Immunological evidence for two types of PQQ-dependent d-glucose dehydrogenase in bacterial membranes and the location of the enzyme in Escherichia coli

Abstract Using an antibody raised against d -glucose dehydrogenase (EC 1.1.99.17) purified from Pseudomonas fluorescens , immuno-cross-reactivity with the enzymes from several bacterial strains and localization of the enzyme in Escherichia coli were examined. The antibody cross-reacted with glucose dehydrogenases from various Gram-negative bacteria examined. As a result, it became apparent that the enzymes from Gluconobacter, Acetobacter, Pseudomonas and Acinetobacter , which existed as holoenzymes in the membranes, had lower molecular weights than those from E. coli and Klebsiella , which were apoenzymes.
Treatment with trypsin of right-side out and inside-out membrane vesicles from E. coli clearly demonstrated that d -glucose dehydrogenase was located on the outer surface of the cytoplasmic membrane of E. coli , as had been suggested for Pseudomonas .