Inhibition of lectins

Fishman, C.W., Udey, M.C., Kurtz, M. and Wedner, J.J. (1981). Inhibition of lectin-induced lymphocyte activation by 2-cyclohexen-l-one decreased intracellular glutathione inhibits an early event in the activation sequence. J. Immunol. 127, 2257-2262. 

S. Andre, B. Liu, H.-J. Gabius, and R. Roy, First demonstration of differential inhibition of lectin binding by synthetic tri- and tetravalent glycoclusters from cross-coupling of rigidified 2-propynyl lactoside, Org. Biomol. Chem., 1 (2001) 3909-3916. 

The ability of saccharides to interact with the lectin was determined by their inhibition of lectin-induced agglutination of rabbit erythrocytes, according to the method of Smith ert al. (13). 

The importance of high valency in achieving good inhibition of lectin binding has been further investigated by the Consoli group [33, 34], who have focused on N-... 

Ko, H. L., Beuth, J., Solter, J., Schroten, H., Uhlenbruck, G., and Pulverer, G., 1987, In vitro and in vivo inhibition of lectin mediated adhesion of Pseudomonas aeruginosa by receptor blocking carbohydrates. Infection 15 237-240. 

Membrane extracts from adult H. contortus were enriched 24-fold for cysteine protease activity by passage over a Thiol-Sepharose affinity column and the proteins obtained (abbreviated as TSBP) were clearly localized to the microvillar surface of the intestinal cells (Knox et al., 1995,1999). TSBP comprised a prominent 60 kDa protein and several minor bands between 35 and 45 kDa and 97 to 120 kDa (Fig. 13.2). Protease activity at 38, 52 and 70 kDa was attributable to cysteine proteases and at 70 and 88 kDa to serine/metalloproteases, as judged by inhibition analyses. Lectin-binding studies showed that most of the TSBPs were glycosylated. Expression library... 

D. Page, D. Zanini, and R. Roy, Macromolecular recognition Effect of multivalency in the inhibition of binding of yeast mannan to concanavalin A and pea lectins by mannosylated dendrimers, Bioorg. Med. Chem., 4 (1996) 1949-1961. 

Thalhammer, A., Everts, I., and Hollmann, M. (2002) Inhibition by lectins of glutamate receptor desensitization is determined by the lectin s sugar specificity at kainate but not AMPA receptors. Mol. Cell. Neurosci. 21, 521-33. 

Figure 14.8 (A) Screening of a glycopeptide library using a fluorescent-labeled lectin and ligands bound to PEGA beads. The acbve compounds are analysed by mass spectrometry. (B) FITC-labeled lectin binding to resin bound mannose could be inhibited by soluble glycopeptides obtained from library screen. Percent inhibition was quantified by recording of lectin fluorescence. Only every second well of the microtiter plate was used and nonfluorescent beads indicated good inhibitors.44...

B17. Bussing, A., Vervecken, W, Wagner, M., Wagner, B., Pfuller, U., and Schietzel, M., Expression of mitochondrial Apo2.7 molecules and caspase-3 activation in human lymphocytes treated with the ribosome-inhibiting mistletoe lectins and the cell membrane permeabilizing viscotoxins. Cytometry 37, 133-139 (1999). 

To further exploit the potential usefiilness of this new family of clusters, monoadduct 54 was saponified into 55 (0.05 M NaOH, quant) and condensed to L-lysine methyl ester using 2-ethoxy-l-ethoxycarbonyl-l,2-dihydroquinoline (EEDQ) to give extended dimer 56 in 50 % yield together with monoadduct in 15 % yield [75]. Additionally, tert-butyl thioethers 52 could be transformed into thiols by a two step process involving 2-nitrobenzenesulfenyl chloride (2-N02-PhSCl, HOAc, r.t, 3h, 84%) followed by disulfide reduction with 2-mercaptoethanol (60%). Curiously, attempts to directly obtain these thiolated telomers by reaction with thioacetic acid f ed. These telomers were slightly better ligands then lactose in inhibition of binding of peanut lectin to a polymeric lactoside [76]. 

The ready availability of lectins, their ease of preparation in purified form, the fact that they are amenable to chemical manipulation and that many of them are inhibited by simple sugars, has made them a most attractive tool in biologic research. 

Figure 1. Inhibition by lectins of complement fixation by the anti-H-2A-lympho-cyte reaction. ( ) M. pomifera agglutinin (A) W. floribunda mitogen (O) con-canamlin A (9) W. floribunda agglutinin ( V) S. japonica agglutinin.

In order to determine if lectins affect the reactions of complement mediated hemolysis subsequent to binding of antibody to the lymphocyte we have employed a synthetic particulate antigen. This was accomplished by testing the ability of lectin to inhibit the fixation of complement by the complex of anti-human serum albumin (HSA) and HSA-conjugated aminoethyl Biogel beads. The HSA-conjugated aminoethyl Biogel beads may be considered to be cell-like particles coated with a carbohydrate-free protein. 

Thus, the anti-HSA immunoglobulin will be able to react with these particles, but lectins should be unreactive and not competitively interfere with the binding of antibody to the beads. Though the antibody-conjugated bead complex is capable of fixing complement, all the lectins utilized in this work cause no more than a 6% decrease in the fixation of complement, even at concentrations in excess of the amount of lectin needed to cause maximum inhibition of complement in the anti-H-2.4-lymphocyte reaction. 

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