Differentiating the protein dynamics using fluorescence evolution of tryptophan residue(s): A comparative study of bovine and human serum albumins upon temperature jump

BSA contains two tryptophans, Trp-134 at surface regime and Trp-213 in hydrophobic fold, whereas HSA contains single tryptophan, Trp-214, analogous to Trp-213 in BSA. A fluorescent temperature jump apparatus was employed to illustrate the protein dynamics of BSA and HSA on millisecond timescale below their denaturing temperatures. Upon an instantaneous T-jump of 4.5 °C, the fluorescence intensity evolution of HSA is almost identical to that of dissolved tryptophan, indicating a temperature response. However, the fluorescence intensity change evolutions of BSA gradually differs from that of dissolved tryptophan at higher initial temperatures, strongly suggesting the protein dynamics at vicinity of Trp-134.