Glossary
Short, precise definitions of the terms you'll meet in peptide research and on our COAs.
A
- Aliquot
- A measured portion of a solution or sample, divided off so the remainder is not repeatedly opened or thawed.
- Amber Vial
- A glass vial tinted to block ultraviolet and short-wavelength visible light, protecting light-sensitive contents.
- Amino Acid Sequence
- The ordered list of amino acids in a peptide, written from the N-terminus to the C-terminus.
- Amylin
- A 37-residue pancreatic hormone co-secreted with insulin that slows gastric emptying and signals satiety.
- Angiogenesis
- The formation of new blood vessels from existing vasculature, regulated by growth factors such as VEGF.
- Animal Model
- A non-human species used to study biology or disease because it reproduces relevant features of human physiology.
- Apoptosis
- Programmed cell death: a regulated process by which cells dismantle themselves without provoking inflammation.
B
- Bacteriostatic Water
- Sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth in vials that are accessed repeatedly.
- BDNF (Brain-Derived Neurotrophic Factor)
- A neurotrophin that supports neuron survival, growth and synaptic plasticity, acting mainly through the TrkB receptor.
- Binding Affinity
- The strength of interaction between a ligand and its receptor, usually expressed as a dissociation constant (Kd or Ki).
- Bioavailability
- The fraction of an administered compound that reaches systemic circulation unchanged.
- Bioregulator Peptide
- A very short peptide, often 2–4 residues, proposed to regulate gene expression; mostly studied by Russian groups.
C
- C-Terminal Amidation
- Replacing a peptide's C-terminal carboxylic acid with an amide, a common natural and synthetic modification.
- Cell Culture
- Growing cells under controlled laboratory conditions outside the organism, a core in vitro research method.
- Cellular Senescence
- A state of stable growth arrest in which cells stop dividing but remain metabolically active and secrete signals.
- Certificate of Analysis (COA)
- A batch-specific document reporting the analytical test results that confirm a peptide's identity, purity and quality.
- Chromatogram
- The plot of detector signal against time produced by an HPLC run, used to calculate peptide purity.
- Clinical Trial Phases
- The staged sequence of human studies, from first-in-human safety testing to large confirmatory trials.
- Cold Chain
- An unbroken sequence of temperature-controlled storage and transport that keeps a product within a set range.
- Copper Peptide (GHK-Cu)
- The tripeptide glycyl-histidyl-lysine bound to copper(II), isolated from human plasma and studied in tissue remodelling.
- Counter-Ion
- An oppositely charged ion, such as acetate or trifluoroacetate, paired with charged groups in a peptide salt.
- Cyclic Peptide
- A peptide whose chain is closed into a ring through a backbone, side-chain or disulfide linkage.
D
- D-Amino Acid
- The mirror-image form of an amino acid; incorporating D-residues makes peptides resistant to many proteases.
- Dilute Acetic Acid
- A weak acid solution, often 0.1–1%, used to help dissolve basic or aggregation-prone peptides.
- Disulfide Bridge
- A covalent sulfur–sulfur bond between two cysteine residues that constrains a peptide's three-dimensional structure.
E
- EC50 (Half-Maximal Effective Concentration)
- The concentration of a compound producing 50% of its maximal response in a given assay; a measure of potency.
- Electrospray Ionization (ESI)
- A soft ionization method for mass spectrometry that produces multiply charged peptide ions from solution.
- Endotoxin
- Lipopolysaccharide from Gram-negative bacteria that can confound cell and animal studies; measured by the LAL test.
- Extracellular Matrix (ECM)
- The network of proteins and polysaccharides surrounding cells that provides structure and signalling cues.
F
G
- G Protein-Coupled Receptor (GPCR)
- A large family of seven-transmembrane receptors that signal through G proteins; the target of most peptide hormones.
- GH Secretagogue
- Any compound that stimulates the pituitary to release growth hormone, via the GHRH or ghrelin receptor.
- Ghrelin Receptor (GHS-R1a)
- The growth hormone secretagogue receptor type 1a, activated by ghrelin and by synthetic GHRPs such as Ipamorelin.
- GHRH (Growth Hormone-Releasing Hormone)
- A 44-residue hypothalamic peptide that stimulates growth hormone release via the pituitary GHRH receptor.
- GIP (Glucose-Dependent Insulinotropic Polypeptide)
- A 42-residue incretin hormone from intestinal K cells; its receptor is a target of dual and triple agonists.
- GLP-1 Receptor Agonist
- A compound that activates the glucagon-like peptide-1 receptor, the target of semaglutide and related incretin peptides.
- Glucagon Receptor (GCGR)
- The receptor for glucagon, regulating hepatic glucose output and lipid metabolism; a target of triple agonists.
H
- Half-Life
- The time required for a compound's concentration in a given system to fall by half.
- HPLC (High-Performance Liquid Chromatography)
- An analytical separation technique used to measure peptide purity by resolving the target from synthesis impurities.
- Hypothalamus
- A brain region linking the nervous and endocrine systems, producing releasing hormones that control the pituitary.
I
- IGF-1 (Insulin-Like Growth Factor 1)
- A 70-residue hormone produced mainly in the liver in response to growth hormone; a key mediator of GH signalling.
- In Vitro
- Research performed outside a living organism, such as in cell culture, tissue samples or purified-protein assays.
- In Vivo
- Research performed in a whole living organism, such as rodent models or human clinical trials.
- Incretin
- A gut hormone released after eating that amplifies glucose-dependent insulin secretion; mainly GLP-1 and GIP.
L
- LAL Assay
- The Limulus amebocyte lysate test, which detects bacterial endotoxin using a clotting cascade from horseshoe crab blood.
- Lipidation
- Attachment of a fatty-acid chain to a peptide, commonly to promote reversible binding to serum albumin.
- Lyophilization
- Freeze-drying: removing water from a frozen solution by sublimation under vacuum to stabilise a peptide as a dry powder.
M
- MALDI-TOF
- Matrix-assisted laser desorption/ionization with time-of-flight detection, a fast mass spectrometry method.
- Mass Spectrometry (MS)
- A technique that measures molecular mass to confirm a peptide's identity against its theoretical molecular weight.
- Melanocortin Receptor
- A family of five G protein-coupled receptors (MC1R–MC5R) regulating pigmentation, energy balance and more.
- Mitochondrial-Derived Peptide
- A short peptide encoded within mitochondrial DNA, such as humanin or MOTS-c, studied for metabolic signalling.
- Monoisotopic Mass
- A molecule's mass calculated using only the most abundant isotope of each element, such as carbon-12.
N
P
- Peer Review
- Evaluation of a research manuscript by independent experts before publication in a scholarly journal.
- PEGylation
- Covalent attachment of polyethylene glycol chains to a peptide to increase its size, solubility and circulation time.
- Peptide Bond
- The amide linkage joining the carboxyl group of one amino acid to the amino group of the next.
- Peptide Purity
- The proportion of peptide material in a sample that is the correct target sequence, usually measured by HPLC.
- Pharmacokinetics (PK)
- The study of how a compound is absorbed, distributed, metabolised and eliminated by an organism over time.
- Pituitary Gland
- A small endocrine gland at the base of the brain that releases growth hormone, ACTH, TSH and other hormones.
- Preclinical
- Research conducted before human trials, including in vitro studies and animal models.
R
- Randomized Controlled Trial (RCT)
- A study that randomly assigns participants to an intervention or control group to test cause and effect.
- Receptor Agonist
- A molecule that binds a receptor and activates it, producing a biological response.
- Receptor Antagonist
- A molecule that binds a receptor without activating it, blocking the action of agonists.
- Reconstitution
- Dissolving a lyophilised peptide in a chosen diluent to produce a solution of known concentration.
- Research Use Only (RUO)
- A label stating a product is supplied for laboratory research and is not intended for human or veterinary use.
- Residue
- A single amino acid unit within a peptide chain, after it has lost water in forming peptide bonds.
- Retention Time
- The time a compound takes to elute from an HPLC column, characteristic of it under fixed method conditions.
S
- Senolytic
- A compound that selectively induces death of senescent cells, studied as an approach in ageing research.
- Solid-Phase Peptide Synthesis (SPPS)
- The standard method for making synthetic peptides by adding protected amino acids one at a time to a resin-bound chain.
- Somatostatin
- An inhibitory peptide hormone that suppresses growth hormone, insulin, glucagon and many other secretions.
- Sterile Water
- Water that has been sterilised and contains no preservative, used as a diluent for single-use preparations.
- Sterility Testing
- Testing that checks a sample for viable microorganisms; distinct from endotoxin testing, which detects bacterial debris.
- Systematic Review
- A structured synthesis of all available studies on a defined question, using predefined search and selection methods.
T
- Telomerase
- A ribonucleoprotein enzyme that adds repeat sequences to chromosome ends, counteracting telomere shortening.
- TFA Salt
- A peptide carrying trifluoroacetate counter-ions left over from synthesis and HPLC purification.
- Thymosin
- A family of small proteins first isolated from the thymus, including thymosin alpha-1 and thymosin beta-4.