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Figure 6.
Figure 6. Orientation of the H-bonds in the  -sheet and
putative substrate binding site of different Parvulins. (A)
Arrangement of the G75-P76 cis amide bond in E. coli Par10,
compared with the two homologous structures hPin1 and hPar14. In
spite of the bulge resulting from the cis peptide bond, the -sheet of E.
coli Par10 can form all four H-bonds whereas the structures of
hPar14 and hPin1 with trans-Pro are only stabilized by three
H-bonds in this region (figure produced with Insight II, MSI
Inc.). (B) Comparison of the putative binding pockets of hPar14
(PDB code 1eq3, green residues) and hPin1 (PDB code 1pin; red
residues) overlaid on the E. coli Par10 structure (PDB code
1jnt; blue residues, grey backbone). The labeled residues are
highly conserved in all parvulins and may be involved in the
catalytic activity of these parvulins (figure produced with
MOLMOL, version 2k.1; Koradi et al. 1996). (C) Connolly surface
of E. coli Par10. Helix 4 (left) and the curved -sheet form a
lipophilic gap (brown), enabling a lipophilic oligopeptide
substrate to bind (figure produced with the MOLCAD module of the
program Sybyl, version 6.3; Tripos AG).
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