Plain-English definitions.

A short chain of amino acids — typically 2 to ~50 — joined by peptide bonds.

The ordered list of amino acids in a peptide, written N-terminus to C-terminus.

The 3D fold of a single peptide chain — how it arranges in space.

A covalent S-S bond between two cysteine residues — stabilises peptide / protein structure.

A peptide covalently attached to a fatty acid chain — extends half-life via albumin binding.

Freeze-dried — water removed by sublimation under vacuum.

Dissolving a lyophilised peptide back into solution before use.

Sterile water containing 0.9% benzyl alcohol as a bacteriostatic preservative.

High-performance liquid chromatography — the standard purity assay for research peptides.

Document showing the analytical results — typically purity, mass, and identity — for a specific batch of research peptide.

Identifies a compound by measuring its mass-to-charge ratio.

A calculated index of insulin resistance from fasting glucose × fasting insulin.

Glycated haemoglobin — average blood glucose over the past 8–12 weeks.

A unique numeric identifier assigned by Chemical Abstracts Service to every chemical substance.

The US National Library of Medicine's database of biomedical literature citations.

Digital Object Identifier — a permanent unique identifier for an academic paper or other published artefact.

The US registry of publicly and privately funded clinical studies.

Protein Data Bank identifier — a four-character code for a specific 3D protein structure.

Glucagon-like peptide-1, an incretin hormone that regulates glucose and appetite.

Glucose-dependent insulinotropic polypeptide, an incretin hormone with metabolic and adipose effects.

Growth hormone-releasing hormone, the hypothalamic peptide that triggers GH release.

Insulin-like growth factor 1 — the main downstream mediator of growth hormone effects.

Mechanistic target of rapamycin — a master regulator of cell growth, metabolism, and autophagy.

The cell's recycling process — sequestering and degrading damaged proteins and organelles.

Sex hormone-binding globulin — the liver-produced carrier of testosterone and oestradiol in blood.

Apolipoprotein B — a count of atherogenic lipoprotein particles, increasingly preferred over LDL-C for cardiovascular risk.

Methylenetetrahydrofolate reductase — enzyme that activates folate; common variants reduce its efficiency.

A pancreatic hormone co-secreted with insulin that slows gastric emptying and produces satiety.

The growth-hormone secretagogue receptor — also called the ghrelin receptor.

A pancreatic hormone that opposes insulin — raises blood glucose, promotes lipolysis and ketogenesis.

The enzyme that converts androgens to oestrogens.

Gut-derived hormones (GLP-1, GIP) that stimulate post-meal insulin secretion.

A unique phospholipid in the inner mitochondrial membrane essential for electron transport chain function.

A family of NAD+-dependent deacetylase enzymes implicated in longevity and metabolic regulation.

A cellular energy sensor — activated when ATP drops, promotes catabolic / energy-restoring pathways.

The biologically active 29-amino-acid N-terminal fragment of growth hormone-releasing hormone.

The penultimate stage of clinical drug development — large randomised trials testing efficacy and safety against existing standards of care.

How the body absorbs, distributes, metabolises, and eliminates a compound — "what the body does to the drug."

"What the drug does to the body" — the relationship between concentration and effect.

Three injection routes — intravenous, intramuscular, subcutaneous — with different absorption profiles.

The time required for plasma concentration of a compound to fall to half its initial value.

Authorisation by the US Food and Drug Administration to market a drug for a specific indication.

European Medicines Agency / UK Medicines and Healthcare Regulatory Agency — the EU and UK equivalents of the FDA.