1. The problem statement, all variables and given/known data The following structures illustrate hydrogen bonding interactions between amino acid side chains and/or backbone atoms within a protein structure. In which of the following figures are the structures and hydrogen bonding completely correct? 2. Relevant equations 3. The attempt at a solution Firstly, I know that structure 4 is wrong (does not involve hydrogen). A quick glance at my textbook shows that the amino acid with the configuration of -OH shown in structure 3 does not exist, eliminating 3. However, I am stuck at 1 & 2 as they seem both correct. Any insight would be greatly appreciated.