Selected positions of acyl chains are affected differently by antibody binding which results in decreased membrane fluidity

AbstractWe have studied the interaction between monoclonal anti-trinitrophenyl antibodies (IgGI and IgG2a) and haptenated phospholipid vesicles using stopped-flow fluorometry. Conformational changes of the antibodies were induced very rapidly (within 0.1 s) after binding to lipid haptens (TNP-Cap-DPPE) on the membrane surfaces. Conversely, after that, the bound antibody molecules decreased the degree of molecular motion at different depths m the bilayer, ranging from the polar head group to the terminal methyl groups of the fatty acyl chains. Such an effect reaches all places of the bilayer within 40 s at 25°C.Membrane fluidityStopped-flowLiposomeAntibody Lipid haptenExcimer fluorescenc