PEGylation
Definition
Attaching polyethylene glycol chains to a peptide. The added hydrodynamic bulk slows glomerular filtration and shields the backbone from enzymes, so the molecule circulates for longer. PEG-MGF carries the name of the modification.
What this means for research sourcing
Foundational terminology for researchers new to peptide science. Volta's introductory resources connect these fundamentals to the compounds available for study.
Related Terms in Basics
Acylation
Attaching a fatty acid chain so the molecule binds reversibly to serum albumin. The albumin-bound fraction acts as a circulating reservoir and clearance slows from hours to days. GLP-1 SM and cagrilintide both use it.
DAC (Drug Affinity Complex)
A maleimidopropionic acid linker that couples to albumin after administration. On CJC-1295 it takes the half-life from minutes to roughly eight days, which is the whole difference between the DAC and no-DAC versions of that compound.
Amino Acid
The unit a peptide is built from. Twenty of them are used to assemble human proteins, each carrying an amino group, a carboxyl group and a distinguishing side chain, and it is the side chains that decide how a finished peptide folds and what it binds.
Peptide
A chain of amino acids joined by peptide bonds, conventionally fewer than about 50 of them. The cut-off between a peptide and a protein is a convention rather than a chemical boundary, and several compounds supplied for research sit either side of it.
Protein
A long amino acid chain, usually above the 50-residue convention, that folds into a defined three-dimensional structure. Collagen, insulin and antibodies are proteins; the shorter chains studied as research peptides are not, although the chemistry of the backbone is identical.
Peptide Bond
The amide link between two amino acids, formed when the carboxyl group of one condenses with the amino group of the next and a molecule of water is lost. A run of these bonds is the backbone that makes a molecule a peptide.
Sequence
The order of the amino acids along a chain, written N-terminus first in one-letter or three-letter codes. The sequence is the compound's identity: two materials with different sequences are different substances whatever name is printed on the vial.
Analogue
A known peptide altered on purpose, by substituting a residue, shortening the chain or attaching something to it, so that it resists degradation or binds differently while still acting at the same target. GLP-1 SM is an analogue of GLP-1.
