Laboratory animals (the California rabbit) were immunized with natural preparations of Saccharomyces cerevisiae and Candida krusei yeasts. The resulting sera have been analyzed with ligand libraries constructed from synthetic oligosaccharides related to the main carbohydrate components of the fungal cell wall. It is shown that the antibodies in the studied sera predominantly recognize mannan fragments, with the carbohydrate specificity profile being different for S. cerevisiae and C. krusei. Sera against S. cerevisiae contained antibodies that recognize β-glucan, and the minimal recognizable epitope is linear trisaccharide. These results are necessary for the creation of needed immunoenzyme diagnostics for the detection and species characterization of fungi.

The carbohydrate specificity of antibodies obtained by immunizing laboratory animals with immunogens prepared from the Aspergillus fumigatus cell wall was analyzed using the library of biotinylated synthetic oligosaccharides. It has been shown that the main part of antipolysaccharide antibodies recognizes galactomannan in the studied immunogens with preference to its fragments containing more than two β-(1→5)-linked galactofuranosyl units. The data obtained can form the basis for the development of enzyme immunoassay for the detection of this dangerous fungal pathogen.

The electrospray ionization high-resolution mass spectra of biotinylated hexaethylene glycol–spacered molecular probes bearing biologically relevant carbohydrate moieties in positive and negative modes were recorded and interpreted. Collisionally induced decay mass spectra (positive mode) revealed different patterns depending on the charge of the parent ion, attached cations (or ions), the composition, and the sequence of carbohydrate fragments. The most intense peaks (two series) originated from the sequential cleavage of glycoside bonds resulting in charge location on the reducing end (Y series observed for all of the test compounds) or nonreducing end (B series). Hexaethylene glycol chain fragmentation giving rise to the cleavage of the C–O bond remote from the biotin moiety was observed. Other fragment ions lighter than the above by a difference of (C 2 H 4 O) n were absent or much smaller. Similar fragmentation was found for all of the nonsulfated biotinylated glycosides with the hexaethylene glycol spacer thus demonstrating that this type of fragmentation was characteristic of such molecular probes. Similar cleavages along with biotin moiety decay via the elimination of H 2 S and H 2 CS were observed for negative ions in the collisionally induced decay mass spectra of sulfated and neutral molecular probes.

An approach to estimate the degree of conjugation of oligosaccharide haptens to bovine serum albumin by the squarate procedure was proposed. The approach includes gel permeation HPLC in combination with the multichannel detection.

A spacer-armed pentasaccharide structurally related to a fragment of the mannan from the cell wall of the fungus Candida albicans and corresponding to the antigenic factor 6 has been synthesized. This compound, comprising two α-(1→2)- and three β-(1→2)-linked mannose residues, was prepared by glycosylation of a selectively protected α-(1→2)-dimannoside bearing an aglycone spacer and a free OH group at atom C(2´) with a β-(1→2)-trimannoside glycosyl donor. The successful synthesis evidences that large β-(1→2)-oligomannoside donor blocks can be used for the preparation of oligosaccharides including extended sequences of repeating β-(1→2)-linked mannose residues.

In the context of the project dealing with the synthesis and immunological study of the immunodominant fragments of the cell wall mannan in Candida albicans, the hexamannoside fragment corresponding to the antigenic factor 4 was assembled using the scheme [3+2+1]. The yield of the target hexasaccharide with the (α1→3)-glycosidic bond was higher than that obtained according to the previously used assembly scheme [2+2+2].

The 3-aminopropyl glycoside of a heptasaccharide fragment of the cell wall mannan from Candida guilliermondii 18, which corresponds to the antigenic Factor 9, has been synthesized by a convergent approach based on glycosylation of a tetrasaccharide acceptor with a trisaccharide donor as the key step to give a protected heptasaccharide 17. Subsequent two-step deprotection of 17 afforded the heptamannoside 18, which was then conjugated with BSA using the squarate procedure.