Further studies on peptide synthesis at high temperature
It is well known that conventional heating and microwave irradiation accelerate the reactions and may minimize aggregation in stepwise Solid-Phase Peptide Synthesis (SPPS) [1, 2, 3, 4, 5]. Nevertheless, SPPS-conventional heating and SPPS-microwave irradiation have not yet been employed routinely. This is credited mainly to the fear of the enhancement of secondary reactions.
In previous works we investigated the following aspects of stepwise SPPS-conventional heating: suitability of a few solvent systems, swelling properties of a few polymeric resins, efficiency of a few coupling agents and occurrence of enantiomerization. Among the temperatures and solvents studied, 60°C and 25%DMSO/toluene were the most favorable. No difficulties related to the aggregation phenomenon were encountered. In 25%DMSO/toluene at 60°C, enantiomerization was not significantly enhanced during the syntheses of Ac-Ile-Gly, dTyr-Lys-Trp, Ile-Phe-Gly-Thr-NH2 using DIC or TBTU/DIPEA [2, 3, 4].
KeywordsMicrowave Irradiation Peptide Synthesis Chiral Selector Conventional Heating Polymeric Resin
We thank FAPESP (financial support to M™M), CNP q (postgraduate scholarship to CL), CEM Corporation (manual microwave peptide synthesizer), J. Gerhardt [total hydrolyses in 6 N DCl/D2O and GC/MS in C.A.T.GmBH & Co. Cromatographie und Analysentechnik KG (Tübingen, Germany)], C.W. Liria (amino acids analyses) and F.M. Prado (technical support in the LC/ESI-MS analyses).
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