This paper is an autobiographical study of the author's early work on the chemical cross-linking of proteins as well as on oligomer and peptide synthesis from 1949 in Heidelberg until the synthesis of insulin in 1963 in Aachen.
This paper is an autobiographical study of the author's early work on the chemical cross-linking of proteins as well as on oligomer and peptide synthesis from 1949 in Heidelberg until the synthesis of insulin in 1963 in Aachen.
Selectively S‐Protected Cysteine Peptides. III. Synthesis of a [Ala12]‐Sheep Insulin A‐Chain Octapeptides with 6–11‐Disulfide Ring
Studying the problems of the selective sulphur protection in cysteine peptides, a octapeptide A6–13 with 6–11‐disulphide ring from the [Ala12]‐sheep insulin A‐chain was prepared by conventional synthesis using the S‐Acm and S‐Dpm group. The synthesis of the octapeptide Boc‐Cys(Acm)‐Cys(Dpm)‐Ala‐Gly‐Val‐Cys(Acm)‐Ala‐Leu‐OH 1 was carried out with the fragments Boc‐Cys(Acm)‐Cys(Dpm)‐Ala‐Gly‐OH 4 and HCl · H‐Val‐Cys(Acm)‐Ala‐Leu‐OH 8 by means of DCCI/HOOBt coupling method. Fragments 4 and 8 were synthetisized step by step without carboxyl protecting group from the carboxyterminal end using the Boc‐amino protecting group. Treatment of 1 with iodine in methanol gives formation of the octapeptide 2 with 6–11 – disulphide ring. The Dpm‐thiol protecting group is completely stable during this step.
Mass spectra of S‐Dpm and S‐Acm protected compounds are discussed.
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