Construction and characterization of a chimeric Escherichia coli PQQ glucose dehydrogenase (PQQGDH) with increased EDTA tolerance

The enzymatic characteristics of Escherichia coli pyrroloquinoline quinone glucose dehydrogenase (PQQGDH) was completely altered by substituting its partial sequence with corresponding Acinetobacter calcoaceticus PQQGDH region. A chimeric E. coli PQQGDH, E45A14E41 (45% of the N-terminal region and 41% of the C-terminal region were made of E. coli PQQGDH and the 14% remainder of A. calcoaceticus PQQGDH), was constructed by substituting with a region responsible for EDTA tolerance in A. calcoaceticus PQQGDH. Although E. call PQQGDH is easily inactivated in the presence of EDTA, the constructed chimeric enzyme, E45A14E41 showed significant increase in EDTA tolerance. in addition, the bivalent metal specificity for holo enzyme formation of E45A14E41 was completely different from that of E. coli PQQGDH.