How to Use This Peptide Glossary
Entries in the peptide glossary run alphabetically and cover the terms used on Vinnix product pages, certificates of analysis and the Research Library. Where a fuller resource exists, the term links to it, so the peptide glossary also works as an index to the long-form articles. Compound entries stick to verified identity data.
Most terms in this peptide glossary belong to one of four groups: peptide chemistry (amino acid, peptide bond, sequence), analytical methods (HPLC, mass spectrometry, stationary phase), documentation (batch, lot number, COA) and individual compounds. If you want the longer story, start with what are peptides or the Research Library.
A
Amidation: Replacing the C-terminal carboxyl group with an amide, shown as -NH2 at the end of a sequence. The formula changes, and the mass drops by about 1 Da compared with the free acid.
Amino acid: An organic molecule with an amino group, a carboxyl group and a side chain, all attached to a central alpha carbon. Peptides and proteins are built from twenty standard amino acids. See also what are amino acids.
Amino-acid residue: An amino acid as it sits inside a peptide chain. Each peptide bond costs one water molecule, so a residue weighs about 18 Da less than the free amino acid. Expected peptide masses are calculated from residue masses.
Amino-acid sequence: The order of amino acids in a peptide or protein, written N-terminus to C-terminus in one-letter or three-letter code. It's the primary description of a peptide's identity.
Analytical chemistry: The branch of chemistry that identifies substances and measures how much of each is there. In peptide work, that means methods like HPLC, mass spectrometry and LC-MS used to characterize a sample.
B
Batch: Material made in one defined production run under the same conditions. A COA or any other analytical report applies only to the batch that was tested, identified by its batch or lot number.
BPC-157: A synthetic 15-amino-acid peptide (pentadecapeptide), sequence GEPPPGKPADDAGLV, molecular weight 1419.5 g/mol. Vinnix carries it in the catalog.
C
C-terminus: The end of a peptide chain with the free carboxyl group, or an amide if it has been modified. Sequences list it last.
CAS number: A unique numeric identifier the Chemical Abstracts Service registry assigns to a chemical substance. Handy for checking that two sources mean the same compound, though salts and modified forms can carry separate numbers.
Certificate of Analysis (COA): A document that reports specified analytical results, identity and purity for example, for one batch of material. It should name the product, batch number, methods, results and testing date. See how to read a COA.
Chirality: The property of a molecule that can't be superimposed on its mirror image. Every standard amino acid apart from glycine is chiral and comes in L and D forms. Proteins use L-amino acids.
Chromatogram: The plot chromatography produces, detector response against time. Each peak is a separated component, and peak area gives an estimate of how much of each is present relative to the others.
Chromatography: A family of separation techniques where a mixture's components move at different rates between a mobile phase and a stationary phase. For peptides, HPLC is the go-to form.
CJC-1295: A synthetic analogue of the first 29 residues of GHRH, with several substitutions. The versions with and without a drug affinity complex (DAC) are different molecules with different masses.
CJC-1295 + Ipamorelin: A Vinnix research blend that pairs CJC-1295 with ipamorelin. Component details and batch documentation are on the product page.
Compound: A distinct chemical substance with a defined composition and structure. Each Vinnix compound page records verified identity data: sequence, formula, molecular weight and registry numbers. Compound names in the peptide glossary link to those pages, or you can browse the full Compound Library.
Cyclic peptide: A peptide with part of its chain closed into a ring, through a lactam or disulfide bond for instance. PT-141 is one. Closing the ring releases water, so the mass changes.
D
D-amino acid: The mirror-image form of a chiral amino acid. Natural proteins rarely contain D-residues, but some synthetic peptides do, such as the D-arginine in SS-31. Mass is identical to the L-form.
Deamidation: A chemical change that turns an asparagine or glutamine side-chain amide into a carboxylic acid and adds about 1 Da. Analysts routinely watch for it in peptide samples. Moisture and temperature affect how fast it happens, which is one reason storage conditions get recorded.
Dipeptide: Two amino acids joined by a single peptide bond. You can't get a smaller peptide.
E
Electrospray ionization (ESI): A soft ionization method that converts molecules in solution into gas-phase ions for mass spectrometry. Peptides often pick up several protons and appear as multiply charged ions.
G
GHK-Cu: The copper complex of the tripeptide glycyl-histidyl-lysine (GHK), also called copper tripeptide-1, molecular weight 402.9 g/mol. One of the compounds in the Vinnix catalog.
GLOW Blend: A Vinnix research blend of GHK-Cu, TB-500 and BPC-157. Specifications and batch documentation live on the product page.
Glutathione: A tripeptide of glutamate, cysteine and glycine (gamma-Glu-Cys-Gly), molecular weight 307.3 g/mol. Its first bond runs through glutamate's side-chain gamma carboxyl instead of the usual alpha carboxyl.
H
HPLC: High-performance liquid chromatography, which pumps a sample through a packed column to separate its components. It's the standard way to estimate peptide purity. Compare HPLC vs mass spectrometry.
I
Identity: Confirmation that a sample is the compound it is labeled as, usually by matching its measured mass to the expected value. Identity and purity answer different questions, so a COA should report both.
In vitro / in vivo: Latin for "in glass" and "within the living". In vitro work happens outside an organism, in cultured cells, tissue or purified systems; in vivo work happens in a whole living organism. A research summary should say which kind of study produced each finding.
Ion: An atom or molecule with a net electric charge. Mass spectrometers can only measure ions, so peptides have to be ionized first, usually by adding protons.
Ipamorelin: A synthetic pentapeptide, Aib-His-D-2-Nal-D-Phe-Lys-NH2, molecular weight 711.9 g/mol. Several of its residues are non-standard, and it ends in a C-terminal amide.
K
KLOW Blend: A Vinnix multi-component research blend. Its component list and the amount of each component will be listed on the batch COA when published.
KPV: The tripeptide Lys-Pro-Val, matching residues 11 to 13 of alpha-melanocyte-stimulating hormone. Molecular weight 342.4 g/mol in the free-acid form.
L
LC-MS: Liquid chromatography coupled to mass spectrometry. The chromatograph separates the sample, then the mass spectrometer weighs each separated component, tying purity and identity data together.
Lot number: An identifier given to a specific production lot so a product can be traced back to its records. In practice it's often used interchangeably with batch number. Either way, the number on a COA should match the product label.
Lyophilization: Freeze-drying, or pulling water out of a frozen material under vacuum by sublimation. A lot of peptides ship as lyophilized powders, and the general principles for keeping them are covered under peptide storage.
M
Mass spectrometry: An analytical technique that measures the mass-to-charge ratio of ions. With peptides, its main job is confirming identity by comparing measured mass against the expected value.
Mass spectrum: What a mass spectrometer outputs: ion signal intensity plotted against mass-to-charge ratio. A peptide spectrum often shows a run of peaks for different charge states of the same molecule.
Mass-to-charge ratio (m/z): What a mass spectrometer actually measures, ion mass divided by charge number. Give a peptide three extra protons and it shows up at roughly a third of its mass.
Mobile phase: The liquid or gas that carries a sample through a chromatography column. Peptide HPLC usually runs a shifting mix of water and acetonitrile with a little acid.
Molecular formula: The count of atoms of each element in one molecule, C62H98N16O22 for BPC-157, say. It doesn't show how those atoms connect.
Molecular mass: The mass of a molecule, given either as average molecular weight in g/mol or as monoisotopic mass in daltons (Da). Mass spectrometry results get checked against these calculated values.
Molecular weight: The average mass of one molecule in g/mol, calculated from the molecular formula with standard atomic weights. It is the figure most product records list, 1419.5 g/mol for BPC-157 for example.
MOTS-c: A 16-amino-acid mitochondrial-derived peptide, sequence MRWQEMGYIFYPRKLR, molecular weight 2174.6 g/mol. Available in the Vinnix catalog.
N
N-terminus: The end of a peptide chain with the free amino group. Sequences list it first. It can be modified, for example by acetylation.
O
Oligopeptide: A peptide with only a few amino acids, commonly taken as about 2 to 20. There's no strict cutoff, and the term overlaps with dipeptide, tripeptide and short polypeptide, each of which has its own entry in the peptide glossary.
P
Peptide: Two or more amino acids joined by peptide bonds. The word names a broad class of molecules rather than one substance; peptides vary in sequence, length and structure. Most research peptides carry a code or short name; how peptides are named explains the conventions.
Peptide bond: The amide bond between the carboxyl group of one amino acid and the amino group of the next, formed with the loss of one water molecule. It's what links residues into a chain.
Peptide sequence: The exact order of amino acids in a particular peptide, modified residues and terminal groups included. Two peptides of the same length are different compounds if their sequences differ.
Polypeptide: A longer chain of amino acids joined by peptide bonds. Usage varies, but in this peptide glossary it means chains longer than oligopeptides. Proteins are made of one or more folded polypeptides.
PT-141: The development code for bremelanotide, a synthetic cyclic heptapeptide with a molecular weight of 1025.2 g/mol. Vinnix doesn't sell it; it has a Compound Library entry.
Purity: The share of a sample that is the target compound under a stated analytical method, usually reported from HPLC peak area. It isn't the same as peptide content, which also accounts for water and counter-ions. The longer explainer is peptide purity.
R
Retatrutide: An investigational peptide developed under the code LY3437943 and described as acting on the glucagon, GIP and GLP-1 receptors. It is not an approved medicine in the United States.
Retention time: How long a component takes to pass through a chromatography column to the detector. Under fixed conditions it's reproducible and helps identify peaks, but on its own it doesn't prove identity.
S
Selank + Semax: A Vinnix research blend of two synthetic heptapeptides. Selank is a tuftsin analogue; Semax is an analogue of the ACTH(4-10) fragment.
Semaglutide: A modified analogue of human GLP-1 with 31 backbone residues, an Aib substitution and a fatty-acid side chain. It is the active ingredient of approved prescription medicines; that approval does not cover research materials.
Sequence: In peptide chemistry, the ordered list of residues in a chain. People often use it as shorthand for amino-acid sequence or peptide sequence, and this peptide glossary does the same.
Sermorelin: A synthetic 29-residue peptide matching residues 1 to 29 of human GHRH, with a C-terminal amide and a molecular weight of 3357.9 g/mol. Listed as a Compound Library reference entry.
Solid-phase peptide synthesis (SPPS): The standard way to make synthetic peptides. The chain is built one protected amino acid at a time on an insoluble resin, then cleaved off and purified.
Spectrum: A plot of how a measured signal changes across a range, such as wavelength or mass-to-charge ratio. In peptide analysis it usually means a mass spectrum or a UV absorbance spectrum.
SS-31: A synthetic tetrapeptide, D-Arg-Dmt-Lys-Phe-NH2, also known as elamipretide, molecular weight 639.8 g/mol. It has a reference entry in the Compound Library.
Stationary phase: The fixed material inside a chromatography column that sample components interact with as the mobile phase flows by. Peptide HPLC typically uses silica particles bonded with C18 hydrocarbon chains.
T
TB-500: A name for synthetic material related to thymosin beta-4, a 43-amino-acid protein. Some products sold as TB-500 are the full sequence and some are short fragments, so the product record has to say which.
Tesamorelin: A synthetic peptide covering all 44 residues of human GHRH, capped with an N-terminal trans-3-hexenoyl group, molecular weight about 5136 g/mol. Vinnix stocks it in the catalog.
Tirzepatide: A 39-residue peptide-based compound, developed as LY3298176, described as acting on both the GIP and GLP-1 receptors. It is the active ingredient of approved prescription medicines; that approval does not cover research materials.
Tripeptide: Three amino acids joined by two peptide bonds. Glutathione, GHK and KPV all qualify, and each one has a separate entry in this peptide glossary.
W
Wolverine Blend: A Vinnix research blend of BPC-157 and TB-500. You'll find specifications and batch documentation on the product page.
Z
Zwitterion: A molecule that carries a positive and a negative charge at once. In water near neutral pH, free amino acids exist mostly as zwitterions.
FAQFrequently asked questions
What is the difference between a peptide, an oligopeptide and a polypeptide?
All three are chains of amino acids joined by peptide bonds. Oligopeptide usually means a short chain of roughly 2 to 20 residues, polypeptide a longer one, and peptide is the umbrella term for both. None of them has a strict, universal length cutoff, so usage shifts from one field to another. This peptide glossary follows the common ranges given above.
What is the difference between a batch number and a lot number?
Both tie material from a defined production run back to its records. Some organizations treat the terms as interchangeable; others use lot for a subdivision of a batch. In practice, the thing to check is that the number on the certificate of analysis matches the number on the product.
What is the difference between the stationary phase and the mobile phase?
The stationary phase is the fixed material packed inside the column. The mobile phase is the liquid flowing through it, carrying the sample. Components separate because each one interacts with the stationary phase to a different degree, so they exit the column at different retention times.
Is purity the same as identity?
No. Purity tells you how much of a sample is the target compound under a stated method, usually from HPLC peak area. Identity confirms that the main component is the right molecule, usually by mass spectrometry. A sample can be highly pure and still be the wrong compound, which is why you need both checks.
Why do some glossary entries link to compounds Vinnix does not sell?
Because readers run into these terms in the literature. The peptide glossary includes compounds from the Vinnix Compound Library that aren't in the catalog, such as sermorelin, SS-31 and PT-141. Their links go to reference pages that record verified identity data only and don't describe any product.