Abstract
Fluorescence quenching data on interaction of a fungicide methyl thiophanate (MT) with human serum albumin (HSA) elucidated a primary binding site at sub-domain IIA. Stern–Volmer algorithm and double log plot revealed the binding affinity (
K
a) and capacity (
n) of HSA as 1.65
×
10
4
M
−1 and 1.0 (
r
2
=
0.99), respectively. Cyclic voltammetric and circular dichroism (CD) studies reaffirmed MT–HSA binding and demonstrated reduction in α-helical content of HSA. Substantial release of the carbonyl and acid-soluble amino groups from MT treated HSA suggested protein damage. The plausible mechanism of methyl (
+CH
3) group transfer from MT to side chain NH group of tryptophan and HSA degradation elucidates the toxicological and clinical implications of this fungicide.