Figure 2: Superimposition of SHMT internal and external aldimine structures. Active site structures of B. stearothermophilus SHMT (internal aldimine form: PDB ID 1kkj) and B. stearothermophilus SHMT in complex with glycine and 5-formyl-H4PteGlu (PDB ID 1kl2) are displayed as yellow and cyan sticks, respectively. The 5-formyl-H4PteGlu molecule (FTHF) is displayed as magenta sticks. Side chains from the other subunits are rendered as brown sticks, and the corresponding labels are marked with asterisks. The picture was generated using PyMOL.