SP127, a bacterial protein enhancing the activity of macrolide antibiotics against Pseudomonas aeruginosa: isolation and characterization.

Some strains belonging to the genera Bacillus and Pseudomonas were found to produce in the culture broth, a protein which synergistically enhanced the activity of macrolide antibiotics against Pseudomonas aeroginosa. The protein produced by Bacillus brevis ATCC 8185, designated SP127, was isolated in a pure state by means of ammonium sulfate fractionation, CM-cellulose column chromatography and gel filtration on Sephadex G-100. The sedimentation coefficient and the molecular weight of SP127 were 1.8 s and 15,000, respectively according to the analytical ultracentrifuge. The isoelectric point of SP127, obtained by electrofocusing experiments, was over 10.0. Half cystine and histidine were absent in the molecule.