Chemical synthesis of peptidoglycan mimetic-disaccharide-tetrapeptide conjugate and its hydrolysis by bacteriophage T5, RB43 and RB49 L-alanyl-D-glutamate peptidases.

The resulting glycopeptide mimetic was shown to interact with the studied enzymes. Its hydrolysis occurred through the bond between l-Ala and d-Glu. This artificial substrate mimetic was hydrolyzed by enzymes at different rates, which decreased outside the pH optimum. The EndoT5 demonstrated the lowest hydrolysis rate, whereas the EndoRB49-driven hydrolysis was the fastest one, and EndoRB43 displayed an intermediate potency. These observations are consistent with the hypothesis that EndoRB49 is characterized by the lowest selectivity, and hence the potentially broader spectrum of the peptidoglycan types subjected to hydrolysis, which was put forward in the previous study. We also show that to hydrolyze this glycopeptide mimetic, enzymes approach the glycopeptide near the methyl groups of all three alanines.