Hydrophobic behavior, ROS production, and heme degradation of hemoglobin upon interaction with n-alkyl sulfates

Abstract

The oxygen-containing free radical species form upon interaction of amphiphilic substances such as sodium dodecyl sulfate and hemoglobin. Under these conditions, hemoglobin is converted to methemoglobin and simultaneously results in heme degradation. Since heme is located in a hydrophobic moiety of hemoglobin, we hypothesized that other hydrophobic substances or amphiphilic xenobiotics can dispose hemoglobin to oxidative stress. Here this hypothesis was tested by investigating heme degradation of hemoglobin during interaction with n-alkyl sulfates. This was accomplished using UV–Vis and fluorescence spectroscopy, chemometric analysis, and chemiluminescence methods. We determined whether a relationship exists between the alkyl tail length (surfactant hydrophobicity) of n-alkyl sulfate homologues, reactive oxygen species (ROS) production, and heme degradation pattern of hemoglobin. We also proposed a mechanism for these types of interactions and induction of heme degradation. Our results indicated that hemoglobin structural–functional changes including globin denaturation are the key factors in starting the heme degradation process, and heme degradation product patterns were dependent on each alkyl sulfate. However, the number of fluorescent components (heme degradation products) was independent of the alkyl sulfate type. The reason for this phenomenon was the mechanism of reaction in which the amount of hydrogen peroxide was changed with each homologue, but the mechanism of degradation remained the same. Thus, an increase in hydrophobic chain length of the surfactants correlated with the enhanced ROS production and heme degradation of hemoglobin.