Probing the Interaction of Newly Synthesized Pt(II) Complex on Human Serum Albumin Using Competitive Binding Site Markers.

Abstract

Considering the importance of pharmacology and the influence of drugs on biological materials, the effects of a newly designed and synthesized platin complex (2,2'-Bipyridine-3,3'-dicarboxylic acid, oxalato Platinum(II), as an antitumor drug was tested on the structure of blood carrier protein of human serum albumin (HSA) using various spectroscopic techniques including UV-visible, fluorescence, and circular dichroism at 25 and 37°C. Results of the fluorescence measurements revealed that adding the complex caused reduction in intrinsic fluorescence emission of HSA resulted from dynamic quenching of HSA. The number of binding sites and binding constants were calculated at both temperatures of 25 and 37°C. In addition, in order to identify the complex's binding site on HSA employing spectroscopy, the competitive studies were followed using warfarin, digitoxin and ibuprofen as site markers of Sudlow sites I, II and III. Competitive binding test results have shown that Pt(II) complex bind on the warfarin binding site (or Sudlow sites I) on HSA. Besides, a reduction in thermal stability for HSA was observed in the presence of the newly designed Pt(II) complex.