Evaluation of Measuring Methods of Human Serum Albumin-Drug Binding Affinity

This study evaluated the feasibility of measuring HSA-drug binding affinity by ordinary (free solution) method. NMR is used to identify where a drug binds. An HSA-immobilized column and mimic ion-exchange columns were developed to measure HSA-drug binding affinity. The correlation between capacity ratios (log k) measured using these columns and HSA-drug binding affinity (log nK) was not perfect. The log k values measured using the mimic ion-exchangers well correlated with log nK values measured by a modified Hummer-Dreyer method with purified HSA. The log k (log KHSA) of basic drugs correlated well with the log nK values measured by the modified Hummer-Dreyer method, but not for the acidic drugs. Simple measurement as the percent concentration of bound drug is another matter. Computational chemical prediction methods were proposed. One uses the molecular properties of drugs. Another involves the direct calculation of binding energy required using model phases. Further study is necessary to develop quick measurement and prediction method to accelerate the drug discovery process.