Chemical Modification of Essential Histidine Residues in Mn(III)-Acid Phosphatase by Diethylpyrocarbonate in the Presence of F^- Ion(Biological)

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Mn(III)-acid phosphatase [EC 3.1.3,2] from sweet potato was inactivated by diethylpyrocarbonate (DEPC) in the presence of the F^- ion. Upon treatment of the inactivated enzyme with NH_2OH, the enzyme activity was significantly restored. The difference absorption spectra of the modified vs. native enzyme preparations, both in the presence and absence of the F^- ion, exhibited two prominent peaks at around 242 and 275nm. The pH-dependence of the inactivation rate suggested that an amino acid residue having a pK value of approximately 7.3 was involved in the inactivation. These results indicate that the inactivation was due to the modification of histidine residues. The correlation between the spectral change at 242 nm and the activity change of the enzyme in the presence and absence of the F^- ion revealed that 1 histidine residue per subunit was essential for the enzyme activity. The inactivation by DEPC occurred only in the presence of the F^- ion, which has been found to interact with the Mn in the active site, suggesting that the histidine residue to be modified is located at the active site of the enzyme.
社団法人日本薬学会の論文
1987-05-25