Interaction between lipopolysaccharide and detergents detected by differential scanning calorimetry

The Gram-negative bacteria can cause very serious diseases. One of their pa thogenetic factors is the endotoxic lipopolysaccharide (LPS). This molecule is a component of outer membrane of Gram-negative bacteria. The LPS is rel eased from the living bacteria in a modest measure, but after killing off b acteria by antibiotics a larger quantity of endotoxin is released into the surrounding, This molecule can induce different biological effects includin g pyogenicity and toxic shock. The LPS is an amphiphilic molecule: it has a hydrophobic and a hydrophilic part of molecule, In water, the LPS can aggr egate. This aggregation process has been followed in our experiment by calo rimetry. When we mixed the LPS extracted from Shigella sonnei Re 4350 with different detergents (polymyxin B (PmB), deoxicholat (DOC)) in different co ncentration, we could diminish the measure of aggregation. The heat treatme nt process was reversible within the temperature range and detergent concen tration used by us. (C) 2001 Elsevier Science B.V. All rights reserved.