FIG 4.

wY132A dimers have different features. 2F_o − F_c (where F_o and F_c are the observed and calculated structure factor amplitudes, respectively) electron density map of the wY132A crystal structure at 1.5-σ contour level with Cα chains and a subunit comparison among asymmetric units. The A subunit is shown in blue, the B subunit is in cyan, the C subunit is in orange, and the D subunit is in purple. The side view (a) and top view (b) of the AB dimer show that electron density covers the entire backbone. In comparison to views of the AB dimer, the side view (c) and top view (d) of the CD dimer show missing electron density at the loop, from residue 126 to 136, where dimers make contacts during assembly.