Dimerisation
Definition
Two molecules associating or bonding into one unit. For peptides it most often means an unintended disulfide-linked dimer, which appears as a distinct peak at twice the expected mass.
What this means for research sourcing
Structure and identity terms are what a certificate of analysis is written in. Every Volta compound ships with its sequence, molecular weight and measured purity, so these terms map directly onto the specification on the product page.
Related Terms in Chemistry & Structure
Hydrophilicity
Affinity for water. In peptides it is set by the balance of polar and charged residues, and together with its opposite it governs solubility, how the chain folds, and where it elutes in reversed-phase chromatography.
Lipophilicity
Affinity for fats and non-polar solvents, usually quantified as a partition coefficient. Acylation raises it deliberately, which is how several long-acting analogues achieve albumin binding.
Quaternary Structure
The arrangement of two or more folded chains into one functional assembly. It is the level above tertiary structure and applies only to multi-subunit molecules, which most research peptides are not.
Protein Folding
The process by which a chain adopts its three-dimensional shape, driven mainly by burying hydrophobic residues away from water. Activity usually depends on the fold, which is why a denatured molecule can be chemically intact and inert.
Glycosylation
Attachment of sugar chains to a protein, typically at asparagine or at serine and threonine. It affects stability, solubility and clearance, and it is a reason a recombinant molecule may differ from the same sequence made synthetically.
Post-Translational Modification
Any chemical change made to a chain after it is assembled: acetylation, amidation, phosphorylation, glycosylation and others. The same sequence with and without one is two different molecules with two different masses.
Residue
One amino acid once it sits inside a chain, so called because the condensation that formed the bond left part of the free molecule behind. A peptide described as fifteen residues long has fifteen amino acids in it.
N-Terminus and C-Terminus
The two ends of a peptide: the N-terminus carries the free amino group, the C-terminus the free carboxyl group. Sequences are written N to C by convention, and end modifications such as acetylation or amidation are named for whichever terminus they cap.