Structural studies endotoxins

The 4-S Phosphate of KDO has been prepared from the 5-0-benzyl ether (Vol.l4, p.l31) via a 7,8-O-isopropylidene derivative, and its chemical stability was investigated in connection with structural studies on endotoxins, ... 

Synthetic Studies on Structural Elements of the Hydrophobic Region Present in Bacterial Endotoxins... 

The toxicity of polycarboxylic acid polymers is more sensitive to polymer structure and molecular weight than antitumor activity. The acute toxicity is markedly decreased with decreasing molecular weight (Table VI and XI). Further,polyanion polymers have been shown to highly sensitize mice to bacterial endotoxin (39)> this activity is strikingly molecular weight dependent as shown in Tables VII and XI as well as dose dependent ( 3. The enhanced sensitivity to endotoxin by synthetic anionic polymers has been extensively studied, but the mechanism of action is still not understood (39)-... 

Structural and functional studies of a synthetic peptide that mimics a proposed membrane inserting segment of a Bacillus thuringiensis delta-endotoxin have been conducted. An NMR study of a methanol solution of a synthetic 31-mer peptide corresponding to the sequence of a putative pore-forming segment of the CrylA(c) toxin showed that the peptide exists as an a-helix. Hie peptide forms discrete, characterizable channels in planar lipid bilayers. It is possible that this helix is a component of the transmembrane pore formed by Bacillus thuringiensis delta-endotoxins in vivo. 

More recently, other applications of CSLM in the characterization of membrane processes have been reported, such as the studies of Hayama et al. [26, 27] who visualized the distribution of an endotoxin trapped in an endotoxin-blocking filtration dialysis membrane. In their first study [26], they found that endotoxins were practically rejected by the outer skin layer of a polyester-polymer alloy (PEPA) membrane, hence playing a vital role in endotoxin removal from the dialysate fluid. In a second work [27], CSLM contributed successfully to visualize the distribution of endotoxin fiuorescently labeled in six kinds of dialysis membranes. They concluded that a dialysis membrane favorable for endotoxin blocking should have a double skin layer structure, composed of a hydrophilic inner skin layer and a completely hydrophobic void and outer skin layers. 

Nunez-Valdez, M.-E., J. Sanchez, L. Lina, L. Guereca, and A. Bravo. 2001. Structural and functional studies of a-helix 5 region from Bacillus thruingiensis CrylAb 5-endotoxins. Biochim. Biophys. Acta 1546 122-133. 

---