[asuri]

Hi all

I don't really understand this... How come that if an amino group is attached to the amino acid side chain, like in arginine or lysine, the molecule is basic, but if an hydroxyl group is attached, like threonine, it is not basic?

How come the amino group can accept a H+ and a hydroxyl group cannot?

Thanks

[Arkcon]

What sort of charged group do you get when an amino accepts a proton?  What sort of group would you get if a hydroxyl could accept a proton?  What other organic molecule that contains a hydroxy accepts protons?