[LidaOliver]

I am supposed to determine all chiral centers, which I marked in red, then find the absolute configuration, which I labeled in blue; which I determined should be (R). Then, I need to draw all hydrogen bonds that it will form with water in pH=7, which I labeled orange but without the water molecules at the end.

Am I correct that there is only 1 chiral center? I am still getting used to finding them in larger molecules... I am also unsure about the hydrogen bonding with the amine group on the end. Will oxygen of water be attracted to the hydrogens in the amine group? The positive charge means that the amine does not have electrons and hydrogens of water will not be attracted to it? Also, will it mainly be the oxygens and nitrogens on the ends or that protrude out the ones that will be forming hydrogen bonds? How does the pH effect the hydrogen bonding? I know that a low pH will denature enzymes, but is there a general rule? (I am not even going to attempt (b) until I understand this first...)

If anyone also has any biochem resource sites that they find helpful, please share!! my book just is not helping me enough.. thanks in advance!!! & sorry if the molecule looks too small on the screen, I tried my best!

[Doc Oc]

Yes, there is only one chiral center.  Yes, the oxygen of water would participate in hydrogen bonding with the ammonium.

As for the pH effect, think about it in terms of Bronsted acids.  Lowering the pH means there's more acid, and therefore more H+.  What will happen to the oxygens/nitrogens in the molecule if there's a lot of H+ around and how will that affect their hydrogen bonding ability?  What if you raise the pH?

[Babcock_Hall]

Water can be both a hydrogen bond donor and acceptor.  Therefore, water can accept hydrogen bonds from the ammonium group, which is the donor.  But it can also donate hydrogen bonds to oxygen (or nitrogen) atoms with lone pairs of electrons.   It seems to me that you have not marked all of the oxygen atoms that could accept a hydrogen bond from water.  There are a couple of books like "PDQ Biochemistry" that might be of interest.