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Figure 1.
Figure 1 Schematic representation of glyoxalase I. (A) Monomer;
(B) dimer. The dimer has been colour ramped according to residue
number, starting with red at the N-terminus of one molecule,
passing through yellow at the C-terminus of that molecule and
finishing with blue at the C-terminus of the other monomer. The
zinc and its coordinating residues are shown in a ball and stick
representation with the zinc coloured green. The active site is
situated in a barrel which is formed only on dimerization.
Residue 114 is situated at the end of the red/yellow domain and
residue 123 at the beginning of the blue/green domain (see the
text). Prepared using MOLSCRIPT (Kraulis, 1991) modified by
R.Esnouf (Oxford University, unpublished). (C) A similar view of
the dihydroxybiphenyl dioxygenase (DHBD) enzyme (Han et al.,
1995) after superposition on the human glyoxalase I enzyme.
Again the molecule has been colour ramped according to residue
number, starting with red at the N-terminus and finishing with
blue at the C-terminus. Despite having only 14% sequence
identity (using the structures to align the sequences), 79 C
 pairs
from the C-terminal domains of this enzyme (blue and green) can
be aligned on glyoxalase I with an r.m.s.d. of 2 Å. The
colouring scheme clearly shows that the suggested domain
swapping in glyoxalase I is not present in DHBD. The ferrous
iron seen in DHBD is situated in a similar position to one of
the zincs in glyoxalase I. The residues coordinating the iron
are structurally equivalent to those binding the zinc.
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