Comparative studies of interactions of hemoglobin with single-chain and with gemini surfactants

The interactions of hemoglobin with glutamic acid-based gemini surfactants (L2G2Cn) and with n-dodecylammonium α-glutamate (GDA) have been studied with isothermal titration microcalorimetry, fluorescence spectroscopy, UV–vis spectroscopy, and circular dichroism. The results indicate that GDA monomer can make the hemoglobin denatured, and that when the concentration of GDA is higher than cmc, heme monomer is released from the hydrophobic cavity of hemoglobin. On the other hand, L2G2Cn surfactants can also interact with hemoglobin. Compared with GDA, L2G2Cn have a much smaller binding ability with hemoglobin, and the circular dichroism spectra results show that the secondary structure of hemoglobin is possibly stabilized by a small amount of L2G2Cn, which may generate hydrophobic linkages between the nonpolar residues of hemoglobin. However, with further addition of L2G2Cn, the secondary structure of hemoglobin is unfolded, and the percentage of α helix in hemoglobin molecule is decreased. In addition, the L2G2Cn surfactant with a longer spacer can reduce the denaturing degree of hemoglobin.

The interactions of hemoglobin with glutamic acid-based gemini surfactants and with n-dodecylammonium α-glutamate (GDA) were studied. The interactions between the protein and the surfactants with different structures and the mechanism of these interactions were illuminated.Figure optionsDownload as PowerPoint slide