In 2008, we published a paper describing the Conformational dynamics of members of the adenylate enzymes. The paper proposes the domain alternation hypothesis where the C-Terminal portion of the adenylate enzyme rotates by 140 degrees to allow multiple catalytic residues access to the active site pocket. Below is a morph generated between two crystal structures of CBAL( 3CW8, 3CW9) solved in the adenylate and thioester forming conformations respectively. The labile C-terminal is represented in green with active site residues in purple. The more stable N-terminal portion of the adenylate is depicted with a tan surface. This domain alternation has recently been shown to be very important in domain choreography associated with NRPS enzymes that are a prime source for antibiotics and other natural products.