AmericanPeptide
Glossary

Peptide research glossary

Plain-language definitions for the terms that come up across the catalog, calculator, and research guides — from reconstitution and GRAVY to GLP-1, GHRH, and Certificates of Analysis. 118 terms across 5 categories.

Dosing & Preparation14

Peptide Chemistry26

Acylation

Attaching a fatty-acid chain to extend half-life via albumin binding.

Amino Acid

The building-block molecules of peptides and proteins.

C-Terminal Amidation

Replacing the C-terminal carboxyl with an amide — a common bioactivity-preserving modification.

C-Terminus

The free-carboxyl end of a peptide chain.

Cyclic Peptide

A peptide whose chain forms a ring, increasing stability and receptor selectivity.

D-Amino Acid

The mirror-image chirality of a standard amino acid — used to resist enzymatic degradation.

Dalton

Da

The unit of molecular mass.

Deletion Sequence

A synthesis impurity missing one or more residues from the target sequence.

Disulfide Bond

A covalent bond between two cysteine residues that stabilizes structure.

GRAVY

Grand Average of Hydropathy — a sequence’s mean hydrophobicity.

HPLC

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

Hydropathy

How water-attracting or water-repelling an amino acid is.

Isoelectric Point

pI

The pH at which a peptide carries no net charge.

Mass Spectrometry

MS

An analytical technique that confirms molecular identity by measuring mass.

Molecular Weight

MW

The mass of a molecule, expressed in daltons.

N-Terminal Acetylation

Capping the N-terminus with an acetyl group to improve stability.

N-Terminus

The free-amino end of a peptide chain.

PEGylation

Attaching polyethylene glycol chains to extend half-life and reduce immunogenicity.

Peptide

A short chain of amino acids linked by peptide bonds.

Peptide Bond

The amide bond linking one amino acid to the next.

Protecting Group

A temporary chemical block used in SPPS to prevent unwanted side reactions.

Residue

A single amino acid unit within a peptide chain.

Resin

The solid support to which the growing peptide chain is anchored during SPPS.

Sequence

The ordered list of amino acids in a peptide.

SPPS

Solid-phase peptide synthesis — the primary method for manufacturing research peptides.

TFA Salt

TFA

Trifluoroacetate counterion — a common byproduct of SPPS that appears in the final peptide.

Mechanisms & Biology48

Ac-SDKP

A tetrapeptide fragment of thymosin β4 with anti-inflammatory and anti-fibrotic activity.

Agonist

A molecule that binds and activates a receptor.

AMPK

AMP-activated protein kinase — the cell's central energy-sensing enzyme.

Angiogenesis

The formation of new blood vessels from existing ones.

Antimicrobial Peptide

AMP

A class of innate-immunity peptides that directly kill or disable pathogens.

Autophagy

The cell's recycling system — disposing of damaged proteins and organelles.

BDNF

Brain-derived neurotrophic factor, a target of cognition research.

Blood–Brain Barrier

BBB

The selective barrier between blood and brain tissue that restricts most peptides from entering the CNS.

cAMP

Cyclic AMP — the second messenger downstream of many GPCR-linked peptide receptors.

Cardiolipin

An inner-mitochondrial-membrane lipid essential for energy production.

Collagen

The most abundant structural protein — a primary target in wound healing research.

Cortisol

The primary stress glucocorticoid — relevant to GH-axis peptide research.

DPP-4

The enzyme that rapidly degrades incretins like GLP-1.

Epigenetic

Gene expression changes that don't alter the DNA sequence — methylation, acetylation, etc.

Fibroblast

The cell type responsible for synthesizing collagen and extracellular matrix.

Gastric Emptying

The rate at which the stomach empties its contents into the small intestine.

Ghrelin

The endogenous "hunger hormone" and natural ligand for the GHS-R1a receptor.

GHRH

Growth hormone-releasing hormone — the hypothalamic GH signal.

GHRP

Growth hormone-releasing peptides acting on the ghrelin receptor.

GHS-R1a

Growth hormone secretagogue receptor 1a — the target of GHRPs and ghrelin.

GIP

Glucose-dependent insulinotropic polypeptide, a second incretin.

GLP-1

Glucagon-like peptide-1, an incretin targeted for diabetes and weight loss.

Glucagon

The counter-regulatory hormone to insulin — raises blood glucose; targeted by triple agonists.

HPG Axis

HPG

The hypothalamic-pituitary-gonadal hormone feedback system.

IGF-1

Insulin-like growth factor 1, the downstream mediator of GH.

Immune Modulation

Adjusting immune activity up or down — not wholesale suppression.

Incretin

Gut hormones that boost insulin release after eating.

Insulin Resistance

Reduced cellular response to insulin — a driver of type 2 diabetes and metabolic syndrome.

Ketogenesis

The liver's production of ketone bodies from fatty acids during carbohydrate restriction.

Kisspeptin

The master upstream regulator of the reproductive hormone axis.

Lipid Metabolism

The biochemical processes by which fats are synthesized, stored, and broken down.

Melanocortin

A receptor/peptide family regulating pigmentation, energy, and sexual function.

mTOR

A kinase that integrates nutrient signals and regulates cell growth and aging.

NAD+

A coenzyme central to energy metabolism that declines with age.

Neuropeptide

A peptide that acts as a signaling molecule in the nervous system.

NF-κB

A master transcription factor controlling inflammatory gene expression.

Nitric Oxide

NO

A gaseous signaling molecule mediating vasodilation and tissue repair.

Oxidative Stress

Cellular damage from excess reactive oxygen species — a driver of aging.

Prolactin

A pituitary hormone that some GH secretagogues elevate as a side effect.

Pulsatile Release

The natural pattern of growth hormone secretion — bursts followed by troughs.

Receptor

A protein that binds a signaling molecule and initiates a cellular response.

Secretagogue

A substance that triggers secretion of a hormone.

Senolytic

An agent that clears senescent “zombie” cells.

Synaptic Plasticity

The ability of synapses to strengthen or weaken in response to activity — the basis of learning.

Telomere

Protective caps on chromosomes that shorten with each cell division — a marker of biological aging.

Toll-Like Receptor

TLR

Pattern-recognition receptors of innate immunity that detect microbial motifs.

VEGF

Vascular endothelial growth factor — the primary driver of new blood vessel formation.

α-MSH

Alpha-melanocyte-stimulating hormone — the master endogenous melanocortin peptide.

Identifiers & Standards10

Research & Regulatory20

Adverse Event

AE

Any undesirable experience occurring in a trial participant — reported and graded.

Binding Affinity

Ki / EC₅₀

A measure of how tightly a compound binds to or activates its receptor target.

Biomarker

A measurable biological indicator used to track disease or treatment response.

Clinical Phase

The staged structure of human clinical trials (Phase 1–4).

Dose-Response Relationship

How the magnitude of an effect changes with increasing dose.

Double-Blind

Neither participants nor investigators know who received treatment — the strongest bias control.

Endpoint

The outcome measured in a clinical trial to assess treatment effect.

FDA Approved

Cleared by the U.S. FDA as safe and effective for a specific use.

HSDD

Hypoactive sexual desire disorder, a melanocortin-peptide endpoint.

In Vitro

in vitro

Research performed in cell cultures or isolated tissues outside a living organism.

In Vivo

in vivo

Research performed in living organisms — animal models or humans.

MASH

A liver disease studied as a metabolic-peptide endpoint.

Off-Label Use

Prescribing an approved drug outside its approved indication.

Peer-Reviewed

Research evaluated by independent scientific experts before publication.

Pharmacodynamics

PD

What a drug does to the body — receptor binding, downstream effects, dose-response.

Pharmacokinetics

PK

How the body absorbs, distributes, metabolizes, and excretes a drug — ADME.

Placebo

An inert comparator used in controlled trials to isolate treatment effects.

Preclinical

Studies conducted before human trials — cell, tissue, and animal models.

Randomized Controlled Trial

RCT

The gold-standard trial design — participants randomly assigned to treatment or control.

Systematic Review

A structured synthesis of all eligible studies on a research question.

Research use only. Definitions are educational references, not medical advice or dosing guidance. Independent validation required for any experimental use.

Looking for compounds instead of definitions?

Browse the catalog