Chemo-bacterial synthesis and immunoreactivity of a brain HNK-1 analogue.

This work reports the synthesis and the biological validation of a trisaccharide analogue of the HNK-1 epitope. The 3-O-sulfo-ß-d-GlcpA-(1→3)-ß-d-Galp-(1→4)-ß-d-Glcp-allyl has been prepared by enzymatic glucuronylation of allyl lactoside by an engineered recombinant Escherichia coli strain followed by a chemoselective sulfation. Subsequent covalent attachment of the ozone-oxidised trisaccharide to bovine serum albumin provided a neo-glycoconjugate, which has been interrogated with antibodies specific to the human natural killer carbohydrate epitope HNK-1. ELISA assays confirmed the absolute requirement of the sulfate group for protein recognition and the potential application of this synthetic oligosaccharide as HNK-1 surrogate.

Immunochemical detection of food-derived isothiocyanate as a lysine conjugate.

In a previous study we prepared monoclonal antibody against allyl isothiocyanate (AITC)-modified lysine (Lys), and found that AITC reacted with Lys under physiological conditions in vitro (T. Nakamura et al., Chem. Res. Toxicol., 22, 536-542 (2009)). In the present study, antibodies against benzyl isothiocyanate (ITC), 6-methylsulfinylhexyl ITC and phenethyl ITC modified protein were prepared, and the respective monoclonal antibodies, B6C9, 6MS3D10, and PE3A10 were obtained. These antibodies were applied to ITC detection in food using shredded Wasabia japonica (wasabi) and ground Carica papaya (papaya) seed by trapping ITC with biotin-labeled bovine serum albumin. ITC formation from the wasabi and papaya seed samples was confirmed using the antibodies in a dose-dependent manner. These antibodies might be applicable in identifying food-derived ITC.

Structures of the glycopeptidolipid antigens of serovars 25 and 26 of the Mycobacterium avium serocomplex, synthesis of allyl glycosides of the outer disaccharide units and serology of the derived neoglycoproteins.

The pentasaccharide hapten released from the glycopeptidolipid (GPL) antigen of M. avium serovar 26 has been characterized as O-(2,4-di-O-methyl-alpha-L-fucopyranosyl)-(1-->4)- O-beta-D-glucopyranosyluronic acid-(1-->4)-O-(2-O-methyl-alpha-L-fucopyranosyl)-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)-6-deoxy-L-talose. The allyl glycosides of the outer glycosyl and glycobiosyl units of this hapten have been synthesized, the latter by a route involving oxidation of the corresponding D-glucopyranose derivative. Conjugation of allyl glycosides to protein by ozonolysis and reductive coupling afforded neoantigens (neo 26-1 and 26-2), both of which interacted with antibodies to M. avium serovar 26. The terminal sugar residue of the pentasaccharide hapten of the serovar 25 GPL had been shown to have the galacto configuration on the basis of 1H-13C NMR correlation spectroscopy, but absolute configurational assignment for the sugar awaited the synthesis, as for neo 26, of two glycobiosyl NGPs bearing the terminal sugar in the D and L enantiomeric forms, respectively. Only the glycobiosyl NGP bearing the terminal sugar as the D-enantiomer interacted with antibodies to M. avium serovar 25, thus providing evidence for the absolute configuration of the sugar, and showing that the complete oligosaccharide hapten has the structure, O-(4-acetamido-4,6-dideoxy-2-O-methyl-alpha-D- galactopyranosyl)-(1-->4)-O-beta-D-glucopyranosyluronic acid-(1-->4)-O-(2-O-methyl-alpha-L-fucopyranosyl)-(1-->3)-O-alpha-L- rhamnopyranosyl-(1-->2)-6-deoxy-L-talose.

Affinity cytotoxicity with an alcohol dehydrogenase-antibody conjugate and allyl alcohol.

A potent new enzyme-antibody conjugate system for amplifying cytotoxicity was tested in a well-defined model of hapten [2,4,6-trinitrophenyl (TNP)]-substituted tumor cells (HEp2) and purified anti-hapten antibody. Brief treatment of TNP-HEp2 cells with low concentrations (0.05 to 0.74 micrograms/ml) of antihapten antibody-alcohol dehydrogenase conjugate (Ab-ADH) followed by culture in complement-free medium containing nicotinamide adenine dinucleotide and allyl alcohol or 2-fluoroethanol resulted in 15 to 90% cell killing as measured by 5-[125l]iodo'-2-deoxyuridine uptake assay. The importance of the complete enzyme system was indicated by reduced or absent cytotoxicity if Ab-ADH, nicotinamide adenine dinucleotide, or allyl alcohol (or 2-fluorethanol) were omitted. Immunological specificity of the Ab-ADH was demonstrated by reduced or absent cytotoxicity when: (a) HEp2 cells were not coated with TNP; (b) Ab-ADH binding onto TNP-cells was blocked by free hapten (2,4-dinitrophenyllysine); or (c) unconjugated alcohol dehydrogenase and anti-TNP purified IgG anti-2,4,6-trinitrophenyl antibody with NAD+ and allyl alcohol or anti-TNP antibody with complement were used.