Ultrafast Peptide Synthesis at Elevated Temperature

Summary

The Liberty PRIME™ 2.0 microwave peptide synthesizer is the most advanced system available for peptide synthesis. It is based on the use of a new one-pot coupling and deprotection methodology for solid phase peptide synthesis that drastically reduces cycle time and waste usage to unprecedented levels. The system provides a complete cycle time of only 2 min 10 sec (for all 20 standard Fmoc amino acids) with only 8 mL of chemical waste produced, half the amount of CEM’s highly efficient Liberty Blue 2.0 peptide synthesizer. The Liberty PRIME 2.0 HT24 is an ideal system for high-throughput peptide synthesis of both standard and complex peptides, with the ability to automatically synthesize up to 24 peptides in a day.

Introduction

Traditional solid phase peptide synthesis involves the use of iterative and separate deprotection and coupling steps with washing in-between. This is based on the assumption that undesirable amino acid insertions can occur without complete draining and washing between each step. In 2013 our group demonstrated that washing after the coupling step can be eliminated without effect on peptide purity.¹

The Liberty PRIME takes this further by using a new one-pot coupling and deprotection process as shown in Figure 1.² This technique involves addition of the deprotection reagent (base) directly to the undrained post-coupling mixture. The ability to do this is based on the insight that faster reaction kinetics in the solution phase promote rapid hydrolysis or selfcondensation of the active ester, thereby avoiding potential side reactions at the resin bound amino functionality. The Fmoc removal then proceeds uninterrupted at elevated temperature. An optimized use of reagents results in an essentially neutral reaction mixture towards the end of deprotection step. This new procedure offers several advantages such as (a) approximately 90% reduction in solvent requirement for the deprotection step, (b) 75% reduction in solvent requirement for post-deprotection washings, (c) faster deprotection step, since the microwave ramp time is not needed, and (d) shorter cycle time due to absence of post-coupling drain step.