Peptide Glossary

Welcome to our comprehensive glossary of peptide-related terms and concepts. This resource is designed to help researchers, students, and professionals navigate the complex terminology of peptide science. The definitions provided are for educational and reference purposes only.

A

Amino Acid: The building blocks of peptides and proteins. There are 20 standard amino acids that can be combined in various sequences to form peptides and proteins with different structures and functions.

B

Bioavailability: The proportion of a peptide that enters circulation when introduced into the body and is available for biological effect. Many peptides have low oral bioavailability due to degradation in the digestive system.

C

C-terminus: The end of a peptide or protein chain that has a free carboxyl group (-COOH).

D

Disulfide Bridge: A covalent bond formed between the sulfur atoms of two cysteine residues. These bonds play a crucial role in stabilizing the three-dimensional structure of many peptides and proteins.

E

Endogenous Peptides: Peptides that are naturally produced within an organism. Examples include insulin, endorphins, and growth hormone-releasing peptides.
Exogenous Peptides: Peptides that come from outside an organism, either through synthetic production or extraction from other sources.

H

HPLC (High-Performance Liquid Chromatography): An analytical technique used to separate, identify, and quantify components in a mixture. In peptide research, HPLC is commonly used to assess peptide purity.

L

Lyophilization: A freeze-drying process used to preserve peptides by removing water from the frozen product under a vacuum. This process extends shelf life and maintains peptide stability.

M

Mass Spectrometry: An analytical technique that measures the mass-to-charge ratio of ions. It is used to determine the molecular weight and structure of peptides, confirming their identity and purity.
Molecular Weight: The sum of the atomic weights of all atoms in a peptide molecule, typically expressed in daltons (Da) or g/mol. It's an important characteristic for peptide identification and analysis.

N

N-terminus: The end of a peptide or protein chain that has a free amino group (-NH₂). By convention, peptide sequences are written from N-terminus to C-terminus.

P

Peptide Bond: A covalent chemical bond formed between two amino acids during protein synthesis. It occurs when the carboxyl group of one amino acid reacts with the amino group of another, releasing a water molecule.
Peptide Synthesis: The process of creating peptides by linking amino acids in a specific sequence. Common methods include solid-phase peptide synthesis (SPPS) and liquid-phase peptide synthesis.
Purity: The percentage of the target peptide present in a sample relative to impurities. High purity is crucial for research applications to ensure reliable and reproducible results.

R

Receptor: A protein molecule that receives chemical signals from outside a cell. Many peptides function by binding to specific receptors, triggering cellular responses.
Reconstitution: The process of dissolving a lyophilized (freeze-dried) peptide in an appropriate solvent to create a solution for research use.

S

Sequence: The specific order of amino acids in a peptide chain, which determines its structure and function.
Solid-Phase Peptide Synthesis (SPPS): A technique for creating synthetic peptides where the growing peptide chain is attached to an insoluble support material, allowing for efficient synthesis and purification.
Structure-Activity Relationship (SAR): The relationship between the chemical structure of a peptide and its biological activity. Understanding SAR helps researchers design peptides with specific functions.

T

Therapeutic Peptides: Peptides used as medications to treat various conditions. Examples include insulin for diabetes and oxytocin for inducing labor.

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