What is Aspartimide formation?

Aspartimide formation 1,2 is caused by repeated exposure of aspartic acid containing sequences to bases like piperidine and can result ultimately in the generation of 9 different by-products (Figure 1)3–8. Furthermore, as they have the same mass as the target, the presence of these side products is hard to detect.

Why is DMF used in peptide synthesis?

Dimethylamine is reactive toward the Fmoc protecting group and may remove it. This could result in excess couplings, and accordingly impure products. DMF is cheaper than NMP, so many peptide chemists use it in spite of its tendency to release reactive amines.

What is the first step in a solid phase peptide synthesis?

Introduction. Solid-phase peptide synthesis (SPPS) involves the successive addition of protected amino acid derivatives to a growing peptide chain immobilized on a solid phase, including deprotection and washing steps to remove unreacted groups and also side products.

What is the role of Fmoc?

Fmoc belongs to a set of urethane protecting groups including the benzyl carbamate (benzyloxycarbonyl) and Boc protecting groups that suppress racemisation during activation and coupling. Carpino and Han introduced the Fmoc group for solution chemistry, but it proved unsuitable 8, 9.

How do you prevent Aspartimide formation?

One of the simplest strategies for limiting aspartimide formation is to change the Fmoc-removal conditions. Simply adding 0.1 M hydroxybenzotriazole (HOBt) to the piperidine solution has been shown to reduce aspartimide formation significantly.

What is Aspartimide?

Aspartimide formation has long been recognized as the important side-reaction in Solid Phase Peptide Synthesis (SPPS). The reason is that it can occur in both basic and acidic conditions. Also in the solid and liquid phase. The side-chains of aspartate residues during SPPS are protected with an ester function.

How do you remove Dimethylamine from DMF?

Dimethylamine degradation impurities can be removed by sparging degraded samples with an inert gas such as argon or by sonicating the samples under reduced pressure. As its name indicates, it is a derivative of formamide, the amide of formic acid. DMF is a polar (hydrophilic) aprotic solvent with a high boiling point.

Is DMF soluble in DCM?

DMF is more soluble in DCM , compared to ETOAc. Better try to extract in ETOAc or ether. DMF is soluble in cold or chilled water.