An acetylated galactoglucomannan from Picea abies L. Karst

A water-soluble galactoglucomannan composed of D-galactose, D-glucose, and D-mannose in 1:3:17 mole proportion has been isolated from the secondary cell walls of Picea abies L. Karst. About 33% of the polysaccharide units were substituted by acetyl groups. Structural studies of the polymer indicated a beta-(1-->4)-linked glucomannopyranosyl backbone with a low content of branch points at O-6 of mannosyl and glucosyl residues. A preference for mannosyl groups indicates the presence of a single D-galactosyl unit side-chain. About half of the mannose residues were O-acetylated at C-2 and C-3 in 1.7:1 mole proportion.     

Synthesis of lupane-type saponins bearing mannosyl and 3,6-branched trimannosyl residues and their evaluation as anticancer agents

The saponins modified with mono- or trimannosyl residues can provide a convenient means of delivering drugs to certain human cells via interactions with mannose receptors. In the study reported therein, we developed a convenient approach for the synthesis of 3-O-mannoside and branched trimannoside derivatives of the saponin lupeol and of C-28 acyl esters of 3-O-acetyl-betulinic acid bearing the same mannosyl entities. Lupeol and 3-O-acetyl-betulinic acid were mannosylated with tetra-O-benzoyl- or tetra-O-acetyl-alpha-D-mannopyranosyl trichloroacetimidates. De-esterification followed by regioselective dimannosylation of the unprotected monosaccharide derivatives with 2equiv of tetra-O-benzoyl-alpha-D-mannopyranosyl trichloroacetimidate selectively yielded O-3,O-6-linked trimannosides. The cytotoxic activity of selected lupane-type saponins (derivatives of lupeol, betulinic acid, and betulin) toward normal human fibroblasts and various cancer cell lines was also compared.     

A galactoxylomannan antigen of Cryptococcus neoformans serotype A

The capsular polysaccharide of Cryptococcus neoformans serotype A was fractionated into two chemically and serologically distinct heteroglycans by differential precipitation with cetyltrimethylammonium bromide (CTAB). The major, viscous, acidic glucuronoxylomannan (GXM, 88% w/w) was precipitated with CTAB, while a previously undetected galactoxylomannan (GalXM, 12% w/w) remained in solution. GalXM is characterized by (i) molar ratios of galactose:mannose: xylose:glucuronic acid of 1.9:1.8:1.0.2 and 2% of O-acetyl; (ii) a molecular weight of 275,000 ± 25,000, estimated by gel-permeation chromatography; (iii) extensive degradation by NaIO₄; (iv) precipitation in gel by a lectin, concanavalin A, indicating nonreducing mannosyl termini; and (v) a distinct, immunoprecipitin arc in counterimmunoelectrophoresis. GalXM was further purified by gel-permeation or ion-exchange chromatography.     

Cryptococcal xylosyltransferase 1 (Cxt1p) from Cryptococcus neoformans plays a direct role in the synthesis of capsule polysaccharides

The opportunistic yeast Cryptococcus neoformans causes serious disease in humans and expresses a prominent polysaccharide capsule that is required for its virulence. Little is known about how this capsule is synthesized. We previously identified a beta1,2-xylosyltransferase (Cxt1p) with in vitro enzymatic activity appropriate for involvement in capsule synthesis. Here, we investigate C. neoformans strains in which the corresponding gene has been deleted (cxt1Delta). Loss of CXT1 does not affect in vitro growth of the mutant cells or the general morphology of their capsules. However, NMR structural analysis of the two main capsule polysaccharides, glucuronoxylomannan (GXM) and galactoxylomannan (GalXM), showed that both were missing beta1,2-xylose residues. There was an approximately 30% reduction in the abundance of this residue in GXM in mutant compared with wild-type strains, and mutant GalXM was almost completely devoid of beta1,2-linked xylose. The GalXM from the mutant strain was also missing a beta1,3-linked xylose residue. Furthermore, deletion of CXT1 led to attenuation of cryptococcal growth in a mouse model of infection, suggesting that the affected xylose residues are important for normal host-pathogen interactions. Cxt1p is the first glycosyltransferase with a defined role in C. neoformans capsule biosynthesis, and cxt1Delta is the only strain identified to date with structural alterations of the capsule polysaccharide GalXM.     

Galactoglucomannan from the secondary cell wall of Picea abies L. Karst

The fine structural features of alkali-extracted galactoglucomannan composed of D-galactose, D-glucose and D-mannose in a 1:8:33 mole proportion from the secondary cell walls of Picea abies L. Karst have been determined. Compositional and methylation analyses of the polymer, partial acid hydrolysis, as well as 1H and 13C NMR measurements of the polymer and products of partial acid hydrolysis confirmed a beta-(1-->4)-linked backbone of galactoglucomannan containing the segments of mannosyl residues (Man2, Man3, Man4, etc.) interrupted with the segments having both mannose and glucose residues, as well as the segments in which D-Glcp units can be adjacent to each other (Glc2). Further, the low content of branching points (approximately 3%) at the positions of 0-6, 0-3 and 0-2 of mannosyl and 0-6 and 0-3 of glucosyl residues, but preferably of mannosyl ones, indicates the presence of short side-chains terminated at position 0-6 predominantly by D-galactose units as single stubs.     

Water-soluble polysaccharides from Ginkgo biloba leaves.

The water-soluble polysaccharides from dried Ginkgo biloba leaves were isolated after exhaustive extraction with organic solvents. The polysaccharide mixture could be separated into a neutral (GF1) and two acidic (GF2 and GF3) polysaccharide fractions by ion exchange chromatography. According to the Mr distribution GF1 and GF3 seemed to be homogenous, whereas GF2 could be further fractionated into two subfractions (GF2a and GF2b) by gel permeation chromatography. GF1 (Mr 23,000) showed the structural features of a branched arabinan. The main chain was composed of 1,5-linked arabinose residues and three in 12 arabinose molecules were branched via C-2 or C-3. GF2a (Mr 500,000) consisted mainly of 1,2,4-branched mannose (29%), 1,4-linked glucuronic (32%) and galacturonic (8%) acid as well as terminal rhamnose (25%). After removal of ca 70% of the terminal rhamnose the remaining polysaccharide showed a decrease in 1,2,4-branched mannose and an increase in 1,2-linked mannose indicating that at least half of the rhamnose residues were linked to mannose via C-4. GF3 (Mr 40,000) consisted of 1,4-linked galacturonic (30%) and glucuronic (16) acid, 1,3,6-branched galactose (15%), 1,2-linked (5%) and 1,2,4-branched (3.5%) rhamnose as well as 1,5-linked arabinose (11%). Rhamnose (5%) and arabinose (10%) were present as terminal groups. Mild acid hydrolysis selectively cleaved arabinose and the remaining polysaccharide showed an increased amount of 1,6-linked and terminal galactose and a decreased quantity of 1,3,6-branched galactose. These results indicated that the terminal as well as the 1,5-linked arabinose were mainly connected to galactose via C-3. The GF3 polysaccharide appeared to be a rhamnogalacturonan with arabinogalactan side chains.     

Some phytotoxic glycopeptides from Ceratocystis ulmi, the Dutch Elm Disease pathogen

Ceratocystis ulmi, the causal agent of Dutch Elm Disease, produces phytotoxic glycopeptides in culture. A mixture of phytotoxic glycopeptides has been prepared by affinity chromatography on a concanavalin A-Sepharose column and collectively they have been termed the toxin. The polydisperse component that makes up the majority of the toxin (80%) by weight has a molecular weight of about 2.7·10⁵. The large molecular weight component (<5%) elutes at the void volume of a Bio-Gel A50 m column. The other component (15%) appears as a trailing peak on the edge of the major component and has an approximate molecular weight of 7 · 10⁴. The toxin is composed of 38% sugar residues, primarily rhamnose and mannose, and 7% amino acid residues. Methylation analysis coupled with mild acid hydrolysis indicates that the backbone of the polysaccharide portion of the toxin is composed of α-1,6-linked mannosyl residues with a 3-linked terminal rhamnosyl residue linked to C-3 of almost every mannosyl residue. The carbohydrate portion of the molecule is linked to the peptide via O-glycosidic linkages to both threonyl and seryl residues. All three components of the toxin are capable of causing wilt in stem cuttings of American elm.     

A water soluble glucomannan isolated from an immunomodulatory active polysaccharide of Salvia officinalis L.

A water soluble glucomannan has been isolated from the decoloured and defatted aerial parts of sage (Salvia officinalis L.) by water extraction, followed by ion-exchange chromatography, and precipitation with Fehling reagent. It was composed of d-glucose and d-mannose residues in the mole ratio of 1.0:1.3 and had M_w ～ 8000. Chemical and spectroscopic analyses revealed a linear structure of the polymer with a backbone composed of β-1,4-linked glucopyranosyl and mannopyranosyl units slightly branched at C-6 by side chains, mainly as single α-glucosyl and mannosyl stubs.     

Host-Pathogen Interactions: XI. Composition and Structure of Wall-released Elicitor Fractions

The structures of the four wall-released elicitor fractions isolated from the Phytophthora megasperma var. sojae mycelial walls have been examined. The results demonstrate that fraction I is primarily composed of a branched β-1,3-glucan, similar in structure to the extracellular elicitors described previously (Ayers, A., J. Ebel, F. Finelli, N. Burger, and P. Albersheim. 1976. Plant Physiol. 57: 751-759). Fractions II and IV are primarily composed of a highly branched mannan-containing glycoprotein, with fraction IV richer in protein than fraction II. Fraction III contains, attached to protein, a mixture of the two polysaccharide types found in fraction I and in fractions II and IV. The structural data presented here, in concert with the biological data presented in the previous two papers (Ayers et al. 1976. Plant Physiol. 57: 751-759; 760-765), demonstrate that the only compound produced by P. megasperma var. sojae which contains elicitor activity is the glucan. Evidence is presented that the terminal glycosyl residues of the glucan are required for elicitor activity. In addition, it is demonstrated that 90% of the glucan can be removed enzymically without any loss of biological activity. The active residue of the enzymic digestion is a highly branched 3- and 3,6-linked glucan containing about 4% mannosyl residues. The results presented suggest that the mannosyl residues of the glucan, which represent only about 1% of the undegraded glucan, are likely to participate in the active site of this molecule. The role of elicitors and phytoalexins in host-pathogen interactions is discussed. Evidence for the existence of and possible identity of another factor, which determines race specificity of host-pathogen interactions, is summarized.     

Structural studies by stepwise enzymatic degradation of the main backbone of soybean soluble polysaccharides consisting of galacturonan and rhamnogalacturonan

Soybean soluble polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides and have a pectin-like structure. The results of a structural analysis of SSPS by using polygalacturonase (PGase) and rhamnogalacturonase (RGase) clarified that the main backbone consisted of galacturonan (GN) and rhamnogalacturonan (RG), which were composed of the diglycosyl repeating unit, -4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-. The side chains of beta-1,4-galactans, branched with fucose and arabinose residues, were linked to the C-4 side of rhamnose residues in the RG regions. The degree of polymerization (dps) of GN, which linked the RG regions together, was estimated to be about 4-10 residues, and some were modified with xylose residues on the C-3 side of the galacturonates. The dps of GN at the reducing end of SSPS was estimated to be about 7-9 residues. Moreover, the fragment of the basic structure of the RG region, -[4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-]2-, some of which had long-chain beta-1,4-galactans branched on the C-4 side of rhamnose residues, were liberated from SSPS by the RGase treatment. The dps of the galactan side chain was estimated to be about 43-47 residues by an analysis of the digestion products from the beta-galactosidase treatment.     

Structure-immunomodulating activity relationships of a pectic arabinogalactan from Vernonia kotschyana Sch. Bip. ex Walp

Structure and immunological characteristics of the pectic arabinogalactan Vk2a (previously reported as Vk100A2a) from the roots of Vernonia kotschyana Sch. Bip. ex Walp. were investigated after enzymatic digestion of the galacturonan moiety and the side chains of the rhamnogalacturonan structure of Vk2a. endo-alpha-D-(1-->4)-Polygalacturonase digestion released the high molecular weight 'hairy region' (Vk2a-HR) and oligogalacturonides. Vk2a-HR consisted of GalA (4-linked) and Rha (2- or 2,4-linked) in a 1:1 ratio, with 60% of Rha branched at C-4. The Rha located in the rhamnogalacturonan core was branched randomly by Gal units. Vk2a-HR was rich in neutral sugars such as Araf 5- (12.2%) and 3,5-substituted (12.8%) and terminally- (14.1%) linked and Gal 4- (13.0%), 3- (0.9%), 6- (2.2%) and 3,6- (1.1%) substituted. Arabinans with chain lengths up to 11 units were identified. Araf residues were attached to C-3 of alpha-L-(1-->5)-Araf chains and to C-4 of Gal residues. Single Gal units and chains of beta-D-(1-->6)-linked galacto di- to penta-saccharides were attached to a beta-D-(1-->3)-galactan core. All the enzyme resistant fractions expressed potent complement fixation and induction of B-cell mitogenic activity, and the present study indicates that there may be several and possibly structurally different active sites involved in the bioactivity of Vk2a. The bioactive sites may be located both in the more peripheral parts of the molecule but also in the inner core of the 'hairy region' or in larger enzyme-resistant chains.     

Further studies on the composition and structure of a fucoidan preparation from the brown alga Saccharina latissima

The polysaccharide composition of a fucoidan preparation isolated from the brown alga Saccharina latissima (formerly Laminaria saccharina) was reinvestigated. The preparation was fractionated by anion-exchange chromatography, and the fractions obtained were analyzed by chemical methods combined with NMR spectroscopy. Several 2D procedures, including HSQC, HMQC-TOCSY, and HMQC-NOESY, were used to obtain reliable structural information from the complex spectra, and the signal assignments were additionally confirmed by comparison with the literature spectra of the related polysaccharides and synthetic oligosaccharides. In accordance with the previous data, the main polysaccharide component was shown to be a fucan sulfate containing a backbone of 3-linked α-l-fucopyranose residues sulfated at C-4 and/or at C-2 and branched at C-2 by single sulfated α-l-fucopyranose residues. In addition, three other types of sulfated polysaccharide molecules were detected in the total fucoidan preparation: (i) a fucogalactan having a backbone of 6-linked β-d-galactopyranose residues branched mainly at C-4 and containing both terminal galactose and fucose residues; (ii) a fucoglucuronomannan having a backbone of alternating 4-linked β-d-glucopyranosyluronic acid and 2-linked α-d-mannopyranose residues with α-l-fucopyranose residues as single branches at C-3 of α-d-Manp; and (iii) a fucoglucuronan having a backbone of 3-linked β-d-glucopyranosyluronic acid residues with α-l-fucopyranose residues as single branches at C-4. Hence, even a single algal species may contain, at least in minor amounts, several sulfated polysaccharides differing in molecular structure. Partial resolution of these polysaccharides has been accomplished, but unambiguous evidence on their presence as separate entities was not obtained.     

The 5-O-beta-D-galactofuranosyl-containing peptidophosphogalactomannan of Penicillium charlesii. Characterization of the mannan by 13C NMR spectroscopy

Penicillium charlesii secretes a galactofuranosyl and phosphodiester-containing peptidophosphogalactomannan (pPGM). A linear mannan was prepared from pPGM by treatment with 48% aqueous HF which selectively cleaves galactofuranosyl and phosphodiesters; treatment with alkaline borohydride releases the mannan from the polypeptide. Mannan from P. charlesii cultured in D-[1,2-13C2]glucose contained mannopyranosyl residues which were enriched in 13C at both C-1 and C-2 and, to a lesser extent, at C-5 and C-6. The mannan was examined with a combination of 13C NMR INADEQUATE pulse sequence and selective 13C saturation to assign the resonance frequency of anomeric carbons directly coupled to specific C-2 signals. Three species of mannosyl residues, each substituted with a glycosidic linkage at C-2, and a fourth species substituted at C-6 and not substituted at C-2 were observed. Mannan obtained from P. charlesii cultured in D-[6-13C]glucose contained mannopyranosyl residues which were enriched in 13C primarily in C-6. The mannan was examined by DEPT 13C NMR to determine the number of species which were substituted at C-6. Mannan, treated as described above, contained a 1----6-linked mannopyranosyl species. pPGM contains minor quantities of at least four other substances attached to hydroxymethyl groups of the hexosyl residues.     

Structure of a fucoidan from the brown seaweed Fucus serratus L

A fucoidan consisting of L-fucose, sulfate and acetate in a molar proportion of 1:1:0.1 and small amounts of xylose and galactose were isolated from the brown seaweed Fucus serratus L. The fucoidan structure was investigated by 1D and 2D 1H and 13C NMR spectroscopy of its desulfated and de-O-acetylated derivatives as well as by methylation analysis of the native and desulfated polysaccharides. A branched structure was suggested for the fucoidan with a backbone of alternating 3- and 4-linked alpha-L-fucopyranose residues, -->3)-alpha-L-Fucp-(1-->4)-alpha-L-Fucp-(1-->, about half of the 3-linked residues being substituted at C-4 by trifucoside units alpha-L-Fucp-(1-->4)-alpha-L-Fucp-(1-->3)-alpha-L-Fucp-(1-->. Minor chains built up of 4-linked alpha-fucopyranose and beta-xylose residues were also detected, but their location, as well as the position of galactose residues, remained unknown. Sulfate groups were shown to occupy mainly C-2 and sometimes C-4, although 3,4-diglycosylated and some terminal fucose residues may be nonsulfated. Acetate was found to occupy C-4 of 3-linked Fuc and C-3 of 4-linked Fuc in a ratio of about 7:3.     

EXTRACELLULAR MATRIX ASSEMBLY IN DIATOMS (BACILLARIOPHYCEAE). V. ENVIRONMENTAL EFFECTS ON POLYSACCHARIDE SYNTHESIS IN THE MODEL DIATOM,PHAEODACTYLUM TRICORNUTUM1

The effects of phosphate (P) limitation, varying salinity (5–65 psu), and solid media growth conditions on the polysaccharides produced by the model diatom, Phaeodactylum tricornutum Bohlin were determined. Sequential extraction was used to separate polymers into colloidal (CL), colloidal extracellular polymeric substances (cEPS), hot water soluble (HW), hot bicarbonate soluble (HB), and hot alkali (HA) soluble fractions. Media‐soluble polymers (CL and cEPS) were enriched in 4‐linked mannosyl, glucosyl, and galactosyl residues as well as terminal and 3‐linked xylosyl residues, whereas HW polymers consisted mainly of 3‐linked glucosyl as well as terminal and 2,4‐linked glucuronosyl residues. The HB fraction was enriched in terminal and 2‐linked rhamnosyl residues derived from the mucilage coating solubilized by this treatment. Hot alkali treatment resulted in the complete dissolution of the frustule releasing 2,3‐ and 3‐linked mannosyl residues. The fusiform morphotype predominated in standard and P‐limited cultures and cultures subjected to salinity variations, but growth on solid media resulted in an enrichment of the oval morphotype. The proportion and linkages of 15 residues, including neutral, uronic acid, and O‐methylated sugars, varied with environmental conditions. P limitation and salinity changes resulted in 1.5‐ to 2.5–fold increase in carbohydrate production, with enrichment of highly branched/substituted and terminal rhamnose, xylose, and fucose as well as O‐methylated sugars, uronic acids, and sulfate. The increased deoxy‐ and O‐methylated sugar content under unfavorable environments enhances the hydrophobicity of the polymers, whereas the anionic components may play important roles in ionic cross‐linking, suggesting that these changes could ameliorate the effects of salinity or P‐stress and that these altered polysaccharide characteristics may be useful as bioindicators for environmental stress.     

A Single Arabinan Chain Is Attached to the Phosphatidylinositol Mannosyl Core of the Major Immunomodulatory Mycobacterial Cell Envelope Glycoconjugate,Lipoarabinomannan

Lipoarabinomannan (LAM) is composed of a phosphatidylinositol anchor followed by a mannan followed by an arabinan that may be capped with various motifs including oligosaccharides of mannose. A related polymer, lipomannan (LM), is composed of only the phosphatidylinositol and mannan core. Both the structure and the biosynthesis of LAM have been studied extensively. However, fundamental questions about the branching structure of LM and the number of arabinan chains on the mannan backbone in LAM remain. LM and LAM molecules produced by three different glycosyltransferase mutants of Mycobacterium smegmatis were used here to investigate these questions. Using an MSMEG_4241 mutant that lacks the α-(1,6)-mannosyltransferase used late in LM elongation, we showed that the reducing end region of the mannan that is attached to inositol has 5–7 unbranched α-6-linked-mannosyl residues followed by two or three α-6-linked mannosyl residues branched with single α-mannopyranose residues at O-2. After these branched mannosyl residues, the α-6-linked mannan chain is terminated with an α-mannopyranose at O-2 rather than O-6 of the penultimate residue. Analysis of the number of arabinans attached to the mannan core of LM in two other mutants (ΔembC and ΔMSMEG_4247) demonstrated exactly one arabinosyl substitution of the mannan core suggestive of the arabinosylation of a linear LM precursor with ∼10–12 mannosyl residues followed by additional mannosylation of the core and arabinosylation of a single arabinosyl “primer.” Thus, these studies suggest that only a single arabinan chain attached near the middle of the mannan core is present in mature LAM and allow for an updated working model of the biosynthetic pathway of LAM and LM.     

Branched glucan from the fruiting bodies of Piptoporus betulinus (Bull.:Fr.) Karst

A new glucan, namely, piptoporane I, with a molecular mass of 270 kDa was isolated from fruiting bodies of Piptoporus betulinis (Bull.:Fr.) Karst. (Fomitopsidacaeae). Using a combination ofphysicochemical methods, it was established that piptoporane I was a branched glucan with a backbone consisting of alpha-( 1->3)-glucopyranose residues substituted at the C-6 position by single residues of beta-D-glucopyranose by 17.3%. A polysaccharide with such a structure was isolated for the first time from the fungus genus Piptoporus.     

Reactivity of Limulus amoebocyte lysate towards (1----3)-beta-D-glucans

The structure activity relationship for beta-D-glucans for the gelation of the amoebocyte lysates of the horseshoe crab (Limulus) has been investigated. beta-D-Glucans that had no (1----3) linkages induced little or no gelation. The (1----3)-beta-D-glucans curdlan (unbranched), grifolan (approximately 33% branched), schizophyllan (approximately 33% branched), lentinan (approximately 40% branched). SSG (approximately 50% branched), and OL-2 (approximately 66% branched) induced significant gelation. The optimum concentration for gelation was correlated with the content of branching. Single chain (rather than a triple helix) conformation and higher molecular weight were associated with higher reactivity.     

An extracellular polysaccharide produced by Zoogloea ramigera 115

A weakly acidic polysaccharide was purified from the extracellular zoogloeal matrix produced by Zoogloeal ramigera 115. The purified polysaccharide was homogeneous as judged by sedimentation analysis, and the average molecular weight was estimated to be about 10(5) by gel permeation chromatography of the fully methylated preparation. The polysaccharide was composed of D-glucose, D-galactose and pyruvic acid in an approximate molar ratio 11:3:1.5. On the basis of methylation, periodate oxidation, Smith degradation and partial hydrolysis, the following highly branched structure was deduced for the polysaccharide: a long chain mainly consisting of beta 1 leads to 4-linked glucose residues branching at the C-3 or C-6 position of galactose residues which are present in beta 1 leads to 4 or beta 1 leads to 3 linkages as the minor component of the long chain; pyruvic acid residues, the sole acidic component, are linked to the nonreducing end and/or 1,3-linked glucose residues through 4,6-ketal linkages. The purified polysaccharide was not readily soluble in water and had a high affinity for several metallic ions (e.g, 0.25 mumol Fe3+/mg, and 0.17 mumol Fe2+ mg). Upon addition of metallic ions (1 mM) to a gelatinous aqueous solution of the polysaccharide (K+ form, 0.125%), more than 80% of it immediately coprecipitated out with them.     

Mechanism of glucan-induced agglutination in Streptococcus mutans. I. Binding of radioactive glucan to whole cells of S. mutans OMZ-176.

The binding of radioactive glucan to Streptococcus mutans cells, which are agglutinated by dextrans, was examined. The glucan was synthesized from sucrose by extracellular glucosyltransferases from S. mutans FA-1 and was highly branched at C-3 and C-6 of D-glucose residues, containing 17% of a (1 leads to 3)inter-chain residues. Binding of glucan to whole cells of S. mutans OMZ-176, which were agglutinated by addition of glucan or Dextran T2000, was irreversible and followed saturation type kinetics; saturation was achieved at approximately 110 ng of glucan per ml. About 14 ng of glucan were bound per mg of the cells at the saturated concentration. The heated cells of this organism, however, had a relatively low ability of glucan-binding, compared with the freshly prepared and lyophilized cells. Binding to the heated cells was entirely of a non-saturation type. Binding of Dextran T2000 or T10 was determined by competition between the labeled glucan and unlabeled Dextrans for the binding site(s). Both Dextrans and glucan from S. mutans FA-1 were bound to the same site(s). Other organisms, which did not undergo glucan- and Dextran-induced agglutination, had a relatively lower ability of glucan-binding than S. mutans, which was agglutinated.