Relationship between phosphate content and immunochemical properties of subfractions of bakers' yeast mannan

Presence of O-glycosidically linked oligosaccharides in the cell wall mannan of Candida krusei purified with Benanomicin A

Cell wall mannan of the pathogenic yeast Candida krusei was prepared using the antibiotic Benanomicin A, which has a lectin-like function. The chemical structure of this molecule was found to be similar to that of mannan prepared from the same yeast by the conventional method using Fehling reagent. Only a few degradation products were detected when the mannan prepared using Fehling reagent was subjected to alkali treatment (β-elimination), but multiple α-1,2-linked oligosaccharides were detected when the mannan purified with Benanomicin A was treated with alkali. These results indicate that most of the O-linked sugar chains in mannan were lost under conventional conditions when exposed to the strongly alkaline Fehling reagent. In contrast, the O-glycosidic bond in mannan was not cleaved and the O-linked sugar chains were maintained and almost intact following treatment with the mild novel preparation method using Benanomicin A. Therefore, we argue that the new mannan preparation method using Benanomicin A is superior to conventional methods. In addition, our study suggests that some yeast mannans, whose overall structure has already been reported, may contain more O-linked sugar chains than previously recognized.

Immunochemistry of pathogenic yeast, Candida species, focusing on mannan

This review describes recent findings based on structural and immunochemical analyses of the cell wall mannan of Candida albicans, and other medically important Candida species. Mannan has been shown to consist of α-1,2-, α-1,3-, α-1,6-, and β-1,2-linked mannopyranose units with few phosphate groups. Each Candida species has a unique mannan structure biosynthesized by sequential collaboration between species-specific mannosyltransferases. In particular, the β-1,2-linked mannose units have been shown to comprise a characteristic oligomannosyl side chain that is strongly antigenic. For these pathogenic Candida species, cell-surface mannan was also found to participate in the adhesion to the epithelial cells, recognition by innate immune receptors and development of pathogenicity. Therefore, clarification of the precise chemical structure of Candida mannan is indispensable for understanding the mechanism of pathogenicity, and for development of new antifungal drugs and immunotherapeutic procedures.

Production of anti-Candida antibodies in mice with gut colonization of Candida albicans

BACKGROUND: Production of antibodies that are specific for allergens is an important pathological process in inflammatory allergic diseases. These contain the antibodies against antigens of Candida albicans, one of the normal microbial flora in an intestinal tract. We studied the effects of the prednisolone administration on the production of anti-Candida antibodies in the gastrointestinally C. albicans-colonized mice. METHODS AND MATERIALS: BALB/c mice, treated with antibacterial antibiotics to decontaminate indigenous intestinal bacterial flora, were inoculated intragastrically with C. albicans. The mice, in which C. albicans grows intestinally, were administered prednisolone to induce temporary immunosuppression. The Candida growth in their intestinal tract and their antibody response to Candida were examined. RESULTS: Antibiotic treatment allowed establishment of C. albicans gastrointestinal colonization, but did not cause subsequent systemic dissemination of C. albicans in all the animals. When these animals received an additional treatment with prednisolone, they showed a significantly higher population of C. albicans in their feces than those of animals treated with antibiotics alone, and the organisms were recovered even from their kidney. This systemic dissemination by C. albicans appeared to be temporal, because all the mice survived without any symptoms for more than 2 months. Examination of the serum titers of total immunoglobulin (Ig)E antibodies and specific IgE and IgG antibodies against Candida antigens demonstrated that titers of total IgE increased, partially by day 14 and clearly at day 27, in prednisolone-treated Candida-colonized mice. Without prednisolone treatment, an increment of the serum titer was scarcely observed. By day 27, corresponding to the increase of total IgE, the anti-Candida IgE and IgG titer increased in mice of the prednisolone-treated group. CONCLUSION: Administration of prednisolone to Candida-colonized mice can induce production of the IgG, IgE antibodies against Candida antigens, perhaps through temporal systemic dissemination of Candida from the intestinal tract.

A possible mechanism for the exchange of transferrin-67Ga complex to heparan sulfate-67Ga complex

We attempted to identify the exchange mechanism of transferrin-67Ga complex to heparan sulfate-67Ga complex. The effect of phosphate on the binding ability of 67Ga to transferrin and heparan sulfate was studied by the dialysis method. The phosphate inhibited the binding ability of 67Ga to transferrin, while the phosphate enhanced the 67Ga binding ability to heparan sulfate. The results suggest that the phosphate is involved in the translocation of 67Ga from the transferrin to the heparan sulfate.

Structural modification of cell wall mannans of Candida albicans serotype A strains grown in yeast extract-Sabouraud liquid medium under acidic conditions

The cell wall mannans of two Candida albicans serotype A strains, NIH A-207 and J-1012 (abbreviated as A and J strains, respectively), cultured in yeast extract-Sabouraud liquid medium at pH 2.0, contained neither a phosphate group nor a beta-1,2-linked mannopyranose unit (H. Kobayashi, P. Giummelly, S. Takahashi, M. Ishida, J. Sato, M. Takaku, Y. Nishidate, N. Shibata, Y. Okawa, and S. Suzuki, Biochem. Biophys. Res. Commun. 175:1003-1009, 1991). In this study, the mannans obtained from A and J strains grown in pH 2.0 medium (abbreviated as mannans A2 and J2, respectively) exhibited quite different reactivities against rabbit anti-C. albicans and anti-Saccharomyces cerevisiae sera compared with those of mannans from the corresponding strains cultured in conventional medium at pH 5.9 (abbreviated as mannans A and J, respectively). Namely, mannans A2 and J2 lost reactivity against the former serum but reacted with the latter serum to a higher extent than mannans A and J. In order to account for these difference in more detail, mannans A2 and J2 were subjected to acetolysis. Elution profiles of the acetolysates were completely different from those of acetolysates obtained from mannans A and J reported in our previous papers. The 1H nuclear magnetic resonance spectra of the oligosaccharides from mannans A2 and J2 obtained by this procedure indicate that the side chains are composed of alpha-linked mannopyranose units densely linked to the alpha-1,6-linked backbone. The long side chains containing one alpha-1,3-linked mannopyranose unit are markedly increased.

Structural study of a cell-wall mannan of Saccharomyces kluyveri IFO 1685 strain. Presence of a branched side chain and beta-1,2-linkage

Acetolysis of the cell-wall mannan of Saccharomyces kluyveri under mild conditions, gave fragments with 1-6 mannose residues. The structures of mannopentaose and mannohexaose were determined to be [Formula; see text] respectively, by two-dimensional homonuclear Hartmann-Hahn spectroscopy and a sequential NMR assignment method that combines 1H-13C correlated spectroscopy, relayed coherence transfer spectroscopy, 1H-detected heteronuclear multiple-bond connectivity and methylation analysis. The H1 proton chemical shift of a neighboring alpha-1,2-linked mannose unit of the 3-O-substituted structure was shifted upfield by the addition of a mannose unit to the adjacent 3-O-substituted unit by an alpha-1,6 linkage. The characteristic H1--H2-correlated cross-peak of the alpha-1,3-linked mannose unit substituted by a beta-1,2 linkage, beta 1-->2Man alpha 1-->3, in the mannan of S. kluyveri, as also found by two-dimensional homonuclear Hartmann-Hahn spectroscopy in the mannan of Candida guilliermondii, a pathogenic yeast in man.

Structural identification of an epitope of antigenic factor 5 in mannans of Candida albicans NIH B-792 (serotype B) and J-1012 (serotype A) as beta-1,2-linked oligomannosyl residues

In previous articles, we reported the presence of phosphate-bound beta-1,2-linked oligomannosyl residues in the mannans of strains of Candida albicans serotypes A and B and Candida stellatoidea. To identify the antigenic factor corresponding to this type of oligomannosyl residue, a relationship between chemical structure and antigenic specificity in the mannans of C. albicans NIH B-792 (serotype B, B-strain) and C. albicans J-1012 (serotype A, J-strain) was investigated by using a combination of two-dimensional 1H nuclear magnetic resonance spectroscopy of H-1, H-2, and H-5 regions in the mannans and an enzyme-linked immunosorbent assay that employed concanavalin A-coated microtiter plates. It was shown in the present 1H nuclear magnetic resonance study that an examination of chemical shifts not only in the H-1 region but also in the H-5 region was useful for the quantitative determination of the phosphate-bound beta-1,2-linked oligomannosyl residues. In the enzyme-linked immunosorbent assay using concanavalin A-coated plates, it was revealed that, of factor sera 1, 4, and 5, only factor serum 5 showed a reactivity proportional to the densities of the beta-1,2-linked oligomannosyl residues of the mannan subfractions of different phosphate contents that had been prepared from the bulk B-strain mannan by DEAE-Sephadex chromatography. The above results indicate that the phosphate-bound beta-1,2-linked oligomannosyl residues, Manp beta 1----(2Manp beta 1----)n2Man (n = 0-5), correspond to antigenic factor 5.

Evaluation of an enzyme immunoassay using neoglycolipids constructed from Candida albicans oligomannosides to define the specificity of anti-mannan antibodies

In order to study the respective roles of oligomannoside sequences in the antigenicity of Candida albicans phosphopeptidomannan, a method was developed for constructing neoglycolipids from oligomannosides released by depolymerisation of this molecule. Oligomannosides released by acetolysis were converted to neoglycolipids by coupling them to 4-hexadecylaniline in an equimolar reaction checked by thin layer chromatography. When coated onto microEIA plates, the neoglycolipids exhibited strong reactions which were dose dependent and were saturable with concanavalin A. Reactivity of neoglycolipids with immunoglobulins were then tested with a panel of monoclonal and polyclonal antibodies reacting with epitopes present in the original phosphopeptidomannan. One of two IgM monoclonal antibodies and two of five monospecific rabbit polyclonal IgG reacted strongly with neoglycolipids therefore providing evidence of the presence of structures mimicking epitopes within the pool of neoglycolipids. When 38 sera from 18 hospital inpatients with various levels of antibodies to Candida albicans were tested, a correlation was observed between the EIA to detect neoglycolipids and the EIA to detect phosphopeptidomannan. Successive sera from all patients showing seroconversion in the immunofluorescence assay had increased EIA signals for neoglycolipids.

Presence of human antibodies reacting with Candida albicans O-linked oligomannosides revealed by using an enzyme-linked immunosorbent assay and neoglycolipids

In order to study the presence of antibodies directed against Candida albicans O-linked oligomannosides (oligomannosides O) in patient sera, we have developed an enzyme-linked immunosorbent assay (ELISA) involving neoglycolipids constructed with these residues (NGLO). Oligomannosides O released by mild alkaline degradation of the C. albicans cell wall phosphopeptidomannan (PPM) contained one to seven mannose residues, among which the quantitatively major components, mannobiose and mannotriose, were shown by 1H nuclear magnetic resonance to contain exclusively alpha (1-2) linkages. The pool of oligomannosides was converted to neoglycolipids by coupling them to 4-hexadecylaniline in an equimolar reaction checked by thin-layer chromatography. We have tested against these neoantigens, coated on ELISA plates, 15 pairs of sera corresponding to individual seroconversions observed in 15 patients during the course of a mycological and serological survey of candidiasis. For all patients, seroconversions resulted in an increased level of antibodies against NGLO. A significant correlation was observed between the results of ELISA-NGLO, ELISA involving the original PPM molecule, and routine antibody detection tests, indirect immunofluorescence assay, and cocounterimmunoelectrophoresis. These results therefore demonstrate the synthesis of human antibodies reactive with oligomannosides O constitutive of the C. albicans mannan molecule which have been previously described as exhibiting an inhibitory effect on human lymphocytic proliferation.

Structural study on a phosphorylated mannotetraose obtained from the phosphomannan of Candida albicans NIH B-792 strain by acetolysis

A mixture of phosphorylated manno-oligosaccharides was isolated from the acid-stable domain of phosphomannan of Candida albicans NIH B-792 strain (serotype B) by acetolysis and was fractionated on a column of Bio-Gel P-2 equilibrated with 50 mM pyridine-CH3COOH buffer, pH 5.0. A monophosphorylated mannotetraose was isolated as the major constituent. Structural analyses of this phosphate-containing tetraose and its reduction product with NaBH4 by 1H, 13C, and two-dimensional homonuclear Hartmann-Hahn NMR spectroscopies, subsequently, gave results consistent with the structure described below (where Manp represents the mannopyranose unit): [formula: see text] It was unexpected that the major phosphorylated branch in the acid-stable domain of the parent phosphomannan of this C. albicans strain is a relatively short mannotetraosyl residue containing solely alpha-1,2-linked mannopyranose units, and a phosphate group as a 6-O-ester on the intermediary unit adjacent to the nonreducing terminal group. These findings indicate that the size of the major phosphorylated branch of this phosphomannan is the same as that of Saccharomyces cerevisiae.

Immunoreactivity of neoglycolipids constructed from oligomannosidic residues of the Candida albicans cell wall

To establish a model to study the immunoreactivity of oligosaccharidic structures from the Candida albicans cell wall, we attempted to construct neoglycolipids with these residues by using oligomannosides released after mild acid hydrolysis of the phosphopeptidomannans isolated from yeast forms. From a mixture of manno-oligosaccharides ranging from mannobiose to mannononaose, the structure of a quantitatively major component (mannotriose) was determined to be Man (beta 1-2) Man (beta 1-2) Man alpha by 1H nuclear magnetic resonance analysis. After coupling of the pool of oligosaccharides to a lipid (4-hexadecylaniline), the synthesized molecules were injected into mice and rats. Antibody responses were detected on enzyme-linked immunosorbent assay plates coated with either phosphopeptidomannans or neoglycolipids. The hybrid molecules exhibited both immunogenicity and antigenicity. The kinetics of antibody responses as well as immunofluorescence patterns observed on whole C. albicans cells strongly mimicked results from the immunization of animals with natural antigens. Construction of neoglycolipids could therefore provide an interesting approach to the study of specific oligosaccharides of C. albicans and their recognition by the host immune system.

Structure of the D-mannan of Candida stellatoidea IFO 1397 strain. Comparison with that of the phospho-D-mannan of Candida albicans NIH B-792 strain

The structure of the D-mannan of Candida stellatoidea IFO 1397 strain, which has properties identical to those of the phospho-D-mannan of C. albicans serotype B strain, does not contain phosphate groups, and its 1H- and 13C-n.m.r. spectra are quite similar to those of the phospho-D-mannan of C. albicans NIH B-792 strain. However, the 1H-n.m.r. and 1H-13C-correlation n.m.r. spectra of the products obtained by digestion with alpha-D-mannosidase of C. stellatoidea D-mannan considerably differed from those of the corresponding digestion products of the C. albicans phospho-D-mannan. Additionally, the enzyme-linked immunosorbent assay, by means of a monoclonal antibody corresponding to (1----2)-linked beta-D-oligomannosyl residues, of the phospho-D-mannan of the same C. albicans strain indicated that the C. stellatoidea D-mannan does not contain any (1----2)-linked beta-D-oligomannosyl residues. The absence of these residues may be used as one of the criteria of chemotaxonomical identification of C. stellatoidea spp.

Structural study of cell wall phosphomannan of Candida albicans NIH B-792 (serotype B) strain, with special reference to 1H and 13C NMR analyses of acid-labile oligomannosyl residues

Chemical structures of manno-oligosaccharides, from biose to heptaose, released from the phosphomannan of Candida albicans NIH B-792 strain (serotype B) by mild acid hydrolysis were investigated. The results of 1H NMR, 13C NMR, and fast atom bombardment mass spectrometry analyses confirmed that these manno-oligosaccharides belong to a homologous beta-1,2-linked series. Although chemical shifts of 1H NMR patterns of these oligosaccharides were considerably too complicated to be assigned, their 13C NMR patterns were sufficiently simple to be interpreted, exhibiting a regular increase of downfield shift of ppm values of the C-1 atom from each mannopyranose residue in proportion to their molecular weights. In order to determine the whole chemical structure of the parent phosphomannan, the acid-stable domain was subjected to acetolysis and then enzymolysis with the Arthrobacter GJM-1 alpha-mannosidase and the resultant manno-oligosaccharides were investigated for their chemical structures by 1H NMR spectroscopy. The results of a precipitin-inhibition test using the beta-1,2-linked manno-oligosaccharides, from biose to hexaose, in comparison with the corresponding isomers containing alpha-1,2 linkage with small amounts of alpha-1,3 linkage, indicated that the haptens possessing the former linkage exhibited much higher inhibitory effects than the corresponding isomers containing the latter linkages did. Based on the present findings, a chemical structure of the phosphomannan of this C. albicans strain was proposed.

Structural study of phosphomannan of yeast-form cells of Candida albicans J-1012 strain with special reference to application of mild acetolysis

Structural analysis of the phosphomannan isolated from yeast-form cells of a pathogenic yeast, Candida albicans J-1012 strain, was conducted. Treatment of this phosphomannan (Fr. J) with 10 mM HCl at 100 degrees C for 60 min gave a mixture of beta-1,2-linked manno-oligosaccharides, from tetraose to biose plus mannose, and an acid-stable mannan moiety (Fr. J-a), which was then acetolyzed by means of an acetolysis medium, 100:100:1 (v/v) mixture of (CH3CO)2O, CH3COOH, and H2SO4, at 40 degrees C for 36 h in order to avoid cleavage of the beta-1,2 linkage. The resultant manno-oligosaccharide mixture was fractionated on a column of Bio-Gel P-2 to yield insufficiently resolved manno-oligosaccharide fractions higher than pentaose and lower manno-oligosaccharides ranging from tetraose to biose plus mannose. The higher manno-oligosaccharide fraction was then digested with the Arthrobacter GJM-1 alpha-mannosidase in order to cleave the enzyme-susceptible alpha-1,2 and alpha-1,3 linkages, leaving manno-oligosaccharides containing the beta-1,2 linkage at their nonreducing terminal sites, Manp beta 1----2Manp alpha 1----2Manp alpha 1----2Manp alpha 1----2Man, Manp beta 1----2Manp beta 1----2Manp alpha 1----2Manp alpha 1---- 2Manp alpha 1----2Man, and Manp beta 1----2Manp beta 1----2Manp beta 1----2Manp alpha 1---- 2Manp alpha 1----2Manp alpha 1----2Man. However, the result of acetolysis of Fr. J-a by means of a 10:10:1 (v/v) mixture of (CH3CO)2O, CH3COOH, and H2SO4 at 40 degrees C for 13 h was significantly different from that obtained by the mild acetolysis method; i.e., the amount of mannose was apparently larger than that formed by the mild acetolysis method. In summary, a chemical structure for Fr. J as a highly branched mannan containing 14 different branching moieties was proposed.

Structural analysis of phospho-D-mannan-protein complexes isolated from yeast and mold form cells of Candida albicans NIH A-207 serotype A strain

The immunochemical properties between phospho-D-mannan-protein complexes of yeast (Y) and mycelial (M) forms of Candida albicans NIH A-207 (serotype A) strain were compared. Hydrolysis of the Y-form complex gave a mixture of beta-(1----2)-linked D-mannooligosaccharides consisting mainly of tri- and tetra-ose, whereas the M-form complex gave preponderantly D-mannose. The antiserum against Y-form cells exhibited a lower reactivity with the M-form than with the Y-form complex, whereas the antiserum to M-form cells could not distinguish significantly between both complexes. Moreover, these acid-modified complexes showed lower antibody-precipitating effect than each corresponding intact complex against antisera of Y- and M-form cells. Digestion of the acid-modified Y- and M-form complexes with the Arthrobacter GJM-1 strain alpha-D-mannosidase yielded 35- and 40-% degradation products, respectively. Acetolysis of each modified complex under mild conditions gave the same D-mannohexaose, beta-D-Manp-(1----2)-beta-D-Manp-(1----2)-alpha-D-Manp -(1----2)-alpha-D-Manp- (1----2)-alpha-D-Manp-(1----2)-D-Man. Because the complexes of Y- and M-form cells of C. albicans NIH B-792 (serotype B) strain did not give any hexaose fraction containing beta-(1----2) linkages, the presence of this hexaose can be regarded as one of the dominant characteristics of the serotype-A specificity of C. albicans spp.

The mannoprotein of Saccharomyces cerevisiae is an effective bioemulsifier

The mannoprotein which is a major component of the cell wall of Saccharomyces cerevisiae is an effective bioemulsifier. Mannoprotein emulsifier was extracted in a high yield from whole cells of fresh bakers' yeast by two methods, by autoclaving in neutral citrate buffer and by digestion with Zymolase (Miles Laboratories; Toronto, Ontario, Canada), a beta-1,3-glucanase. Heat-extracted emulsifier was purified by ultrafiltration and contained approximately 44% carbohydrate (mannose) and 17% protein. Treatment of the emulsifier with protease eliminated emulsification. Kerosene-in-water emulsions were stabilized over a broad range of conditions, from pH 2 to 11, with up to 5% sodium chloride or up to 50% ethanol in the aqueous phase. In the presence of a low concentration of various solutes, emulsions were stable to three cycles of freezing and thawing. An emulsifying agent was extracted from each species or strain of yeast tested, including 13 species of genera other than Saccharomyces. Spent yeast from the manufacture of beer and wine was demonstrated to be a possible source for the large-scale production of this bioemulsifier.

Structural study of phosphomannan-protein complex of Citeromyces matritensis containing beta-1,2 linkage. Application of partial acid degradation and acetolysis techniques under mild conditions

The phosphomannan-protein complex of Citeromyces matritensis IFO 0651 strain was investigated for its chemical structure by a sequential degradation procedure, partial acid degradation followed by acetolysis under mild conditions. Upon treatment with 10 mM HCl at 100 degrees C for 1 h, this complex released mannotriose and mannotetraose consisting solely of 1,2-linked beta-D-mannopyranosyl residues, ca. 20% on weight basis of the parent complex. The acid-degraded complex was then subjected to acetolysis using an acetolysis medium of low sulfuric acid concentration, a 100:100:1 (v/v) mixture of acetic anhydride, acetic acid, and sulfuric acid at 40 degrees C for 36 h. A phosphate-containing manno-oligosaccharide fraction eluted in the void-volume region of a Bio-Gel P-2 column was found to consist of Manp beta 1----2Manp beta 1----2Manp alpha 1----2Man to which 1 mol of phosphate group was attached, while a manno-oligosaccharide fraction eluted in the diffusable region was a mixture of Manp beta 1----2Manp beta 1----2Manp beta 1----2Manp alpha 1----2Man, Manp beta 1----2Manp beta 1----2Manp alpha 1----2Man, Manp beta 1----2Manp alpha 1----2Man, Manp alpha 1----2Man, and mannose in the molar ratio of 0.08:0.33:0.19:0.32:1.00. Therefore, the structural analysis of the polysaccharide moiety of a beta-1,2 linkage-containing phosphomannan-protein complex of fungal origin can be achieved by means of a sequential degradation procedure, partial acid degradation followed by acetolysis under mild conditions.

Characterization of phosphomannan-protein complexes isolated from viable cells of yeast and mycelial forms of Candida albicans NIH B-792 strain by the action of Zymolyase-100T

The isolation of phosphomannan-protein complexes from the viable cells of yeast (Y) and mycelial (M) forms of Candida albicans NIH B-792 strain was conducted by treatment with Zymolyase-100T followed by fractional precipitation with cetyltrimethylammonium bromide. The M-form complex was found to contain smaller amount of phosphate (1.3%) than that of the Y-form complex (1.6%). Proton magnetic resonance (PMR) spectra of these complexes indicated that the content of beta-1,2-linked oligomannosyl and nonreducing terminal alpha-1,3-linked mannopyranosyl residues in the M-form complex was lower than that of the Y-form complex. With hot 10 mM HCl, the Y-form complex released a mixture of oligosaccharides ranging from mannose to mannoheptaose, while the M-form complex produced lower oligosaccharides, from mannose to mannotetraose. Upon acetolysis, the acid-modified complex of the M form gave mainly mannotetraose, while that of the Y form produced mainly mannopentaose and mannohexaose in addition to mannotetraose. The average length of branching moieties of the mannan of Y-form cells was therefore longer than that of M-form cells. These results indicate that the Y to M transformation of this C. albicans strain accompanies the suppression of enzyme activity concerning the biosynthesis of mannan such as beta-1,2- and alpha-1,3-mannosyltransferases to synthesize the phosphomannan-protein complex containing mannan moiety with incomplete structure.

Separation of immunomodulatory effects of mannan from Candida albicans into stimulatory and suppressive components

Mannan extracted from Candida albicans was studied for its immunomodulatory activity on in vivo antibody responses to type III pneumococcal polysaccharide (SSS-III), a helper-T-cell-independent antigen, and to sheep erythrocytes (SRBC), a helper-T-cell-dependent antigen. In some studies, the antibody response to SSS-III was converted to a helper-T-cell-dependent response by attaching it to a carrier (horse erythrocytes, HRBC); this complex then was used to immunize mice primed with a subimmunogenic dose of HRBC. Mannan enhanced the antibody response to both SSS-III and SRBC when administered at the same time or 1 or 2 days after immunogen. However, when both mannan and SSS-III were coated onto HRBC for immunization, either enhancement or suppression was noted; the effect depended upon the amount of mannan used. Larger amounts stimulated, whereas smaller amounts suppressed, the antibody response to SSS-III. The enhancing and suppressive components of mannan could be separated by molecular size or charge by chromatography on Sepharose 4B or on DEAE-Sephadex A-50 columns, indicating that mannan extracts contain individual components having opposing immunomodulatory properties. These components can be separated on the basis of molecular size and charge.

Acetolysis of Pichia pastoris IFO 0948 strain mannan containing alpha-1,2 and beta-1,2 linkages using acetolysis medium of low sulfuric acid concentration

To obtain manno-oligosaccharides containing beta-1,2-linked nonreducing terminal groups from the mannan of Pichia pastoris IFO 0948 strain by acetolysis, an attempt was made to establish the reaction conditions under which cleavage of the alpha-1,6 linkage took place preferentially leaving manno-oligosaccharides composed largely of beta-1,2 linkages. By the action of an ordinary acetolysis medium, a 10/10/1 (v/v) mixture of acetic anhydride, acetic acid, and sulfuric acid at 40 degrees C for 13 h or at 25 degrees C for 120 h, the O-acetyl derivative of this mannan gave mannose, mannobiose, mannotriose, and mannopentaose. However, treatment of the same O-acetyl mannan with a 50/50/1 (v/v) acetolysis medium at 40 degrees C for 15 h gave a mannotetraose in addition to mannose, mannobiose, mannotriose, and mannopentaose. Use of a 100/100/1 (v/v) acetolysis medium at 40 degrees C for 36 h gave a more satisfactory result, a mixture of oligosaccharides, from mannose to mannopentaose, which contained more mannotetraose than mannopentaose. Because both mannotetraose and mannopentaose contained alpha-1,2 and beta-1,2 linkages, it was concluded that an acetolysis medium containing a low concentration of sulfuric acid, up to 0.5% (v/v), facilitates the preferential cleavage of the alpha-1,6 linkage, leaving manno-oligosaccharides containing the beta-1,2 linkage which was found to be labile to the action of the 10/10/1 (v/v) acetolysis medium.

Immunochemical study on the mannans of Candida albicans NIH A-207, NIH B-792, and J-1012 strains prepared by fractional precipitation with cetyltrimethylammonium bromide

The mannans of Candida albicans NIH A-207 (A strain, serotype A), C. albicans NIH B-792 (B strain, serotype B), and C. albicans J-1012 (J strain, serotype C) prepared by fractional precipitation with cetyltrimethylammonium bromide (Cetavlon) were investigated for their immunochemical properties. Upon treatment with 10 mM HCl at 100 degrees C for 60 min, the mannans of A and B strains each released a mixture of manno-oligosaccharides ranging from hexaose to mannose together with (for each one) an acid-modified mannan, while J-strain mannan released lower oligosaccharides, tetraose to mannose. The acid-modified mannan of B strain did not show antibody-precipitating activity against homologous antiserum, whereas acid-modified A- and J-strain mannans retained most of this activity. The acid-released oligosaccharides were assumed to consist of beta-1,2-linked D-mannopyranosyl residues from the results of specific rotation and proton magnetic resonance studies.

Immunochemical properties of mannan-protein complex isolated from viable cells of Saccharomyces cerevisiae 4484-24D-1 mutant strain by the action of zymolyase

Viable cells of Saccharomyces cerevisiae 4484-24D-1 mutant strain were treated with an Arthrobacter sp. beta-1,3-glucanase, Zymolyase-60,000, in the presence of a serine protease inhibitor, phenylmethylsulfonyl fluoride. Fractionation of the solubilized materials with Cetavlon (cetyltrimethylammonium bromide) yielded a purified mannan-protein complex, which had a molecular weight of ca. 150,000, approximately three times higher than that of the mannan isolated from the same cells by the hot-water extraction method at 135 C. The amino acid composition of the mannan-protein complex was found to be very similar to that of the mannan-protein complexes of S. cerevisiae X2180-1A wild and S. cerevisiae X2180-1A-5 mutant strains, indicating the presence of large amounts of serine and threonine. It was unexpected that the antibody-precipitating activity of this complex against the homologous anti-whole cell serum was about twice as great as that of the mannan isolated by hot-water extraction. Treatment of this complex with 100 mM NaOH, hot water at 135 C, and pronase, respectively, gave degradation products having the same molecular weight and antibody-precipitating activity as those of the hot-water extracted mannan, allowing the assumption that the protein moiety participated in a large part of this activity.

Isolation of mannan-protein complexes from viable cells of Saccharomyces cerevisiae X2180-1A wild type and Saccharomyces cerevisiae X2180-1 A-5 mutant strains by the action of Zymolyase-60,000

The viable whole cells of Saccharomyces cerevisiae X2180-1A wild type and its mannan mutant strain S. cerevisiae X2180-1A-5, were treated with an Arthrobacter sp. beta-1,3-glucanase in the presence of a serine protease inhibitor, phenyl-methylsulfonyl fluoride. Fractionation of the solubilized materials of each strain with Cetavlon (cetyltrimethylammonium bromide) yielded one mannan-protein complex. Molecular weights of these complexes were almost the same as that of the mannoprotein of the mutant strain prepared by Nakajima and Ballou, which had a molecular weight of 133,000 and were approximately three times larger than those of the mannans isolated from the same cells by hot-water extraction. Each mannan-protein complex contained up to 2% glucose residue, which was not removed by specific precipitation with anti-mannan sera or by affinity chromatography on a column of concanavalin A-Sepharose. Treatment of these complexes with alkaline NaBH4 produced peptide-free mannan containing small amounts of glucose nearly identical to those of the parent complexes. The above findings provide evidence that the glucose residues exist in a covalently linked form to the mannan moiety. Fractionation of the mannan-protein complex of the S. cerevisiae wild-type strain by DEAE-Sephadex chromatography yielded five subfractions of different phosphate content, indicating that these highly intact mannan-protein complexes were of heterogeneous material consisting of many molecular species of different phosphate content.

Immunochemical studies of the mannans of Saccharomyces cerevisiae X2180-1A-5 and Saccharomyces cerevisiae 4484-24D-1 mutant strains, with special reference to their phosphate content

The mannans from Saccharomyces cerevisiae mutant strains X2180-1A-5 and 4484-24D-1, both of which were shown to contain small amounts of phosphate (less than 0.2%), were fractionated on a column of diethylaminoethyl-Sephadex into five subfractions designated as fractions I to V. These subfractions contain different amounts of phosphate, ranging from 0.03 to 0.09 (strain X2180-1A-5) and from 0.01 to 0.17% (strain 4484-24D-1). Fractions I to IV from strain X2180-1A-5 showed nearly identical precipitin activities against the homologous anti-whole cell serum, whereas fraction V, containing the largest amount of phosphate and protein among this mannan subfraction series, showed unexpectedly weaker precipitin activity than those of the other fractions. A synthetic mannan consisting or consecutive alpha-1 leads to 6-linked D-mannopyranosyl residues was found to be cross-reactive with all the mannan subfractions of strain X2180-1A-5 against anti-X2180-1A-5 serum. On the other hand, antibody-precipitating activities of the mannan subfractions of the latter strain were proportional to their phosphate content, although the increments of precipitated antibody nitrogen among the subfractions were quite small. However, fraction V of this mannan subfraction series, containing the largest amounts of phosphate and protein, showed lower precipitin activity than did the other four fractions. These findings indicate that mannans containing no phosphate or relatively small amounts of phosphate, such as those investigated in the present study, are less heterogeneous in the densities of the branching moieties than are highly phosphorylated mannans. These findings suggest that the transfer step of mannosyl-1-phosphate into the precursor(s) of the wild-type strain mannans during the biosynthetic process corresponds to the key reaction responsible for the anionic heterogeneity due to the density heterogeneity of the antigenic determinants.

Growth-inhibitory activity of the D-mannan of Saccharomyces cerevisiae X2180-1A-5 mutant strain against mouse-implanted sarcoma 180 and Ehrlich-carcinoma solid tumor

The D-mannan of Saccharomyces cerevisiae X2180-1A-5 mutant strain, which possesses a main chain composed of alpha-(1 yields 6) linked D-mannopyranosyl residues and a small proportion of branches composed of alpha-(1 yields 2)- and alpha-(1 yields 3)-linked D-mannopyranosyl residues, showed strong growth-inhibitory activity against mouse-implanted Sarcoma 180 and Ehrlich-carcinoma solid tumor. The observation that the level of this activity was nearly identical with that of the D-mannan of a wild-type strain of bakers' yeast, which possesses a high proportion of branches composed of alpha-(1 yields 2)-and alpha-(1 yields 3)-linked D-mannopyranosyl residues, suggests that the branches are not essential for antitumor activity. The partial acid-degradation products of both D-mannans, the molecular weight of which was one-third of that of each parent D-mannan, had only one half of the antitumor activity of the parent D-mannans. This suggests that molecular size is the most important factor for the differences in acitvity of the polysaccharides of wild and mutant strains.

Relationship between phosphate content and serological activities of the mannans of Candida albicans strains NIH A-207, NIH B-792, and J-1012

The mannans from Candida albicans strains NIH A-207 (serotype A), NIH B-792 (serotype B), and J-1012 (serotype C) were fractionated on a column of diethylaminoethyl-Sephadex into five subfractions containing different amounts of phosphate. Antibody-precipitating activities of the mannan subfractions of strains NIH A-207 and NIH B-792 were proportional to their phosphate content, while those of strain J-1012 did not show regularly proportional precipitin activity. A similar tendency was also observed in the cross-reaction between the mannan su,fractions of strains NIH A-207 and J-1012 and their heterologous antisera. The mannans of strain NIH B-792 showed lower cross-reactivities against antisera of strains NIH A-207 and NIH B-792, i.e., only two subfractions containing larger amounts of phosphate were able to react with these antisera.