Biology Reference
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Figure 4.2 Structural overlays of Cgb. Overlays of the Cgb backbone with Vgb from
Vitreoscilla stercoraria (PDB id¼1VHB;
Tarricone et al., 1997
) (A), spermwhale myoglobin
(PDB id¼2JHO;
Arcovito et al., 2007
) (B), and the N-terminal domain of Hmp from E. coli
(PDB id¼1GVH;
Ilari, Bonamore, Farina, Johnson, & Boffi, 2002
) (C).
Figure 4.3 The haem-binding cleft of Cgb (PDB id¼2WY4;
Shepherd et al., 2010
), sperm
whale myoglobin (PDB id¼2JHO;
Arcovito et al., 2007
) and yeast cytochrome c perox-
idase (PDB id¼2PCC;
Pelletier & Kraut, 1992
). Structures contain either a cyanide or
sulphenate ion in the distal pocket. Only side chains that interact with the proximal
or distal ligands are shown.
stabilises the haem-bound dioxygen by H-bonding to it (
Fig. 4.3
), whereas
the B10 position is typically occupied by hydrophobic residues. In contrast
to mammalian globins such as Mb, the distal residues of peroxidases and oxi-
dases are much more polar, for example, the B10 and E7 residues in Cgb (an
NOD) are occupied by tyrosine and glutamine (
Fig. 4.3
A and B), and the
GlnE7 residue is
further
stabilised by a hydrogen-bonding network