1,6-AnhMurNAc derivatives for assay development of amidase AmiD

Various peptidoglycan fragments were synthesized from two anhydro-muramic acid derivatives protected with a Bn or a PMB group at the 4th position, in homogenate phase or on a solid support. In order to facilitate HPLC detection, a chromophoric group was attached to the peptide chain. The periplasmic amidase sAmiD of Escherichia coli was used to cleave the amide bond between the lactyl group of the MurNAc and the α-amino group of l-Ala where the peptide chain was at least a dipeptide (l-Ala-γ-d-Glu) amidated by benzylamine on the γ-carboxyl group of d-Glu. In the presence of a tripeptide chain (l-Ala-γ-d-Glu-l-Lys) or a tetrapeptide chain (l-Ala-γ-d-Glu-m-A2pm-d-Ala) higher hydrolysis rates were observed. We have also demonstrated that the presence of TNB on the ε-amino group of l-Lys only has a small influence on the hydrolysis capacity of sAmiD.

Peptido 1,6-anhMurNAc derivatives were obtained easily in good yield using a solid support synthesis. Biological studies with sAmiD showed that anhMurNAc-l-Ala-γ-d-Glu-l-Lys 28 with TNB as chromophoric group on the ε-amino group of l-Lys is a good candidate for the development of a sensitive enzyme assay of sAmiD.Figure optionsDownload as PowerPoint slide