Hydrophobic interaction of four bile salts with hemoglobin induces unfolding of protein and evades protein degeneration induced by urea

Abstract

The interaction mechanism between natural bile salts (NaDC, NaTDC, NaC, and NaTC) and HB in vitro is presented using multi-spectrum methods (UV–vis, CD, DLS, and Fluorescence Spectroscopy), surface tension, bacteriostatic test, molecular docking, and molecular dynamics. The conformational change of HB was examined and mediated by different bile salt at pH 7.4 and at 298.2 K, which was significantly related to the interacting intensity. The bile salts were inserted into the hydrophobic cavity of HB. Hydrophobic interactions between the bile salt and HB induced protein unfolding, and the interacting intensity and extent of unfolding sequence were as follows, NaTDC > NaDC > NaTC > NaC. Bile salts' presence restricted hydrogen bonding between HB and urea, and thus prevented HB degeneration towards urea to a certain extent. Furthermore, a direct correlation was determined between the structure of the bile salt and the antibacterial effect. –OH groups in the steroidal skeleton and –CONH(CH2)2SO3Na were unfavorable for the antibacterial effect, hence, NaDC had the best antibacterial effect, followed by NaTDC.