A thermodynamic analysis of the binding interaction between polysorbate 20 and 80 with human serum albumins and immunoglobulins: A contribution to understand colloidal protein stabilisation

The results show that binding of the two detergents to human serum albumin is observed with binding constants of approximately ≈ 103 M− 1, with 1-3 detergent molecules binding to the albumins. The exact polysorbate-albumin ratio depends on the used albumin fraction. The interaction of the detergent is also obvious from the DSC results, showing an increase of the denaturation temperature. However, the binding of the detergent to the three investigated immunoglobulins is quite low and negligible, thus showing that for immunoglobulins a direct and strong polysorbate binding to the protein is not the reason for the colloidal stabilisation effect of immunoglobulins in solution in the presence of polysorbate 20 or 80.