title: Solid-phase peptide synthesis at elevated temperatures: a search for and optimized synthesis condition of unsulfated cholecystokinin-12.
abstract: A systematic investigation of solid-phase peptide synthesis at elevated temperatures using the well-known aggregating peptide acyl carrier protein (65-74) and the unsulfated cholecystokinin-8 as models is presented. The main goal of the investigation was the determination of an optimized experimental condition for the synthesis of unsulfated cholecystokinin-12. Of the elevated temperatures used, 60 degrees C was the most appropriate. The efficiency of N,N'-diisopropylcarbodiimide/1-hydroxybenzotriazole (DIC/HOBt) in 25% dimethyl sulfoxide (DMSO)/toluene at this temperature was similar to that of 2-(1-H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU). Interestingly, this coupling reagent was more efficient than TBTU, benzotriazol-1-yl oxy-tris(dimethylamino)phosphonium and O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate in N-methylpyrrolidone. 25% DMSO/toluene proved to be suitable for the swelling of the resins phenylacetamidomethyl, methylbenzhydrylamine, hydroxymethylphenoxy, 4-(benzyloxy)-2',4'-dimethoxybenzhydrylamine, 4-(2',4'-dimethoxyphenyl-Fmoc-aminomethyl)phenoxy and (4-succinylamido-2',2',4'-trimethoxy)benzhydrylamine. Those 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 encountered. These data confirm the usefulness of solid-phase peptide synthesis at elevated temperatures and extend its applicability.
authors.affiliation: Department of Biochemistry, University of São Paulo, Brazil.
authors.forename: L M
authors.initials: LM
authors.lastname: Varanda
authors.forename: M T
authors.initials: MT
authors.lastname: Miranda
mesh_terms: D000213:Acyl Carrier Protein / Q000138:chemical synthesis; D002766:Cholecystokinin / Q000138:chemical synthesis*; D002851:Chromatography, High Pressure Liquid; D010446:Peptide Fragments / Q000138:chemical synthesis* / Q000302:isolation & purification; D012844:Sincalide / Q000138:chemical synthesis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013431:Sulfates / Q000737:chemistry; D013696:Temperature
chemical_list: D000213:Acyl Carrier Protein; D010446:Peptide Fragments; D013431:Sulfates; D002766:Cholecystokinin; D012844:Sincalide