Development of a fully automated multichannel peptide synthesizer with integrated TFA cleavage capability

A fully automated multichannel peptide synthesizer has been constructed which performs simultaneous and rapid assembly of peptides on a 20-200 mumol scale. In situ activation of amino acids using BOP or PyBOP was chosen to give an optimized coupling chemistry. Specially designed blocks of valves, with a zero dead volume combined with an original circuitry, permit the distribution of amino acids derivatives and reagents pre-dissolved in DMF. Either Boc or Fmoc chemistry can be adapted on the synthesizer. In Boc synthesis a very rapid protocol involving Boc group deprotection in neat TFA, followed by the concomitant steps of neutralization and coupling, allows the addition of three amino acids per hour on each channel. In Fmoc chemistry we have integrated into the synthesizer an automatic TFA cleavage system that allows the peptides to be cleaved from the resin directly within the reactors used for synthesis. The stability of the Fmoc amino acid derivatives in solution in DMF was investigated, and decomposition was found to be insignificant during the time-span of a synthesis. The satisfactory performance of the instrument was demonstrated by routine synthesis of 15-20 mer peptides.