A recent example of the use of this technique was for studying the binding affinity of the protein membrane surrounding "Escherichia coli" to lipophilic cations used in drugs in various membrane mimetic environments. The motivation for the above study was that these membranes render the bacteria resistant to most compounds based on quaternary ammonium cation, which have the anti-bacterial effects. Thus an understanding of the binding phenomena would enable design of effective antibiotics for "E. coli". The researchers maintained a large excess of the ligand over the protein to allowing the binding reaction to go to completion. Using the above equations the researchers proceeded to calculate formula_13, formula_59, formula_60 and formula_61 for each drug in different environments. The data indicated that the binding stoichiometry of the drug with the membrane was 1:1 with a micromolar value of formula_13. The negative values of formula_59, formula_60 and formula_61 indicated that the process was enthalpy driven with a value of 8–12 kcal/mol for each drug.