Glossary

Peptide research glossary

Concise explanations of 36 terms — what a peptide is, how a receptor works, what HPLC purity means, how semaglutide is regulated in Bulgaria. The goal of this page is to make our product descriptions understandable for everyone.

Basics

Peptide: Peptides are short chains of amino acids linked by peptide bonds. They are smaller than proteins and act as crucial signaling molecules in biological systems.
Amino acid: Amino acids are the fundamental building blocks of peptides and proteins. Hundreds exist in nature, but only 20 are standardly encoded in the genetic code of living organisms.
Receptor: A receptor is a specialized protein structure located on the surface or inside a cell. It recognizes and binds to specific molecules to trigger a particular cellular response.
Agonist: An agonist is a molecule that binds to a receptor and activates it. This triggers a biological response similar to that of a naturally occurring substance in the body.
Antagonist: An antagonist is a substance that attaches to a receptor but does not activate it. Instead, it blocks access to other molecules and stops their action.
Ligand: A ligand is any molecule that forms a complex with a biomolecule, usually a receptor, to transmit a signal. Peptides often function as ligands in the endocrine system.
Signal transduction: Signal transduction is the process by which a cell converts one kind of signal or stimulus into another. This typically involves a cascade of biochemical reactions after a ligand binds to a receptor.

Signalling systems

GLP-1 (Glucagon-Like Peptide-1): GLP-1 is an incretin hormone that stimulates insulin secretion in response to meals. Various synthetic analogs of this peptide are heavily researched and hold FDA and EMA approved status for specific metabolic conditions.
GIP (Glucose-dependent Insulinotropic Polypeptide): GIP is another key incretin hormone that works synergistically with GLP-1 to regulate glucose metabolism. In modern science, dual agonists are being developed to activate the receptors of both peptides simultaneously.
GHRH (Growth Hormone Releasing Hormone): GHRH is a hormone synthesized in the hypothalamus that stimulates the pituitary gland to produce and release growth hormone. Research peptides in this class mimic its action to study endocrine regulation.
GHRP (Growth Hormone Releasing Peptide): GHRPs are a group of synthetic peptides that stimulate the release of growth hormone by binding to the ghrelin receptor. They are used in laboratory settings to investigate the mechanisms of cellular growth and metabolism.
Melanocortin system (MC3R/MC4R): The melanocortin system is a complex network of peptides and receptors (like MC3R and MC4R) that regulate pigmentation, energy homeostasis, and inflammation. It is a frequent subject of research in neurobiology.
Kisspeptin: Kisspeptin is a neuropeptide that plays a fundamental role in initiating puberty and regulating the reproductive axis. It stimulates the release of gonadotropin-releasing hormone (GnRH).
Thymosin: Thymosins are small proteins originally isolated from the thymus gland that participate in immune response and tissue repair. In research practice, their potential to modulate cellular migration is studied.

Pharmacokinetics

Half-life: Half-life is the time required for the concentration of a substance in the body to decrease by half. This metric is crucial for determining dosing frequency in research settings.
Pharmacokinetics (PK): Pharmacokinetics studies what the body does to a substance from the moment of its introduction. It covers the processes of absorption, distribution, metabolism, and excretion.
Pharmacodynamics (PD): Pharmacodynamics investigates what a substance does to the body. It describes the biochemical and physiological effects of molecules and their mechanisms of action.
Bioavailability: Bioavailability is the fraction of an administered dose of a substance that reaches the systemic circulation unchanged. Intravenous administration offers 100% bioavailability, while other methods vary.
Clearance: Clearance is a measure of the rate at which the body eliminates a substance from blood plasma. It depends primarily on liver and kidney function.

Research methods

In vitro: In vitro studies are performed outside a living organism, usually in isolated cells or biological molecules in a laboratory setting. They are the first step in studying new peptides.
In vivo: In vivo studies are conducted on whole, living organisms, such as animals or humans. They provide insight into the systemic effect of a molecule in a complex biological environment.
Preclinical study: Preclinical studies are the research stage prior to human testing. They involve in vitro and in vivo experiments to assess the safety and biological activity of a compound.
Phase 1/2/3 clinical trial: Clinical trials go through several phases (1, 2, and 3) to evaluate the safety, efficacy, and optimal dosing of a new drug in humans. Successful completion of all phases is mandatory for regulatory approval.
Randomised controlled trial (RCT): A randomised controlled trial is the gold standard in science. Participants are randomly assigned to groups receiving either an active substance or a placebo to avoid statistical bias.

Quality & purity

HPLC (High-performance liquid chromatography): High-performance liquid chromatography is a laboratory method used to separate, identify, and quantify components in a mixture. It is widely used to verify the purity of synthesized peptides.
Mass spectrometry: Mass spectrometry is an analytical technique that measures the mass of molecules. It confirms the exact chemical structure of a peptide and ensures the synthesized molecule matches the expected profile.
Purity (%): Purity indicates what percentage of a sample is the target molecule, free of impurities and synthesis byproducts. For research purposes, a purity of over 98% is typically required.
COA — Certificate of Analysis: A Certificate of Analysis is an official document from a laboratory confirming the quality and specifications of a batch. It contains data from HPLC and mass spectrometry.
Endotoxin: Endotoxins are toxic components from the cell wall of certain bacteria that can trigger a strong immune response. Controlling their levels is critical in peptide manufacturing.
Lyophilization: Lyophilization is a freeze-drying process under vacuum that removes water from peptide solutions. This stabilizes the molecule and allows for its long-term storage as a powder.

Regulation

FDA (USA): The US Food and Drug Administration is a federal agency responsible for regulating medical products. FDA approval is a key milestone for commercializing new therapies on the American market.
EMA (European Medicines Agency): The European Medicines Agency is the institution that evaluates and supervises the safety of medicinal products in the European Union. It coordinates the approval of new molecules for member states.
BDA (Bulgarian Drug Agency): The Bulgarian Drug Agency is the national regulatory body responsible for the oversight of medicinal products and clinical trials within the country.
Research-grade molecule: Research-grade molecules are intended solely for laboratory experiments and in vitro studies. They have not undergone the strict regulatory approval procedures required for human medicines.
Pharma-grade medicine: Pharma-grade means a product is manufactured under the strictest standards and approved for human use by regulatory authorities. These products have passed all phases of clinical trials.
GMP — Good Manufacturing Practice: Good Manufacturing Practice is a system of strict guidelines ensuring that products are consistently produced and controlled according to quality standards. It minimizes risks involved in pharmaceutical production.

This glossary is purely educational. The molecules described are research reagents for laboratory use. For medical questions, consult a physician.

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Basics

Peptide

Peptides are short chains of amino acids linked by peptide bonds. They are smaller than proteins and act as crucial signaling molecules in biological systems.

E.g., insulin is one of the most well-known peptides regulating metabolism.

Amino acid

Amino acids are the fundamental building blocks of peptides and proteins. Hundreds exist in nature, but only 20 are standardly encoded in the genetic code of living organisms.

Receptor

A receptor is a specialized protein structure located on the surface or inside a cell. It recognizes and binds to specific molecules to trigger a particular cellular response.

E.g., the GLP-1 receptor is activated by semaglutide.

Agonist

An agonist is a molecule that binds to a receptor and activates it. This triggers a biological response similar to that of a naturally occurring substance in the body.

Antagonist

An antagonist is a substance that attaches to a receptor but does not activate it. Instead, it blocks access to other molecules and stops their action.

Ligand

A ligand is any molecule that forms a complex with a biomolecule, usually a receptor, to transmit a signal. Peptides often function as ligands in the endocrine system.

Signal transduction

Signal transduction is the process by which a cell converts one kind of signal or stimulus into another. This typically involves a cascade of biochemical reactions after a ligand binds to a receptor.

Signalling systems

GLP-1 (Glucagon-Like Peptide-1)

GLP-1 is an incretin hormone that stimulates insulin secretion in response to meals. Various synthetic analogs of this peptide are heavily researched and hold FDA and EMA approved status for specific metabolic conditions.

GIP (Glucose-dependent Insulinotropic Polypeptide)

GIP is another key incretin hormone that works synergistically with GLP-1 to regulate glucose metabolism. In modern science, dual agonists are being developed to activate the receptors of both peptides simultaneously.

GHRH (Growth Hormone Releasing Hormone)

GHRH is a hormone synthesized in the hypothalamus that stimulates the pituitary gland to produce and release growth hormone. Research peptides in this class mimic its action to study endocrine regulation.

GHRP (Growth Hormone Releasing Peptide)

GHRPs are a group of synthetic peptides that stimulate the release of growth hormone by binding to the ghrelin receptor. They are used in laboratory settings to investigate the mechanisms of cellular growth and metabolism.

Melanocortin system (MC3R/MC4R)

The melanocortin system is a complex network of peptides and receptors (like MC3R and MC4R) that regulate pigmentation, energy homeostasis, and inflammation. It is a frequent subject of research in neurobiology.

Kisspeptin

Kisspeptin is a neuropeptide that plays a fundamental role in initiating puberty and regulating the reproductive axis. It stimulates the release of gonadotropin-releasing hormone (GnRH).

Thymosin

Thymosins are small proteins originally isolated from the thymus gland that participate in immune response and tissue repair. In research practice, their potential to modulate cellular migration is studied.

Pharmacokinetics

Half-life

Half-life is the time required for the concentration of a substance in the body to decrease by half. This metric is crucial for determining dosing frequency in research settings.

Pharmacokinetics (PK)

Pharmacokinetics studies what the body does to a substance from the moment of its introduction. It covers the processes of absorption, distribution, metabolism, and excretion.

Pharmacodynamics (PD)

Pharmacodynamics investigates what a substance does to the body. It describes the biochemical and physiological effects of molecules and their mechanisms of action.

Bioavailability

Bioavailability is the fraction of an administered dose of a substance that reaches the systemic circulation unchanged. Intravenous administration offers 100% bioavailability, while other methods vary.

Clearance

Clearance is a measure of the rate at which the body eliminates a substance from blood plasma. It depends primarily on liver and kidney function.

Research methods

In vitro

In vitro studies are performed outside a living organism, usually in isolated cells or biological molecules in a laboratory setting. They are the first step in studying new peptides.

E.g., testing the binding of a peptide to a receptor in a petri dish.

In vivo

In vivo studies are conducted on whole, living organisms, such as animals or humans. They provide insight into the systemic effect of a molecule in a complex biological environment.

Preclinical study

Preclinical studies are the research stage prior to human testing. They involve in vitro and in vivo experiments to assess the safety and biological activity of a compound.

Phase 1/2/3 clinical trial

Clinical trials go through several phases (1, 2, and 3) to evaluate the safety, efficacy, and optimal dosing of a new drug in humans. Successful completion of all phases is mandatory for regulatory approval.

Randomised controlled trial (RCT)

A randomised controlled trial is the gold standard in science. Participants are randomly assigned to groups receiving either an active substance or a placebo to avoid statistical bias.

Quality & purity

HPLC (High-performance liquid chromatography)

High-performance liquid chromatography is a laboratory method used to separate, identify, and quantify components in a mixture. It is widely used to verify the purity of synthesized peptides.

Mass spectrometry

Mass spectrometry is an analytical technique that measures the mass of molecules. It confirms the exact chemical structure of a peptide and ensures the synthesized molecule matches the expected profile.

Purity (%)

Purity indicates what percentage of a sample is the target molecule, free of impurities and synthesis byproducts. For research purposes, a purity of over 98% is typically required.

COA — Certificate of Analysis

A Certificate of Analysis is an official document from a laboratory confirming the quality and specifications of a batch. It contains data from HPLC and mass spectrometry.

Endotoxin

Endotoxins are toxic components from the cell wall of certain bacteria that can trigger a strong immune response. Controlling their levels is critical in peptide manufacturing.

Lyophilization

Lyophilization is a freeze-drying process under vacuum that removes water from peptide solutions. This stabilizes the molecule and allows for its long-term storage as a powder.

Regulation

FDA (USA)

The US Food and Drug Administration is a federal agency responsible for regulating medical products. FDA approval is a key milestone for commercializing new therapies on the American market.

EMA (European Medicines Agency)

The European Medicines Agency is the institution that evaluates and supervises the safety of medicinal products in the European Union. It coordinates the approval of new molecules for member states.

BDA (Bulgarian Drug Agency)

The Bulgarian Drug Agency is the national regulatory body responsible for the oversight of medicinal products and clinical trials within the country.

Research-grade molecule

Research-grade molecules are intended solely for laboratory experiments and in vitro studies. They have not undergone the strict regulatory approval procedures required for human medicines.

Pharma-grade medicine

Pharma-grade means a product is manufactured under the strictest standards and approved for human use by regulatory authorities. These products have passed all phases of clinical trials.

GMP — Good Manufacturing Practice

Good Manufacturing Practice is a system of strict guidelines ensuring that products are consistently produced and controlled according to quality standards. It minimizes risks involved in pharmaceutical production.