The interaction of bacterial endotoxins (LPS Re and lipid A, the 'endotoxic principle' of LPS) with the endogenous antibiotic lactoferrin (LF) was investigated using various physical techniques and biological assays. By applying Fourier-transform infrared (FTIR) spectroscopy, we find that LF binds to the phosphate group within the lipid A part and induces a rigidification of the acyl chains of LPS. The secondary structure of the protein - as monitored by the amide I band - is, however, not changed. Concomitant with the IR data, scanning calorimetric data indicate a sharpening of the acyl chain phase transition. From titration calorimetric and zeta potential data, saturation of LF binding to LPS was found to lie at a [LF]:[LPS] ratio of 1:3 to 1:5 M from the former and 1:10 M from the latter technique. X-ray scattering data indicate a change of the lipid A aggregate structure from inverted cubic to multilamellar, and with fluorescence (FRET) spectroscopy, LF is shown to intercalate by itself into phospholipid liposomes and may also block the lipopolysaccharide-binding protein (LBP)-induced intercalation of LPS. The LPS-induced cytokine production of human mononuclear cells exhibits a decrease due to LF binding, whereas the coagulation of amebocyte lysate in the Limulus test exhibited concentration-dependent changes. Based on these results, a model for the mechanisms of endotoxin inactivation by LF is proposed.

The exudate of germinated spores of B. cereus IFO 13597 in 0.15 M KCl-50 mM potassium phosphate (pH 7.0) contained a spore-lytic enzyme which has substrate specificity for fragmented spore cortex from wild-type organisms (cortical-fragment-lytic enzyme [CFLE]), in addition to a previously characterized germinationspecific hydrolase which acts on intact spore cortex (spore cortex-lytic enzyme [SCLE]) (R. Moriyama, S. Kudoh, S. Miyata, S. Nonobe, A. Hattori, and S. Makino, J. Bacteriol. 178:5330-5332, 1996). CFLE was not capable of degrading isolated cortical fragments from spores of Bacillus subtilis ADD1, which lacks muramic acid ␦-lactam. This suggests that CFLE cooperates with SCLE in cortex hydrolysis during germination. CFLE was purified in an active form and identified as a 48-kDa protein which functions as an N-acetylglucosaminidase. Immunochemical studies suggested that the mature enzyme is localized on a rather peripheral region of the dormant spore, probably the exterior of the cortex layer. A gene encoding the enzyme, sleL, was cloned in Escherichia coli, and the nucleotide sequence was determined. The gene encodes a protein of 430 amino acids with a deduced molecular weight of 48,136. The N-terminal region contains a repeated motif common to several peptidoglycan binding proteins. Inspection of the data banks showed no similarity of CFLE with N-acetylglucosaminidases found so far, suggesting that CFLE is a novel type of N-acetylglucosaminidase. The B. subtilis genome sequence contains genes, yaaH and ydhD, which encode putative proteins showing similarity to SleL.The bacterial endospore cortex is responsible for the maintenance of spore dormancy and heat resistance. The cortex peptidoglycan has a unique spore-specific structure which allows it to fulfill its role, and cortex hydrolysis during spore germination is essential to allow spore outgrowth and the formation of a new vegetative cell (9, 21). The enzymes involved in these hydrolytic reactions have been identified from spores of several species.A germination-specific cortex-lytic enzyme (GSLE) from Bacillus megaterium spores (8) and a spore cortex-lytic enzyme (SCLE) from Bacillus cereus spores (16, 24), a mature form of SleB, were shown to hydrolyze intact spore peptidoglycan. A counterpart of B. cereus SCLE was also found to exist in Bacillus subtilis spores (23), though attempts to solubilize it were unsuccessful. The B. subtilis SCLE was involved in the response of spores to L-alanine-stimulated germination, and spores lacking this enzyme were unable to complete germination but showed limited cortex degradation (23). This suggests the contribution of a cortex-lytic enzyme(s) in addition to SCLE in the germination of B. cereus and B. subtilis spores. Indeed, analysis of muropeptide dynamics during germination of B. megaterium and B. subtilis spores unequivocally revealed that multiple enzymes are implicated in cortex degradation (2, 4). In Clostridium perfringens S40 spores, a cortical fragment-lytic enzyme (CFLE) which attacks disrupted corte...

The present study describes a synthesis of QD-lectin conjugates and their application for identification of leukaemia cells from normal lymphocytes using fluorescent confocal microscopy and flow cytometry. The results are compared with commercially available FITC-lectin.

We introduced a novel method for the rapid synthesis of silver nanohexagonal thin columns from an aqueous mixture of sodium thiosulfate (Na2S2O3) and silver chloride (AgCl) simply added to a phosphor bronze substrate. The reaction is based on galvanic displacement and the products are potentially useful for plasmonic applications.

Sepsis, a life-threatening syndrome with increasing incidence worldwide, is triggered by an overwhelming inflammation induced by microbial toxins released into the bloodstream during infection. A well-known sepsis-inducing factor is the membrane constituent of Gram-negative bacteria, lipopolysaccharide (LPS), signalling via Toll-like receptor-4. Although sepsis is caused in more than 50% cases by Gram-positive and mycoplasma cells, the causative compounds are still poorly described. In contradicting investigations lipoproteins/-peptides (LP), lipoteichoic acids (LTA), and peptidoglycans (PGN), were made responsible for eliciting this pathology. Here, we used human mononuclear cells from healthy donors to determine the cytokine-inducing activity of various LPs from different bacterial origin, synthetic and natural, and compared their activity with that of natural LTA and PGN. We demonstrate that LP are the most potent non-LPS pro-inflammatory toxins of the bacterial cell walls, signalling via Toll-like receptor-2, not only in vitro, but also when inoculated into mice: A synthetic LP caused sepsis-related pathological symptoms in a dose-response manner. Additionally, these mice produced pro-inflammatory cytokines characteristic of a septic reaction. Importantly, the recently designed polypeptide Aspidasept® which has been proven to efficiently neutralize LPS in vivo, inhibited cytokines induced by the various non-LPS compounds protecting animals from the pro-inflammatory activity of synthetic LP.