Mechanistic insight into interaction of Sodium Dodecyl Sulphate to asialylated form of glycoprotein: A mimic of membrane protein-lipid system.

The SDS-glycoprotein system is mimic of membrane protein-lipid system. Fate of glycoprotein, conformation and the interactive forces involved in membrane milieu are expected to be decided by the net charge on glycoprotein that may change during acidic environment in a range of pathological states, including cancer, stroke, and ischemia. Asialofetuin (ASF; asialylated form of glycoprotein) and SDS interaction is studied when glycoprotein bears varying range of net charge (i.e. at different pH's) by steady state and time-resolved spectroscopic, calorimetric and microscopic approaches. SDS interacts differently with ASF when protein is in cationic (at pH 2, 3 and 4) and in anionic states (pH 7.4). ASF undergo aggregation at pH 2, 3 and 4 whereas have enhancement in α-helical structure at pH 7.4 at sub-micellar concentrations of SDS. At pH 2, 3 and 4, the positively charged ASF interacts electrostatically with negatively charged head groups of SDS, leaving its hydrophobic tail free to interact with other protein-SDS complex and consequently lead to amyloid formation. However, at pH 7.4, the ASF interacts hydrophobically with SDS and an increase in α-helical content occurs that constrains the environment of Trp51 and consequently decreases movement of Trp conformers.