GAP-PS as a solution-phase process provides greater efficiency in many areas compared to SPPS. Coupling reactions are most often run with only 10% excess (1.1 eq) amino acids and coupling reagents. The efficiency in the coupling reactions results in high crude purity by reducing or eliminating deletion sequences. This high crude purity directly improves both economics and yield across chromatography.
Assessing solvent efficiency, GAP-PS runs near the saturation point of the chosen solvent compared to SPPS – which can require large amounts of solvent not only for resin suspension and swelling, but also for resin washing. GAP-PS effectively utilizes green solvents such as ethyl acetate and 2-MeTHF for synthesis because GAP-PS is not restricted by the need to adequately swell a resin support.
Compared to SPPS, GAP-PS also improves on throughput: the GAP anchor has a peptide loading of > 3 mmol / g, which is 2 – 3 times the value for the best SPPS resins. GAP-PS loading, along with the solvent benefits, means reactor and facility utilization is increased. GAP-PS also compares favorably with other solution phase methods in terms of process time; aqueous extraction steps are minimized, with phase separations taking < 2 min on average for a 4 L scale.