Study of Hydrogenolytic Cleavage of Peptide-Resin Benzyl Ester Bonds for Synthesis of Protected Fragments of the Human Leukocyte Interferon
نویسندگان
چکیده
Three Boc-protected fragments of the human leukocyte interferon, LeIFA, have been synthesized: I, BOC LeIFA (99-105) (BOC-Val-Ile-Gln-Gly-Val-Gly-Val); II, BOC LeIFA (116-119) (BOC-Ile-Leu-Ala-Val); III, BOC LeIFA (123-126) (BOC-Phe-GlnArg(Tos)-Ile). The presence of the Boc-group was desired so that these peptides could serve as intermediates in fragment condensation toward larger segments of interferon. To achieve these intermediates, a study was desirable on three methods of cleavage of the benzyl ester-polymer bonds. It was found that hydrogenolysis with hydrogen and palladium generated in situ was distinctly superior to transfer hydrogenation with ammonium formate or cyclohexene. An effective swelling of the peptide-resin to allow penetration of palladium acetate into the matrix and mobility of the peptide chains on the resin to expose the benzyl ester bond to hydrogenolysis appear to be essential conditions for the best cleavage.
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