SOLID-PHASE PEPTIDE-SYNTHESIS AT ELEVATED-TEMPERATURES - A SEARCH FORAN OPTIMIZED SYNTHESIS CONDITION OF UNSULFATED CHOLECYSTOKININ-12

A systematic investigation of solid-phase peptide synthesis at elevate d temperatures using the well-known aggregating peptide acyl carrier p rotein (65-74) and the unsulfated cholecystokinin-8 as models is prese nted. The main goal of the investigation was the determination of an o ptimized experimental condition for the synthesis of unsulfated cholec ystokinin-12. Of the elevated temperatures used, 60 degrees C was the most appropriate. The efficiency of ,N'-diisopropylcarbodiimide/1-hydr oxybenzotriazole (DIG/HOBt) in 25% dimethyl sulfoxide (DMSO)/toluene a t this temperature was similar to that of 1-H-benzotriazole-1-yl)-1.1. 3.3-tetramethyluronium tetrafluoroborate (TBTU). Interestingly, this c oupling reagent was more efficient than TB?ZI, benzotriazol-1-yl oxytr is(dimethylamino)phosphonium and 7-azabenzotriazol-1-yl)-1,1,3,3-tetra methyluronium hexafluorophosphate in N-methylpyrrolidone. 25%DMSO/tolu ene proved to be suitable for the swelling of the resins phenylacetami domethyl, methylbenzhydrylamine, hydroxymethylphenoxy, 4-(benzyloxy)-2 ',4'-dimethoxybenzhydrylamine, 4-(2',3'dimethoxyphenyl-Fmoc-aminomethy l) ??phenoxy and succinylamido-2',2',4'-trimethoxy)benzhydrylamine. Th ose polymeric supports were fully compatible with the approach. Under the optimized synthesis condition found in these studies (temperature of 60 degrees C, DIC/HOBt as coupling reagent and 25% DMSO/toluene as solvent), no difficulties related to the aggregation phenomenon were e ncountered. These data confirm the usefulness of solid-phase peptide s ynthesis at elevated temperatures and extend its applicability. (C) Mu nksgaard 1997.