Please answer both questions.

Please indicate how water might hydrogen bond with D$-$Ala$-$D$-$Lac excluding the terminal amine and terminal carboxylic acid

This change in hydrogen bonding pattern is all the bacteria needs to survive. Interestingly changing an oxygen in vancomycin aglycone $($compound $5$ below$)$ to an $NH($compound $6$ below$)$ restores activity against VRE, strains with D$-$Ala$-$D$-$Lac, and compound $6$ is still active against strains with $($D$-$Ala$-$D$-$Ala$).$ Why?