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Figure 6.
Fig. 6. Cartoon of the proposed reaction schemes. Distortions
of the carboxyl, cyano, iodo, and azido groups play an important
role in the reaction catalyzed by ODCase. “P-Rib” indicates
ribose 5′-monophosphate. (a) The reaction from OMP to UMP
catalyzed by native ODCase. (b) Covalent-bond formation between
the mutant ODCase and 6-CN-UMP. (c) The conversion of 6-CN-UMP
to BMP catalyzed by native ODCase. (d) Covalent-bond formation
between the native ODCase and 6-I-UMP or 6-N[3]-UMP. (e) The
conversion of 6-I-UMP to BMP by K72A MtODCase. Distortion of the
bond linking the pyrimidine ring to the C6 substituent is
conserved in all these reactions, the physiologically relevant
decarboxylation and the nucleophilic mechanisms.
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