The structure of the unliganded form of the Escherichia coli cytoplasmic
peptidyl-prolyl isomerase (ppiB gene product) in a new crystal form was
determined by the molecular replacement method and refined to an R-factor of
16.1% at 2.1 A resolution. The enzyme crystallized in the orthorhombic C2221
space group with unit cell dimensions of a=44.7 A, b=68.2 A and c=102.0 A.
Comparison with the reported structure of the enzyme complexed with the
tripeptide substrate succinyl-Ala-Pro-Ala-p-nitroanilide revealed subtle changes
that occur upon complex formation. There is evidence to suggest that two surface
loops have significantly reduced mobility in the complexed structure.
Figure 3. (a) Stereo MOLSCRIPT [Kraulis 1991] schematic of
EcoCyPA with loops and secondary structural elements labelled
and (b) an orthogonal view showing the hydrophobic binding
Figure 5. Stereo view of the superimposed C^α traces for E.
coli cytoplasmic EcoCyPA (black) with (a) periplasmic EcoCyPB
(cyan) and (b) EcoCyPA complexed to a tripeptide substrate
The above figures are
by permission from Elsevier:
J Mol Biol