Peptide Glossary

A substance that binds to a receptor and activates it, triggering a biological response. Many peptides act as agonists to specific hormone receptors.

The building blocks of peptides and proteins. There are 20 standard amino acids that combine in various sequences to form peptides. Each amino acid has a unique side chain that determines its chemical properties.

Relating to the metabolic process of building up tissues and molecules. Anabolic peptides promote muscle growth, tissue repair, and overall cellular construction.

A substance that binds to a receptor but blocks or reduces its activity, preventing the natural ligand from activating it.

Sterile water containing 0.9% benzyl alcohol as a preservative. Used to reconstitute peptides for injection, it allows the solution to be stored for extended periods without bacterial growth.

The strength of interaction between a peptide and its target receptor. Higher binding affinity generally indicates more potent activity at lower concentrations.

The proportion of a peptide that enters circulation and reaches its target site when administered. Subcutaneous injection typically provides higher bioavailability than oral administration for peptides.

The end of a peptide chain with a free carboxyl group (-COOH). Peptide sequences are conventionally written from N-terminus to C-terminus.

Chemical Abstracts Service registry number, a unique numerical identifier assigned to every chemical substance. Used to unambiguously identify specific peptide compounds.

Relating to the metabolic breakdown of complex molecules into simpler ones, often releasing energy. The opposite of anabolic processes.

The natural 24-hour biological cycle that affects hormone release patterns. Many peptide protocols are timed to align with these rhythms for optimal effectiveness.

A peptide with a circular structure formed by a bond between the N- and C-termini, or between two side chains. Cyclic structures often increase stability and receptor selectivity.

The reduced response to a peptide after repeated exposure, often due to receptor downregulation. This is why cycling protocols are important for maintaining effectiveness.

A liquid used to dissolve or dilute a lyophilized peptide for administration. Common diluents include bacteriostatic water and sterile saline.

The measured amount of a peptide administered at one time. Dosages are typically expressed in micrograms (mcg) or milligrams (mg) and may be based on body weight.

Produced naturally within the body. Many research peptides are synthetic versions of endogenous hormones or signaling molecules.

Originating from outside the body. Administered peptides are exogenous substances that mimic or modulate endogenous processes.

A regulatory mechanism where the output of a process affects its own production. Negative feedback loops often regulate hormone levels to maintain homeostasis.

See Lyophilized. A preservation method that removes water from peptides through sublimation, leaving a stable powder that can be stored long-term.

A peptide hormone produced by the pituitary gland that stimulates growth, cell reproduction, and regeneration. Many peptides work by stimulating natural GH release.

A hypothalamic peptide that stimulates the pituitary gland to release growth hormone. Synthetic GHRH analogs like CJC-1295 are used in research.

A class of synthetic peptides that stimulate growth hormone release through the ghrelin receptor. Examples include GHRP-6, GHRP-2, and Ipamorelin.

An incretin hormone that regulates blood sugar and appetite. GLP-1 receptor agonists like Semaglutide are studied for metabolic research.

The time required for half of a peptide dose to be eliminated from the body. Longer half-lives allow for less frequent dosing but may increase accumulation.

The tendency of biological systems to maintain stable internal conditions. Many peptides influence homeostatic mechanisms.

A region of the brain that controls many bodily functions including hormone release. The hypothalamus produces several important regulatory peptides.

A hormone with structural similarity to insulin that mediates many effects of growth hormone. IGF-1 promotes cell growth and has anabolic effects.

A group of metabolic hormones that stimulate insulin secretion in response to meals. GLP-1 and GIP are the main incretins.

A small-gauge syringe designed for insulin injection, commonly used for peptide administration. Marked in units (100 units = 1 mL), making precise dosing easier.

An injection route where the peptide is administered directly into muscle tissue. Generally allows for slower absorption compared to subcutaneous injection.

A molecule that binds to a specific receptor to produce a biological effect. Peptides often function as ligands for hormone receptors.

A peptide with a straight chain structure, as opposed to cyclic peptides. Most naturally occurring peptides are linear.

Freeze-dried to remove water while preserving structure and activity. Most research peptides are supplied in lyophilized powder form for stability.

A family of peptide hormones that bind to melanocortin receptors, affecting pigmentation, energy homeostasis, and sexual function. Examples include Melanotan II.

The chemical processes in the body that convert food into energy and building blocks. Peptides can influence metabolic rate and efficiency.

One millionth of a gram (0.001 mg). Many peptide dosages are measured in micrograms due to their high potency.

One thousandth of a gram. Peptide vial sizes are typically measured in milligrams (e.g., 5mg, 10mg vials).

A notation showing the number and type of atoms in a molecule. For peptides, this indicates their elemental composition.

The sum of atomic weights of all atoms in a molecule, measured in Daltons (Da). Peptide molecular weights typically range from 500-5000 Da.

The end of a peptide chain with a free amino group (-NH2). Peptide sequences are written starting from the N-terminus.

A peptide that acts as a neurotransmitter or neuromodulator in the nervous system. Examples include Semax and Selank.

A peptide containing 2-20 amino acids. Most research peptides fall into this category.

A short chain of amino acids linked by peptide bonds. Peptides typically contain 2-50 amino acids and have diverse biological functions.

The chemical bond formed between the carboxyl group of one amino acid and the amino group of another, joining amino acids into a peptide chain.

The study of how the body absorbs, distributes, metabolizes, and excretes a drug or peptide. Understanding pharmacokinetics helps optimize dosing protocols.

The master endocrine gland at the base of the brain that releases many important hormones including growth hormone. Many peptides target pituitary function.

A peptide containing more than 20 amino acids. Proteins are made of one or more polypeptide chains.

A structured plan for peptide administration including dosage, timing, frequency, and duration. Proper protocols help maximize benefits while minimizing risks.

A unique identifier assigned to chemical compounds in the PubChem database, a free chemistry database maintained by NCBI.

The secretion of hormones in discrete bursts rather than continuously. Natural growth hormone is released in pulses, which some peptide protocols aim to mimic.

A protein molecule that receives and responds to signals from specific ligands. Peptides exert their effects by binding to specific receptors on cell surfaces.

The process of adding a diluent to lyophilized peptide powder to create an injectable solution. Proper reconstitution technique is critical for peptide stability.

An amino acid unit within a peptide chain. When amino acids join to form peptides, they become residues.

A substance that promotes the secretion of another substance. Growth hormone secretagogues stimulate the pituitary to release GH.

The specific order of amino acids in a peptide chain. The sequence determines the peptide's structure, function, and biological activity.

The ability of a peptide to maintain its structure and activity over time. Factors affecting stability include temperature, light, pH, and oxidation.

The practice of combining multiple peptides in a protocol to achieve synergistic effects. Common stacks pair GHRH analogs with GHRPs.

Purified water that has been sterilized and is free of microorganisms. Unlike bacteriostatic water, it lacks preservatives and should be used immediately after opening.

An injection route where the peptide is administered into the fat layer just beneath the skin. The most common route for peptide administration.

A peptide created through chemical synthesis rather than extracted from biological sources. Allows for precise control over purity and modifications.

A rapid decrease in response to a drug after repeated doses. Similar to desensitization, it's why peptide cycling is often recommended.

A family of peptides originally isolated from the thymus gland. Thymosin Alpha-1 and Thymosin Beta-4 (TB-500) are studied for immune and healing properties.

International Unit, a measurement of biological activity. Growth hormone is often measured in IUs. Also refers to markings on insulin syringes (100 units = 1 mL).

A small container used to store lyophilized peptides. Typically sealed with a rubber stopper that allows needle access while maintaining sterility.