The invention relates to a method for preparing an optionally N-protected amino acid C-terminal ester or an optionally N-protected peptide C-terminal ester, comprising transesterifying the C-terminal t-alkyl ester of the amino acid or the C-terminal t-alkyl ester of the peptide with an alcohol (other than the t-alcohol corresponding to the t-alkyl group of the ester) in the presence of a hydrolytic enzyme (E.C. 3).The invention further relates to a method for preparing a peptide comprising coupling an activated, N-protected, amino acid C-terminal ester or an optionally N-protected peptide C-terminal ester with an optionally C-terminal protected amino acid or an optionally C-terminal protected peptide via a peptide bond, in the presence of an enzyme catalysing peptidic bond formation.