Ribbon diagram of the crystal structures of the wild-type
protein and the GST50H mutant. The rainbow color-coding
represents the B value distribution of the backbone atoms of the
structures (blue = low B values, red = high B values). In the
crystal structures, the highest conformational flexibility is
observed in Helix B. The average B value for the main-chain
atoms of this structural segment averages to about B = 60 A^2
(see also Fig. 7 Figure 7-).
With the introduction of a histidine at position 50, the
mobility of this helix is dramatically increased by almost a
factor of 2 (see also Fig. 7 Figure 7-).
Despite this structural flexibility, the affinity of this mutant
to bind GSH has increased dramatically as well. The
corresponding density of the substrate was clearly visible in
the electron density maps and could be refined to full occupancy.
The above figure is reprinted
from an Open Access publication published by the Protein Society: