FIG 2.
Penicillin G effect on VanYn (A) and VanXat (B) activities. d,d-Carboxypeptidase and d,d-peptidase activities were determined by measuring the amount of d-Ala released by hydrolysis of the Nϵ-acetyl-l-Lys-d-Ala-d-Ala tripeptide and d-Ala-d-Ala dipeptide, respectively, using a d-amino acid oxidase coupled to a peroxidase (22). Different concentrations of penicillin G (PEN) (white bar, 0 mM; gray bar, 10 mM; black bar, 50 mM black bar; striped bar, 100 mM) were added to the assay mixture. (A) VanYn activity was measured in membrane extracts of Nonomuraea sp. ATCC 39727 and its recombinant strains (listed in Table 1) grown in VSP medium for 72 h. (B) VanXat activity was measured in the cytoplasmic fraction of the Nonomuraea sp. strain carrying pST30 grown in VSP for 72 h.