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Figure 4.
FIG. 4. Interaction mapping in enzyme-substrate (A), and
enzyme-product complexes (B). Interactions are shown only for
the phosphate chain moiety of the ligand. Due to the close
similarity of the nucleotide interactions in the three
enzyme-substrate complexes determined in the present study (cf.
Fig. 3 and Table I), the map was selected to show the actual
distances as found in the wild type dUTPase:  ,  -imino-dUTP: Mg2+ (X =
N) complex where W[cat] is also present. In the Asp90  Asn
mutant dUTPase: , -imino-dUTP:Mg2+ (X = N)
and Asp90 Asn mutant dUTPase:dUTP:
Mg2+ (X = O) complex, the only significant differences are that
(i) W[cat] is absent and Asp90O  2 becomes AsnN 2 and
(ii) in the Asp90 Asn mutant dUTPase:dUTP:
Mg2+ (X = O) complex, the X-Ser72O  interaction is absent.
Changes in all other distances are within ±0.2 Å.
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