title: Carbonyldiimidazole/1-hydroxybenzotriazole activation in polymer phase synthesis of the arginine rich proalbumin hexapeptide extension.
abstract: The synthesis on different polymer phases of Arg-Gly-Val-Phe-Arg-Arg, the proalbumin extension, is reported. The peptide was prepared both on a 0.5% cross-linked polystyrene gel containing 2-oxoethyl bromide anchor functions and on a 1% cross-linked chloromethyl polystyrene. For temporary blocking of the amino groups we utilized the 2-(3,5-dimethoxyphenyl) propyl-(2)-oxycarbonyl (Ddz). The guanidino groups of the three arginine moieties were protected by the 4-toluenesulfonyl (Tos) group. As coupling procedure we used 1 equiv. carbonyldiimidazole (CDI)/2 equiv. 1-hydroxybenzotriazole (HOBt). The C-terminal activation of the Ddz-amino acids with CDI/HOBt made it possible to recover the excess Ddz-amino acids in 60-80% yield. We also investigated different procedures to cleave the 2-oxoethyl ester bond between the peptide and the polymer. This bond was completely stable against trifluoromethanesulfonic acid and was split by 1 N triethylamine in methanol/dioxane 1:1 (v/v) + 1 vol% 1 N NaOH. The optical rotation and HPLC properties of Arg-Gly-Val-Phe-Arg-Arg from this synthesis are identical to the product from a different synthesis published earlier.
mesh_terms: D000418:Albumins / Q000138:chemical synthesis*; D001120:Arginine; D009842:Oligopeptides / Q000138:chemical synthesis*; D011108:Polymers; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational
chemical_list: D000418:Albumins; D009842:Oligopeptides; D011108:Polymers; D011498:Protein Precursors; D001120:Arginine