Abstract: The present invention relates to a method for producing an acetalization product of an ethylene/vinyl alcohol copolymer by acetalization of an ethylene/vinyl alcohol copolymer, wherein the ethylene/vinyl alcohol copolymer is a porous object.

Abstract: An object of the present invention is to provide a novel method for producing a peptide utilizing a ligation reaction in which ligation efficiency is excellent and side reactions to other functional groups in the peptide are hard to occur, in comparison with the conventional native chemical ligation methods utilizing the thiol auxiliary group. The present invention provides a method for producing a peptide which comprises a step of causing a first peptide and a second peptide to react in the presence of a reducing agent to obtain a ligated product of the first peptide and the second peptide, wherein the first peptide contains, at the C-terminal end, an amino acid derivative having a thioester group, and the second peptide contains, at the N-terminal end, a serine or threonine derivative having a thiol auxiliary group.

Abstract: An object of the present invention is to provide a method for synthesizing a peptide thioester by using a compound that can be easily obtained within a relatively short time under conditions in which a side reaction is unlikely to occur. In the present invention, a thioester bond is formed by elongating a peptide chain using N-alkyl cysteine as the C-terminal amino acid according to the Fmoc method, carrying out deprotection, and then causing the peptide bond to undergo N—S transfer to the thiol group of N-alkyl cysteine under weak acidic conditions.