Evidence of a strong interaction of 2,4-dichlorophenoxyacetic acid herbicide with human serum albumin

S.B. ROSSO; M. GONZALEZ; LUIS A. BAGATOLLI; R.O. DUFFAURD; GERARDO D. FIDELIO

LIFE SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 1998 vol. 63 p. 2343 - 2343

0024-3205

he interaction of 2,4-dichlorophenoxyacetic acid herbicide (2,4-D) with human serum albumin (HSA) was studied using fluorescence and differential scanning calorimetry (DSC). Fluorescence displacement of 1-anilino-8-naphtalenesulfonate (ANS) bound to HSA was used to evaluate the binding affinity of 2,4-D to HSA. The binding is associated to a high affinity site of HSA located in the IIIA subdomain. The association constant (Kass) of the herbicide was about 5 microM(-1), several times higher than the affinity found for pharmaceutical compounds. This relatively strong interaction with HSA was evidenced by the increase in HSA protein thermostability induced as consequence of herbicide interaction. 2,4-D induces an increase in the midpoint of thermal denaturation temperature from 60.1 degrees C in herbicide free solution to 75.6 degrees C in full ligand saturating condition. The calorimetric enthalpy and the excess heat capacity also increased upon 2,4-D binding. To investigate the possibi