRHs act through a distinct pathway. When combined with a GHRP, the two classes produce a synergistic effect on GH release. CJC-1295 and Sermorelin are well-known GHRH analogues.

An analytical technique used to separate, identify, and quantify each component in a peptide sample. A solution is forced through a column packed with absorbent material under high pressure; different compounds travel through at different rates, producing a chromatogram. HPLC is the gold standard for verifying peptide purity — a result of ≥99% means less than 1% of the sample is anything other than the target peptide.

The time it takes for the concentration of a compound in the body to reduce by half. Peptides generally have short half-lives due to enzymatic degradation by proteases. Modifications such as PEGylation, cyclisation, or the addition of fatty acid chains (acylation) can extend half-life significantly. Understanding half-life is important for determining dosing frequency in research protocols.

Injection directly into muscle tissue. Intramuscular administration typically results in faster absorption than subcutaneous injection due to the higher vascularity of muscle. It is used for compounds that require rapid onset or that are not well-absorbed via the subcutaneous route.

A preservation process that removes water from a peptide by first freezing it, then reducing the surrounding pressure so the ice sublimates directly to vapour. The result is a stable, dry powder that retains full biological activity and has a significantly longer shelf life than liquid formulations. Helixa supplies all peptides in lyophilised form.

An analytical method that measures the mass-to-charge ratio of ionised molecules. For peptides, MS confirms the molecular weight of the compound, providing definitive identity verification that complements HPLC purity data. A match between the measured and theoretical molecular weight confirms the correct peptide sequence was synthesised.

A measure of how much of a peptide sample is the intended compound versus impurities such as truncated sequences, oxidised residues, or synthesis by-products. Expressed as a percentage, with ≥98% considered research-grade and ≥99% considered pharmaceutical-grade. Helixa targets ≥99% purity across its range, verified by third-party HPLC analysis.

A short chain of amino acids linked by peptide bonds, typically fewer than 50 residues. Peptides are naturally occurring signalling molecules in the body — they regulate processes including growth hormone release, immune function, tissue repair, and metabolism. Synthetic research peptides are designed to mimic or modulate these natural signals.

The covalent chemical bond formed between the carboxyl group of one amino acid and the amino group of another, releasing a water molecule in the process (condensation reaction). Peptide bonds are the structural backbone of all peptides and proteins. They are relatively stable under physiological conditions but can be cleaved by enzymes called proteases.

The process of attaching polyethylene glycol (PEG) chains to a peptide molecule. PEGylation increases the hydrodynamic size of the peptide, reducing kidney filtration and enzymatic degradation, which significantly extends its half-life in circulation. CJC-1295 with DAC (Drug Affinity Complex) is an example of a modified peptide with extended duration of action.

The enzymatic breakdown of proteins and peptides by proteases. In vivo, proteolysis is the primary reason most peptides have short half-lives — enzymes in the blood and tissues rapidly cleave peptide bonds. Researchers use various strategies to resist proteolysis, including D-amino acid substitution, cyclisation, and chemical modifications like PEGylation.

The process of dissolving a lyophilised peptide powder back into a liquid solution, typically using BAC water or sterile water. The diluent is injected slowly down the side of the vial — never directly onto the powder — and the vial is gently swirled (not shaken) to avoid denaturing the peptide. The resulting solution should be clear; cloudiness may indicate degradation or incorrect technique.

Any substance that causes another substance to be secreted. In the context of peptide research, growth hormone secretagogues (GHS) are compounds that stimulate the release of growth hormone from the pituitary gland. Both GHRPs and GHRHs are classified as GH secretagogues, though they act through different receptor pathways.

Referring to the layer of tissue directly beneath the skin (hypodermis). Subcutaneous injection delivers a compound into this fatty tissue layer using a short, fine needle. It is one of the most common administration routes for research peptides because it allows for slow, consistent absorption into the bloodstream and is generally well-tolerated.

The standard method for manufacturing synthetic peptides. Amino acids are added one at a time to a growing chain anchored to a solid resin support. After the full sequence is assembled, the peptide is cleaved from the resin and purified. SPPS allows precise control over sequence and enables the incorporation of non-natural amino acids and chemical modifications.