PARAFAC study of bovine serum albumin conformational changes in the interaction with nanosized manganese oxide as a biomimetic model for water-oxidizing complex

Water splitting toward hydrogen production is an important step and a bottleneck for large-scale energy storage in artificial photosynthesis. The effect of metal oxide nanoparticles on the biopolymers behavior and their properties is important in designing new catalysts for water-splitting reaction. Herein, the interaction of bovine serum albumin (BSA) and MnOx nanoclusters is studied for the first time, exploiting the intrinsic excitation-emission (EEM) fluorescence of tryptophan and tyrosine residues. As the conformation of BSA changes as a function of pH and temperatures, three-way fluorescence data were recorded for BSA and BSA/MnOx. Then, the obtained profiles from parallel factor analysis (PARAFAC) were interpreted. Generally, the results from fluorescence spectroscopy showed that the MnOx nanoparticles cause some changes in the structure of BSA conformation as a function of pH and temperature. Also, the denaturation pathway of the BSA molecule is significantly different in the presence of MnOx nanoclusters. Moreover, the same result is acquired by augmentation of pH and temperature data for BSA and BSA/MnOx, which confirms that the fluorescence changes due to considered components during the processes. Although the EEM fluorescence spectra of similar proteins are almost identical, the cube of spectra measured during their conformational changes can be significantly different and applicable in rapid and low cost investigation of proteins. Spectral change and selectivity for similar proteins can be achieved without labeling with fluorophore molecules.