Cleavage
Definition
Releasing the finished chain from the resin, usually with trifluoroacetic acid, which also strips most side-chain protection in the same step. Scavengers are included to catch the reactive fragments this generates.
In more detail
Cleavage releases the finished chain from the resin, usually with trifluoroacetic acid, and in Fmoc chemistry the same treatment removes most side-chain protection at once.
The step generates reactive fragments as those groups come off, and left alone they will attach themselves to sensitive residues and create impurities. Scavengers are included in the cleavage mixture to catch them, and the composition of that mixture is chosen for the particular residues a sequence contains.
Trifluoroacetic acid is also where the counterion comes from. A peptide made this way is typically isolated as a trifluoroacetate salt, which is mass in the vial that is not peptide and is one of the reasons net peptide content is measured.
Terms used in this definition
Other entries this definition refers to.
Where this term comes up
Entries whose definition mentions Cleavage.
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
Capping
Permanently blocking any chain that failed to couple, so it cannot react in later cycles. It converts a deletion impurity that would be hard to separate into a short truncated one that is easier to remove.
Coupling Reagent
The activator that turns a carboxylic acid into a form reactive enough to form an amide bond with the next amino group. Coupling efficiency compounds over a synthesis, so a small per-step loss becomes a large one over a long sequence.
Carbodiimide
A class of coupling reagent including DIC and EDC, usually paired with an additive to suppress side reactions. They are inexpensive and widely used, and the by-product they form differs in how easily it washes away.
HOBt (Hydroxybenzotriazole)
A coupling additive that forms a more selective active ester, raising yield and suppressing racemisation. Its shipping restrictions as a dry solid are part of why alternatives such as Oxyma came into use.
Uronium Salt
A family of fast coupling reagents including HBTU and HATU. They activate quickly and are used where a difficult coupling needs the help, at a higher cost than a carbodiimide.
Oxyma Pure
An additive used in place of HOBt, giving comparable suppression of racemisation without the same handling classification. It is typically paired with a carbodiimide.
Piperidine
The base used to remove the Fmoc group, usually as a 20% solution in DMF. It appears once per residue in a standard synthesis, and the by-product it forms is monitored to confirm each deprotection happened.
Resin
The insoluble polymer bead the chain is assembled on in solid-phase synthesis. Anchoring the chain to it is what lets excess reagents and by-products be washed away at every step, which is the entire advantage of the method.