This glossary defines terminology used across the PepperCo Research Hub. Terms are grouped alphabetically; use the navigation bar to jump to any letter. All definitions describe laboratory and in vitro research contexts only.

A

Acetonitrile

A common organic solvent widely used as the mobile phase in reverse-phase HPLC separation of peptides and other research materials. Its low viscosity and strong elution strength make it a standard choice for analytical chromatography.

Amide Bond

Also called a peptide bond; the covalent bond linking the carboxyl group of one amino acid to the amino group of another. The amide bond is the fundamental linkage that defines a peptide chain.

Amino Acid

The building block of peptides and proteins. Twenty standard amino acids are encoded by the genetic code, each distinguished by its side chain. A peptide’s identity and behavior are determined by its amino acid sequence.

Analytical Grade

A purity standard indicating a reagent is suitable for analytical laboratory procedures. Analytical-grade materials meet defined specifications for identity and impurity limits, supporting reproducible test results.

API (Active Principal Ingredient)

The biologically active component in a formulated product. In research contexts, the peptide itself is the active component under study. The term is used here to describe the identity of a research material, not to imply any formulated, diagnostic, or therapeutic application.

B

Bacteriostatic Water

Water containing 0.9% benzyl alcohol, used for reconstituting lyophilized peptides in laboratory settings. The benzyl alcohol component inhibits microbial growth in the reconstituted reagent over short-term laboratory use.

Batch Number

A unique identifier assigned to a specific production run, used for traceability in quality documentation. The batch number links a vial of reagent to its corresponding Certificate of Analysis and manufacturing records.

BDNF

Brain-Derived Neurotrophic Factor, a protein studied in neuroscience research for its role in neuronal growth and maintenance. BDNF is widely investigated in cell-culture and animal research models of neural plasticity.

C

CAS Number

A unique numerical identifier assigned to a specific compound by an internationally recognized abstracting registry. CAS numbers provide an unambiguous reference for identifying a research material across scientific literature and supply documentation.

C18 Column

A type of reverse-phase HPLC column commonly used for peptide separation and analysis. The C18 designation refers to the eighteen-carbon chain bonded to the silica stationary phase, which provides strong hydrophobic retention.

Certificate of Analysis (COA)

A document issued by a testing laboratory verifying the identity, purity, and quality of a specific batch of reagent. A COA reports the analytical results — such as HPLC purity and mass spectrometry confirmation — for the batch it accompanies. See What Is a Certificate of Analysis (COA)?

Chromatogram

The visual output of a chromatography run, showing separated components as peaks over time. Each peak represents a distinct compound eluting from the column; peak area is used to estimate relative concentration in purity analysis.

Copper Peptide

A peptide that binds copper ions, such as GHK-Cu, studied for tissue remodeling research. Copper-binding peptides are investigated in cell-culture and animal models for their interactions with extracellular matrix components. See What Is GHK-Cu?

C-Terminus

The end of a peptide chain with a free carboxyl group. By convention, peptide sequences are written from the N-terminus to the C-terminus, reflecting the direction of synthesis and reading.

D

Dipeptide

A peptide consisting of two amino acids joined by a single peptide bond. Dipeptides are the shortest peptide structures and are commonly studied as models of bond formation and metabolic processing.

Disulfide Bond

A covalent bond between two sulfur atoms, important for three-dimensional peptide structure. Disulfide bonds form between cysteine residues and help stabilize the folded conformation of many peptides and proteins.

E

Elution

The process of washing a substance through and out of a chromatography column. In HPLC, elution is driven by the mobile phase, and the conditions of elution determine how effectively a peptide is separated from impurities.

Epimer

A stereoisomer that differs at one chiral center. In peptide research, epimers can arise during synthesis and are tracked as potential impurities because they may behave differently in analytical and biological assays.

Extracellular Matrix (ECM)

The non-cellular component of tissue that provides structural support and a scaffold for molecular interactions, studied in connective tissue response research. Several research peptides are investigated for their interactions with ECM components in laboratory models.

F

Fluorenylmethyloxycarbonyl (Fmoc)

A protecting group used in solid-phase peptide synthesis. The Fmoc group shields the amino terminus of a growing peptide chain and is removed under basic conditions to allow the next coupling step.

Fragment

A shorter peptide chain produced by enzymatic or other cleavage of a longer peptide. Fragments are characterized during peptide mapping to confirm the identity and sequence of the parent compound.

Freeze-Drying

See Lyophilization. The terms are used interchangeably in peptide research to describe the sublimation-based drying process used to preserve reagents. See What Is Lyophilization?

G

GHS (Growth Hormone Secretagogue)

A compound that stimulates growth hormone release, studied in endocrine research. GHS-class research peptides are investigated in laboratory models for their interactions with the ghrelin receptor and related signaling pathways.

Glutathione (GSH)

A tripeptide (γ-Glu-Cys-Gly) that serves as a major intracellular antioxidant. Glutathione is one of the most studied research materials in oxidative-stress research. See What Is Glutathione?

Gradient Elution

An HPLC technique where the mobile phase composition changes over time to improve separation. A gradient typically increases the proportion of organic solvent, eluting peptides in order of increasing hydrophobicity.

H

HPLC (High-Performance Liquid Chromatography)

An analytical technique for separating, identifying, and quantifying components in a mixture — the gold standard for peptide purity testing. HPLC separates compounds based on their differential interaction with a stationary phase and a flowing mobile phase. See What Is HPLC Testing?

Hydrophilic

Having an affinity for water; a property relevant to peptide solubility. Hydrophilic amino acid residues tend to be exposed to solvent and influence how readily a peptide dissolves in aqueous reconstitution.

Hydrophobic

Repelling water; a property that affects peptide behavior in chromatography. Hydrophobic residues interact strongly with reverse-phase stationary phases, which is the basis of their separation in HPLC.

I

In Vitro

Refers to studies performed outside of a living organism, typically in test tubes or cell cultures. All PepperCo Research materials are supplied for in vitro and laboratory research applications.

In Vivo

Refers to studies performed in living organisms. The distinction between in vitro and in vivo research is fundamental to interpreting published data on any research material.

Isoelectric Point (pI)

The pH at which a peptide has no net electrical charge. At its pI, a peptide’s solubility is typically at a minimum, which is relevant to reconstitution, storage, and chromatographic behavior.

K

Kinetic Stability

The rate at which a peptide degrades under defined storage conditions, relevant to reagent handling. Kinetic stability data inform recommended storage temperature, light protection, and reconstitution practices for a given research material.

L

Limit of Detection (LOD)

The lowest concentration of an analyte that can be reliably detected by an analytical method. The LOD is distinct from the limit of quantification and is reported on methods used for impurity screening.

Lyophilization

A freeze-drying process that removes water from a substance by sublimation, used to preserve peptide reagents. Lyophilization extends shelf life and maintains integrity during shipping. See What Is Lyophilization?

Lyophilized

The state of a substance that has been freeze-dried; research peptides are commonly supplied as lyophilized powder. A lyophilized reagent is reconstituted in a suitable solvent immediately before laboratory use.

M

Mass Spectrometry (MS)

An analytical technique that measures the mass-to-charge ratio of ions, used to confirm peptide identity and molecular weight. MS is typically paired with HPLC to verify that a research material matches its expected mass.

Melanocortin

A family of peptides including α-MSH, studied in inflammation and pigmentation research. Melanocortin-system research peptides are investigated in cellular and animal models for their receptor interactions.

Mobile Phase

The liquid that carries the sample through an HPLC column. In reverse-phase HPLC, the mobile phase is a blend of water and an organic solvent whose composition determines elution strength.

Molecular Weight

The mass of a molecule, typically expressed in Daltons or g/mol. Molecular weight is a primary identity check for peptides and is confirmed by mass spectrometry on a batch’s Certificate of Analysis.

N

N-Terminus

The end of a peptide chain with a free amino group. Peptide sequences are written and synthesized starting from the N-terminus, and many analytical strategies distinguish peptides by their N-terminal characteristics.

Ninhydrin

A reagent used to detect amino acids and peptides in chromatography. Ninhydrin reacts with primary amines to produce a visible color, making it useful for visualizing separated components on certain media.

O

Oligopeptide

A short peptide chain, typically 2-20 amino acids. Most research peptides supplied as lyophilized reagents fall within the oligopeptide range. See What Are Peptides?

Oxidation

A reaction involving the loss of electrons; relevant to peptide stability and glutathione research. Oxidation can modify cysteine and methionine residues, and tracking oxidative modification is a common analytical objective.

P

Peptide Bond

The amide bond linking two amino acids in a peptide chain. Each peptide bond forms through the condensation of a carboxyl group and an amino group, releasing a molecule of water.

Peptide Mapping

An analytical strategy for identifying peptides by their characteristic fragments. Peptide mapping digests a peptide or protein into defined fragments that are then separated and matched to an expected profile.

Peptide Synthesis

The process of creating peptides, typically via solid-phase peptide synthesis (SPPS). Synthetic production allows researchers to obtain peptides with defined sequences and controlled purity for laboratory study.

Pentapeptide

A peptide consisting of five amino acids. Pentapeptides are common in research catalogs and are studied across a range of laboratory models.

pH

A measure of hydrogen ion concentration; important for peptide solubility and stability. The pH of a reconstitution solvent influences how a peptide dissolves and how long it remains intact in solution.

Polypeptide

A longer peptide chain, typically more than 20 amino acids but shorter than a full protein. The boundary between a polypeptide and a protein is not strictly defined and is often used loosely in research literature.

Purity

The percentage of the target peptide relative to total content, typically measured by HPLC. Research-grade peptides should be ≥99%. Purity is reported on a batch’s Certificate of Analysis.

R

Reagent

A substance used in laboratory research and analysis; PepperCo products are research reagents. The term distinguishes a material intended for laboratory use from a formulated or finished product.

Reconstitution

The process of dissolving a lyophilized peptide in a suitable solvent for laboratory use. The choice of solvent — such as bacteriostatic water or an aqueous buffer — depends on the peptide’s solubility and the intended assay.

Research Use Only (RUO)

A designation indicating a product is intended for research purposes only, not for diagnostic or therapeutic use. All PepperCo Research materials are supplied under an RUO designation for in vitro and laboratory applications.

Retention Time

The time it takes a compound to pass through an HPLC column, used for identification. Under fixed conditions, a peptide’s retention time is reproducible and can be matched against a reference standard.

Reverse-Phase HPLC

A common HPLC mode where the stationary phase is hydrophobic and the mobile phase is hydrophilic. Reverse-phase separation is the most widely used approach for peptide purity analysis. See What Is HPLC Testing?

S

Sequence

The ordered list of amino acids that make up a peptide. The sequence fully defines a linear peptide’s identity and is the primary specification reported on its Certificate of Analysis.

Solid-Phase Peptide Synthesis (SPPS)

The most common method for synthesizing peptides in the laboratory. SPPS builds a peptide stepwise on an insoluble resin support, allowing excess reagents to be removed by washing between coupling cycles.

Stationary Phase

The solid material inside an HPLC column that separates components. The stationary phase’s properties — such as the C18 bonded phase — determine how different peptides are retained and eluted.

Sterile

Free from living microorganisms; PepperCo peptide vials are supplied sterile. Sterility is verified through defined testing methods and supports reliable handling in laboratory research.

Sublimation

The transition of a substance from solid to gas without passing through a liquid phase, the basis of lyophilization. Sublimation under reduced pressure is what removes water from a frozen peptide while preserving its structure.

T

Tetrapeptide

A peptide consisting of four amino acids. Tetrapeptides are studied in a range of laboratory models and are common entries in research catalogs.

Third-Party Testing

Quality verification performed by an independent laboratory separate from the manufacturer. Third-party testing is used to corroborate a manufacturer’s reported purity and identity results. See What Is Third-Party Testing?

Tripeptide

A peptide consisting of three amino acids. Glutathione and several other well-studied research materials are tripeptides.

Truncation

An incomplete peptide sequence resulting from synthesis errors, a common impurity. Truncated sequences are shorter than the target peptide and are identified and quantified during HPLC purity analysis.

V

Vial

A small container used to store lyophilized peptide reagents; PepperCo products are supplied in sterile vials. Vials are sealed to maintain sterility and protect the lyophilized material until reconstitution.