Purification and characterization of macrolide 2'-phosphotransferase from a strain of Escherichia coli that is highly resistant to erythromycin.

Macrolide 2'-phosphotransferase [MPH(2')] was purified 90-fold from an erythromycin-resistant strain of Escherichia coli, and its enzymatic properties were investigated. MPH(2') is an inducible intracellular enzyme which showed high levels of activity with 14-member-ring macrolides and extremely low levels with 16-member-ring macrolides. The optimum pH for inactivation of oleandomycin was 8.2, and the optimum temperature of the reaction was 40 degrees C. Enzyme activity was lost by heat treatment at 50 degrees C for 1 min. The isoelectric point and molecular weight of the enzyme were 5.3 and 34,000, respectively. Purine nucleotides, such as GTP, ITP, and ATP, were effective as cofactors in the inactivation of macrolides. Iodine, EDTA, or divalent cations inhibited MPH(2') activity.