Biosynthetic processing of the oligosaccharide chains of cellular fibronectin

We have examined the maturation or processing of the oligosaccharides of cellular fibronectin in cultured chick embryo fibroblasts. Fibronectin was pulse-labeled with [2-³H]mannose or [³⁵S]methionine, and the turnover rates of carbohydrate and polypeptide portions of immunoprecipitated fibronectin were compared. The oligosaccharides on fibronectin were analyzed by gel electrophoresis for alterations in sensitivity to the enzyme endo-β-N-acetylglucosaminidase H, which specifically cleaves the ‘high-mannose’ class of asparagine-linked oligosaccharide. Incorporated mannose was removed only at early time points, suggesting that the structure of fibronectin oligosaccharides was altered due to processing.This possibility was confirmed by the analysis of glycopeptides generated by exhaustive pronase digestion. Two major glycopeptide structures were detected; their properties correspond to a ‘high-mannose’ oligosaccharide precursor and a ‘complex’ carbohydrate product. The precursor-product relationship of these two forms of oligosaccharide chains was demonstrated by pulse-chase labeling experiments. The precursor glycopeptide had an apparent size (M_r 2100) comparable to (Man)₉GlcNAc (M_r 2080), and was sensitive to endo-β-N-acetylglucosaminidase H; nearly all of the labeled mannose incorporated in a 10 min pulse was released from fibronectin glycopeptides by this enzyme. During a 90 min chase period, the glycopeptides became larger and increasingly resistent to endo-β-N-acetylglucosaminadase H cleavage. The final ‘complex’ or processed oligosaccharide structure contained approximately two-thirds less associated with the mature glycoprotein. They also indicate that the ‘complex’ structure is synthesized as a ‘high-mannose’ intermediate which is processed by the removal of mannose.     

Light-dependent incorporation of selenite and sulphite into selenocysteine and cysteine by isolated pea chloroplasts

Illuminated intact pea chloroplasts in the presence of O-acetylserine (OAS) catalysed incorporation of SeO₃^2- and SO₃^2- into selenocysteine and cysteine at rates of ca 0.36 and 6 μmol/mg Chl per hr respectively. Sonicated chloroplasts catalysed SeO₃^2- and SO₃^2- incorporation at ca 3.9 and 32% respectively of the rates of intact chloroplasts. Addition of GSH and NADPH increased the rates to ca 91 and 98% of the intact rates, but SeO₃^2- incorporation under these conditions was essentially light-independent. In the absence of OAS, intact chloroplasts catalysed reduction of SO₃^2- to S^2- at rates of ca 5.8 μmol/mg Chl per hr. In the presence of OAS, S^2- did not accumulate. Glutathione (GSH) reductase was purified from peas and was inhibited by ZnCl₂. This enzyme, in the presence of purified clover cysteine synthase, OAS, GSH and NADPH, catalysed incorporation of SeO₃^2- into selenocysteine (but not SO₃^2- into cysteine). The reaction was inhibited by ZnCl₂. Incorporation of SeO₃^2- into selenocysteine by illuminated intact chloroplasts and sonicated chloroplasts (with NADPH and GSH) was also inhibited by ZnCl₂ but not by KCN. Conversely, incorporation of SO₃^2- into cysteine was inhibited by KCN but not by ZnCl₂. It was concluded that SeO₃^2- and SO₃^2- are reduced in chloroplasts by independent light-requiring mechanisms. It is proposed that SeO₃^2- is reduced by light-coupled GSH reductase and that the Se^2- produced is incorporated into selenocysteine by cysteine synthase.     

Analytical and structural features of the gum exudate from Combretum hartmannianum schweinf.

The gum exudate from Combretum hartmannianum is water-soluble, forms very viscous solutions, and contains galactose (22%), arabinose (43%), mannose (10%), xylose (6%), rhamnose (4%), glucuronic acid (6%), 4-O-methylglucuronic acid (2%), and galacturonic acid (7%). The acidic components produced on hydrolysis of the gum were 6-O-(β-D-glucopyranosyluronic acid)-D-galactose, and two saccharides that had the same chromatographic mobility, and contained mannose and galacturonic acid, and galactose and 4-O-methylglucuronic acid, respectively. Methylation and methanolysis of the gum indicated the presence of terminal uronic acid, rhamnose, xylose, galactose, arabinofuranose, and arabinopyranose. Controlled, acid hydrolysis indicated the presence of (1→3)-linked arabinopyranose side-chains and (1→6)-linked galactose residues. C. hartmannianum gum, when subjected to two Smith-degradations, yielded Polysaccharides I and II, both of which contained galactose, arabinose, and mannose. Insufficient crude gum was available for a complete structural study, but the molecule was shown to contain long, sparsely branched chains of (1→6)-linked galactose residues, to which are attached (1→3)-linked arabinose and (1→3)-linked mannose side-chains.     

Enhanced stereoselectivity of α-mannosylation under thermodynamic control using trichloroacetimidates

O-Specific polysaccharides of Vibrio cholerae O1, serotypes Inaba and Ogawa, consist of α-(1→2)-linked N-(3-deoxy-l-glycero-tetronyl)perosamine (4-amino-4,6-dideoxy-d-mannose). The blockwise synthesis of larger fragments of such O-PSs involves oligosaccharide glycosyl donors that contain a nonparticipating 2-O-glycosyl group at the position vicinal to the anomeric center where the new glycosidic linkage is formed. Such glycosyl donors may bear at C-4 either a latent acylamino (e.g., azido) or the 3-deoxy-l-glycero-tetronamido group. While monosaccharide glycosyl donors, even those bearing a nonparticipating group at O-2 (e.g., methyl), and the 4-N-(3-deoxy-l-glycero-tetronyl) side chain form α-linked oligosaccharides with excellent stereoselectivity, α-mannosylation with analogous oligosaccharide donors in this series is adversely affected by the presence of the side chain. Consequently, the unwanted β-product is formed in a considerable amount. Conducting the reaction at elevated temperature under thermodynamic control substantially enhances formation of the α-linked oligosaccharide. This effect is much more pronounced when glycosyl trichloroacetimidates, rather than thioglycosides or glycosyl chlorides, are used as glycosyl donors.     

Substrate Specificities of N-Acetylglucosaminyl-, Fucosyl-, and Xylosyltransferases that Modify Glycoproteins in the Golgi Apparatus of Bean Cotyledons

As part of their posttranslational maturation process, newly synthesized glycoproteins that contain N-linked oligosaccharide side chains pass through the Golgi apparatus, where some of their oligosaccharides become modified by carbohydrate processing reactions. In this paper, we report the presence of Golgi-localized enzymes in plant cells (Phaseolus vulgaris cotyledons) that transfer GlcNAc, fucosyl, and xylosyl residues to the oligosaccharide side chains of glycoproteins. All three enzyme activities are involved in the transformation of high mannose side chains into complex glycans. As judged by acceptor specificity studies, at least two GlcNAc residues can be added to the nonreducing side of high mannose oligosaccharides, which have been trimmed by α-mannosidase(s). A Man₅(GlcNAc)₂-peptide serves as the acceptor for the first GlcNAc added. The second GlcNAc can be added only after the prior removal of two additional mannose residues, ultimately yielding (GlcNAc)₂Man₃(GlcNAc)₂-peptide. Fucosyltransferase can transfer fucose to GlcNAcMan₅(GlcNAc)₂Asn, GlcNAcMan₃(GlcNAc)₂Asn, and (GlcNAc)₂Man₃(GlcNAc)₂Asn; xylosyltransferase exhibits significant activity toward the latter two substrates only. These results suggest an overlapping sequence of oligosaccharide modification in the Golgi apparatus that, in regard to GlcNAc and fucose additions, is analogous to pathways of oligosaccharide processing reported for animal cells. To our knowledge, this is the first report characterizing a xylosyltransferase involved in N-linked oligosaccharide modification, an activity that is apparently absent in most animal cells.     

The use of 1-O-tosyl-d-glucopyranose derivatives in α-d-glucoside synthesis

1-O-Tosyl-d-glucopyranose derivatives having a nonparticipating benzyl group at O-2 have been shown to react rapidly in various solvents with low concentrations of alcohols, either methanol or methyl 2,3,4-tri-O-benzyl-α-d-glucopyranoside. The stereospecificity of the glucoside-forming reaction could be varied from 80% of β to 100% of α anomer by changing the solvent or modifying the substituents on the 1-O-tosyl-d-glucopyranose derivative. 2,3,4-Tri-O-benzyl-6-O-(N-phenylcarbamoyl)-1-O-tosyl-α-d-glucopyranose in diethyl ether gave a high yield of α-d-glucoside. Kinetic measurements of reaction with various alcohols (methanol, 2-propanol, and cyclohexanol) show a high rate even at low concentrations of alcohol, and give some insight into the reaction mechanism. The high rate and stereoselectivity of their reaction suggest that the 1-O-tosyl-d-glucopyranose derivatives may be used as reagents for oligosaccharide synthesis.     

Studies on lectins XXXV. Water-soluble O-glycosyl polyacrylamide derivatives for specific precipitation of lectins

By copolymerization of acrylamide and allyl glycosides of various sugars, O-glycosyl derivatives of polyacrylamide copolymers were prepared. The sugar content of the copolymers can be varied in the range 0–40%, their sedimentation coefficient shows the values of 2.5–2.7 S; the molecular weight of an $\text{O-α-}\text{d}\text{-}\text{mannopyranosyl}$ polyacrylamide copolymer (29% mannose, s_20,w⁰ = 2.9 S) was estimated as 44 500. Copolymers with incorporated glycosyl residues interacting specifically with lectins yield precipitates with them upon immunodiffusion in cellulose acetate. The quantitative precipitin curves obtained with these copolymers are similar to those produced by quantitative precipitation of lectins with natural polysaccharides. The copolymers may serve as model substances of natural polysaccharides.     

Structural investigations on two hemicellulosic polysaccharides from groundnut (Arachis hypogea) seed endosperm

A highly branched xylan and a linear, β-d-(1→4)-linked glucomannan are the two hemicellulosic components isolated from the endosperms of groundnut (Arachis hypogea). Electrophoretic, sedimentation, and sugar analysis indicate the polysaccharides to be fairly homogeneous. The O-methyl derivatives of the polysaccharides were analysed, after reduction and O-acetylation, by gas-liquid chromatography and g.l.c.-mass spectrometry. 2,3,4-Tri-O-methyl-d-xylose (3.6 mol), 2,3-di-O-methyl-d-xylose (21.0 mol), 3-O-methyl-d-xylose (2.8 mol), and d-xylose (4.2 mol) were detected in the xylan, whereas 2,3,4,6-tetra-O-methyl-d-glucose and/or mannose (1.6 mol), 2,3,6-tri-O-methyl-d-mannose (5.6 mol), and 2,3,6-tri O-methyl-d-glucose (21.2 mol) were found in the glucomannan. Periodate and Smith-degradation studies substantiate the results of methylation analysis on the xylan. A glucose: mannose ratio of 3:1 for the glucomannan, however, suggests that this fraction may be an aggregate of true glucomannan and glucan or degraded cellulose.     

Biosynthesis and characterization of large dolichyl diphosphate-linked oligosaccharides in Sacchromyces cerevisiae

Yeast membranes incorporate radioactivity from GDP[¹⁴C]mannose into various glycolipids. These can be separated by thin layer chromatography into at least seven components.The major component has been identified previously as dolichyl monophosphate mannose. Only one additional component is not sensitive to mild alkaline saponification, but is hydrolyzed instead under mild acidic conditios. This latter glycolipid has all the characteristics of a polyprenyl diphosphate oligosaccharide with a sugar moiety of more than 12 hexose units. It runs like dolichyl diphosphate derivatives on a DEAE column and evidence is presented that the lipid moiety is a polyprenol.When radioactive Dol-PP-di-N-acetylchitobiose is incubated with yeast membranes in the presence of non-radioactive GDPmannose a small amount of a larger lipid oligosaccharide is formed besides the previously-described Dol-PP-(GlcNAc₂ mannose. This oligosaccharide has all the properties of the glycolipid described above. Its formation is greatly increased when Triton is omitted from the incubation. Radioactivity of the polyprenyl diphosphate [¹⁴C]oligosaccharide is transferred to ethanol-insoluble material, most likely endogenous membrane glycoproteins.     

Synthesis and hybridization of 2′-O-methyl-RNAs incorporating 2′-O-carbamoyluridine and unique participation of the carbamoyl group in U–G base pair

2′-O-Carbamoyluridine (U_cm) was synthesized and incorporated into DNAs and 2′-O-Me-RNAs. The oligonucleotides incorporating U_cm formed less stable duplexes with their complementary and U_cm–U, U_cm–C single-base mismatched DNAs and RNAs in comparison with those without the carbamoyl group. On the contrary, the T_m analyses revealed that the duplexes with a mismatched U_cm–G base pair showed almost the same thermostability as the corresponding unmodified duplexes. Molecular dynamics (MD) simulations of the U_cm-modified 2′-O-Me-RNA/RNA duplexes with U_cm–G mismatched base pair suggested that the carbamoyl group could participate in the U_cm–G base pair by an additional intermolecular hydrogen bond between the carbamoyl oxygen and the H2 of the guanine base.     

The mechanism of synthesis of the polysaccharide part of mannan in Saccharomyces cerevisiae

Saccharomyces cerevisiae wild-type and mutant cells affected in the structure of mannan outer chain were shown to possess in vivo one major dolichol-P-P-bound oligosaccharide. The size, monosaccharide composition, and pattern obtained upon acetolysis and paper chromatography of the oligosaccharide were the same for all strains and for the main corresponding compound isolated from animal tissues. Evidence is presented indicating that the dolichol-P-P derivative occurring in vivo, and containing 2-N-acetylglucosamine, 9-mannose, and 3-glucose residues, is the intermediate involved in yeast protein glycosylation. The transfer of the oligosaccharide to protein was followed in vivo by the excision of the glucose and at the most one mannose residue. Mannoses were then added to the trimmed saccharide moiety. No difference between the first stages (i.e., excision of monosaccharides) of the processing of the protein-bound oligosaccharides by wild-type and mutant cells was found. However, mutants carrying the mnn 1 mutation, which are known to be devoid of terminal α(1–3)-linked mannose residues in the mannan outer chain and inner core, were found not to add such mannose residues to the already glucose-free protein-bound oligosaccharide.     

Oligosaccharides on cathepsin D from porcine spleen

Cathepsin D from porcine spleen contained mannose (3.3%), glucosamine (1.4%), and mannose 6-phosphate (0.08%). Essentially all of the oligosaccharides of cathepsin D could be released by endo-β-N-acetylglucosaminidase H, pointing to oligomajmoside types of structures. Three neutral oligosaccharide fractions, containing 5, 6, and 7 mannose residues, respectively, were isolated by gel permeation chromatography on Bio-Gel P-2. Studies using exoglycosidase digestions and 500-MHz ¹H NMR spectroscopy revealed that their structures are [Manα1 → 2]_{0 or 1}Manα1 → 6[Manα1 → 3]Manα1 → 6[(Manα1 → 2)_{0 or 1}Manα1 → 3]Manβ1 → 4GlcNAcβ1 → 4 GlcNAc. These structures are identical to what have recently been proposed by Takahashi et al. for the major oligosaccharide units of cathepsin D from the same source (T. Takahashi P.G. Schimidt, and J. Tang (1983)J. Biol. Chem.258, 2819–2930), except for the occurrence of two isomeric oligosaccharides containing six mannoses. Only a part (3.4%) of the oligosaccharides were acidic, containing phosphates in monoester linkage. The phosphorylated oligosaccharides also consisted of oligomannoside-type chains which were analogous to, but more heterogeneous in size than the neutral oligosaccharides. Cathepsin D was bound to a mannose- and N-acetylglucosamine-specific lectin (mannan-binding protein) isolated from rabbit liver with the K_i value of 5.4 × 10^?6m.     

Effect of divalent metal ions on the synthesis of oligosaccharide side chains of Neurospora crassa glycoproteins

Neurospora crassa membrane preparations incorporated mannose from GDP-mannose-[¹⁴C] in the presence of Mg²⁺ into a polyprenol lipid and side chains of protein acceptor(s), which are labile on hydrolysis in weak base. The addition of Mn²⁺ to the reaction mixtures does not affect mannosyl lipid synthesis but it stimulates the transfer of mannose to larger oligosaccharide chains resistant to β-elimination and the transfer of a second mannosyl unit to form an O-glycosidically linked mannobiosyl side chain. Incubation of particulate preparations with polyprenol-mannose-[¹⁴C] in the presence of Mg²⁺ and Mn²⁺ also results in the transfer of a single mannose to the protein. When non-radioactive GDP-mannose is added to this reaction mixture, however, β-elimination yields mannobiose. The mannobiose is labeled in the reducing sugar only. These results indicate that the first mannose of this mannobiosyl side chain is transferred via a lipid intermediate, but the second mannose is transferred directly from GDP-mannose. In the presence of Mg²⁺ and Mn²⁺, mannose apparently is also transferred from polyprenol-mannose-[¹⁴C] to side chains which are resistant to hydrolysis.     

Structural studies of sapote (Sapota achras) gum

Sapote gum contains residues of L-arabinose (pyranose and furanose), D-xylose, D-glucuronic acid, and 4-O-methyl-D-glucuronic acid in the ratio 1.0:2.8:0.48:0.52. The two uronic acids were conveniently determined by reducing the carboxyl functions with lithium borohydride and measuring the ratio of D-glucose to 4-O-methyl-D-glucose. Periodate oxidation of the carboxyl-reduced gum gave inter alia 2-O-methyl-D-erythritol and 4-O-methyl-D-glucose in amounts suggesting that 37% of the 4-O-methyl-D-glucuronic acid residues are unsubstituted in the polysaccharide. Acetolysis of the carboxyl-reduced gum gave O-α-D-glucopyranosyl-(1→2)-(4-O-β-D-xylopyranosyl)_0,1,2,-D-xylose, a hitherto undescribed series of oligosaccharides, together with 2-O-(4-O-methyl-α-D-glucopyranosyl)-D-xylose. Methylation confirmed that sapote gum has a highly branched structure, and commercial xylanases did not depolymerize the gum. An α-L-arabinofuranosidase liberated a substantial part of the arabinose residues. Sapote gum is a member of the uncommon class of plant gums having a D-xylose backbone and structurally resembles brea gum.     

Biosynthesis of internally branched monomethylalkanes in the cockroach Periplaneta fuliginosa.

Sodium [1-¹⁴C]acetate, sodium [1-¹⁴C]propionate, sodium [2-¹⁴C]propionate, sodium [3-¹⁴C]propionate and sodium [methyl-¹⁴C]methylmalonate were readily incorporated into the cuticular hydrocarbons of nymphal stages of the cockroach Periplaneta fuliginosa both in vivo and in vitro, whereas no incorporation of [methyl-¹⁴C]methionine was observed. The alkanes of the nymphal stages of this insect are 25+% n-alkanes, 14% 3-methylalkanes, and 59+% internally branched monomethylalkanes, principally 13-methylpentacosane. Sodium [1-¹⁴C]acetate was incorporated into each class of alkane at about its percentage composition. In contrast, labeled sodium propionate and sodium methylmalonate were preferentially incorporated into the branched fractions. Radio-gas-liquid chromatography showed that sodium [1-¹⁴C]propionate was incorporated almost exclusively into 3-methyltricosane and 13-methylpentacosane, whereas sodium [1-¹⁴C]acetate was incorporated into each glc peak at about its percentage composition. These data suggest that propionate, incorporated during chain elongation, serves as the branching methyl group donor for both the 3-methyl and the internally branched monomethylalkanes in insects. The location of hydrocarbon synthesis in P. fuliginosa was studied using an in vitro tissue slice system. Excised cuticle slices, with adhering fat body tissue removed, gave good incorporation of labeled substrates into the hydrocarbon fraction. No hydrocarbon synthesis was observed in fat body preparations.     

Production of a hybrid 16-membered macrolide antibiotic by genetic engineering of Micromonospora sp. TPMA0041

Some polyketide-derived bioactive compounds contain sugars attached to the aglycone core, and these sugars often enhance or impart specific biological activity to the molecule. Mycinamicin II, a 16-member macrolide antibiotic produced by Micromonospora griseorubida A11725, contains a branched lactone and two different deoxyhexose sugars, d-desosamine and d-mycinose, at the C-5 and C-21 positions, respectively. We previously engineered an expression plasmid pSETmycinose containing the d-mycinose biosynthesis genes from M. griseorubida A11725. This plasmid was introduced into Micromonospora sp. FERM BP-1076 cells, which produce the 16-membered macrolide antibiotic izenamicin. The resulting engineered strain TPMA0041 produced 23-O-mycinosyl-20-deoxy-izenamicin B₁ and 22-O-mycinosyl-izenamicin B₂. 23-O-mycinosyl-20-deoxy-izenamicin B₁ has been produced by the engineered strain M. rosaria TPMA0001 containing pSETmycinose as 23-O-mycinosyl-20-deoxo-20-dihydro-12,13-deepoxyrosamicin (=IZI) in our recent study, and 22-O-mycinosyl-izenamicin B₂ has previously been synthesized as a macrolide antibiotic TMC-016 with strong antibacterial activity. The production of 22-O-mycinosyl-izenamicin B₂ (=TMC-016) was increased when propionate, a precursor of methylmalonyl-CoA, was added to the culture broth.     

Studies on the carbohydrate moiety of vitellogenin from the tobacco hornworm,Manduca sexta

Vitellogenin can be isolated in large quantities from the hemolymph of the tobacco hornworm, Manduca sexta by a combination of KBr density gradient ultracentrifugation, gel permeation and cation exchange chromatography. Glycopeptides generated by exhaustive pronase digestion of vitellogenin were separated by gel permeation chromatography on a Bio-Gel P-6 column. The major glycopeptide was shown to bind to concanavalin A-Sepharose but not to lentil lectin-Sepharose and was sensitive to treatment with endo-β-N-acetylglucosaminidase H. Analysis of the glycopeptide by high field proton NMR spectroscopy revealed that the primary structure is of the high mannose class containing nine mannose and two N-acetylglucosamine units. These results suggested that N-glycosylation of insect proteins, as in mammals, yeasts and plants, involves the en bloc transfer of an oligosaccharide containing the unit (Glu)₃(Man)₉(GlcNAc)₂ from a lipid intermediate to an asparagine residue followed by removal of glucose residues. Processing to more complex structures does not seem to occur in M. sexta vitellogenin. In vitro uptake with isolated M. sexta follicles showed that deglycosylation had no significant effect on uptake of ¹²⁵I-labeled vitellogenin.     

Structural studies of a specific polysaccharide isolated from non-agglutinable Vibrio

The purified, specific polysaccharide from Vibrio cholera type NAG, NV 384, O-antigen, 2A, 2Bhuman, contains glucose (5.14%), galactose (4.21%), mannose (64.8%), xylose (3.16%), arabinose (1.98%), fucose (1.50%), mannuronic acid (14.3%), phosphate (0.32%), 2-amino-2-deoxy-D-glucose (2.9%), and 2-amino-2-deoxy-D-galactose (1.0%). Various reactions have shown that the material comprises a phosphoric diester-linked polysaccharide containing mainly (1→2)-linked mannopyranose residues that are highly branched with other sugar residues.     

Tests Whether a Head to Head Condensation Mechanism Occurs in the Biosynthesis of n-Hentriacontane, the Paraffin of Spinach and Pea Leaves

Isobutyrate-1-¹⁴C and l-isoleucine-U-¹⁴C fed through the petiole labeled the surface lipids of broccoli leaves, but the incorporation was much less than from straight chain precursors. Not more than one-third of the ¹⁴C incorporated into the surface lipids was found in the C₂₉ paraffin and derivatives, whereas more than two-thirds of the ¹⁴C from straight chain precursors are usually found in these compounds. The small amount of ¹⁴C incorporated into the paraffin fraction was found in the n-C₂₉ paraffin rather than branched paraffins showing that the ¹⁴C in the paraffin must have come from degradation products. Radio gas-liquid chromatography of the saturated fatty acids showed that, in addition to the n-C₁₆ acid which was formed from both branched precursors, isoleucine-U-¹⁴C gave rise to branched C₁₅, C₁₇, and C₁₉ fatty acids, and isobutyrate-1-¹⁴C gave rise to branched C₁₆ and C₁₈ acids. Thus the reason for the failure of broccoli leaf to incorporate branched precursors into branched paraffins is not the unavailability of branched fatty acids, but the absolute specificity of the system that synthesizes paraffins, probably the elongation-decar-boxylation enzyme complex. Consistent with this view, no labeled branched fatty acids longer than C₁₉ could be found in the broccoli leaf. The branched fatty acids were also found in the surface lipids indicating that the epidermal layer of cells did have access to branched chains. Thus the paraffin synthesizing enzyme system is specific for straight chains in broccoli, but the fatty acid synthetase is not.     

Isolation and characterization of β-d-glucan,heteropolysaccharide, and trehalose components of the basidiomycetous lichen Cora pavonia

Cora pavonia, a lichen having a basidiomycetous mycobiont, is rich in protein (36%), of which 10% is tyrosine. α,α-Trehalose is present and was isolated in 4.4% yield. The lichen was found to contain polysaccharides typical of basidiomycetes and different from those of ascomycetes and ascomycetous lichens. Isolated and characterized were a β-d-glucan and a heteropolysaccharide containing l-rhamnose, l-fucose, d-xylose, d-mannose, d-glucose, and d-galactose. The β-d-glucan was highly branched with 21% of nonreducing end-groups, contained 3-O-, 6-O-, and 3,6-di-O-substituted β-d-glucopyranosyl units, and had a main chain consisting of (1→3)- and (1→6)-links. The heteropolysaccharide component contained mainly mannose and xylose, having a mannose-containing nucleus and a main chain with preponderant (1→3)-linked α-d-mannopyranosyl residues. These were unsubstituted (10%), and 4-O- (10%) and 2,4-di-O-substituted (10%) with residues of β-d-xylopyranose. On methylation analysis of the heteropolysaccharide, a capillary column of DB-210 proved to be particularly useful for gas-liquid chromatographic resolution of partially O-methylated alditol acetates.