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Figure 2.
The SmTGR crystal structure in complex with gold ions (in
green) is superimposed to the mouse TR with NADPH bound (in
magenta; Protein Data Bank code 1zdl (30)). The root mean square
deviation is 0.82 Å over the 462 aligned residues. The
residues surrounding NADPH in mouse TR are conserved in SmTGR
(sequence alignment not shown). The structural comparison shows
the change in conformation of the loop 293–296 and in
particular of Tyr^296 and Ser^295, highlighted for the two
enzymes as balls and sticks (the other amino acid side chains
are omitted for clarity). The OG atom of Ser^295 is the closest
contact with the gold ion in the SmTGR crystal structure (see
“Results” and Fig. 1). In the mouse TR structure, Ser^295
shifts in position to make room for the bound NADPH; the clash
between the metal in site 3 and the phosphate of the cofactor in
SmTGR is self-evident.
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