Kinetics of chlorotetracycline uptake in [formula omitted] by a fluorescence technique

• Published in: Biochemical and biophysical research communications Vol. 54; no. 2; pp. 790 - 795
• Main Authors: Dockter, Michael E., Magnuson, James A.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1973
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/0006-291X(73)91493-9

The antibiotic chlorotetracycline (CTC) is used as a fluorescent chelate probe to investigate the kinetics of its uptake into Staphylococcus aureus . CTC binds to divalent cations in an aqueous solution with enhanced fluorescence. This fluorescence is polarity dependent, being higher in apolar solutions. Upon addition of CTC to dispersions of S. aureus , a time dependent fluorescence enhancement is detected demonstrating that the CTC-divalent cation complex migrates into the apolar regions of the membrane. This uptake, which follows saturation kinetics, is energy dependent. A K m of 162 μ M was obtained for CTC concentration ranges of 0.2–100 μgm/ml.