Practice question

Membrane protein purification requires disruption of lipid bilayer while preserving protein-protein and protein-cofactor interactions necessary for activity. Biological membranes are stabilized by hydrophobic interactions among fatty acyl chains and among transmembrane helices. Detergents are amphipathic molecules with hydrophilic head and hydrophobic tail that partition into bilayer, compete for hydrophobic surfaces, and at concentrations above critical micelle concentration form mixed micelles of lipid, detergent and protein. Appropriate non-ionic detergents like Triton X-100 and dodecyl maltoside surround hydrophobic transmembrane segments with detergent micelle shielding them from water, solubilizing protein into aqueous phase without necessarily denaturing. They disrupt lipid-protein and lipid-lipid hydrophobic interactions rather than covalent bonds, do not reinforce them nor stabilize native bilayer complex. Harsher ionic detergents like SDS unfold proteins exposing hydrophobic core. Careful detergent selection enables crystallization, enzymatic assay and interaction studies of membrane proteins essential for structural biology and drug discovery. Such detailed mechanistic insight is frequently examined in competitive tests including NEET, CUET, CSIR-NET and GATE where transporter classification, energetics and disease linkage are integrated into problem-solving questions.