| 總結: | Interaction of pendimethalin (PM) herbicide with human serum albumin (HSA) was
studied using fluorescence, circular dichroism (CD) and molecular modeling methods.
The attenuation of the fluorescence intensity of HSA in the presence of PM revealed
formation of the PM-HSA complex. Analysis of the fluorescence quenching data showed
moderately strong binding affinity between PM and HSA. Both hydrophobic interactions
and hydrogen bonds were suggested to stabilize the PM-HSA complex, based on
thermodynamic data. Binding of PM to HSA induced perturbation in the
microenvironment around the aromatic fluorophores as well as secondary and tertiary
structural changes in the protein. Complex formation between PM and HSA led to an
increase in its thermal stability. Both site marker displacement and molecular modeling
results suggested site I, located in subdomain IIA, as the preferred binding site of PM on
HSA. A comparative study on the interaction between PM and serum albumins of bovine
(BSA), sheep (SSA), porcine (PSA), human (HSA) and rabbit (RbSA) was also made
using fluorescence quenching titration and site marker displacement experiments. Similar
magnitude of PM-induced fluorescence quenching was observed with BSA and HSA,
compared to other albumins. The binding affinity of PM to these albumins was found to
follow the order: SSA > HSA > BSA > RbSA > PSA. Warfarin (WFN) displacement
results also suggested similar displacing action of PM on WFN-BSA and WFN-HSA
complexes. All these results suggested close similarity between BSA and HSA in terms
of PM binding characteristics.
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